Its rover initiated a subroutine powered by a computer vision algorithm, effortlessly tracking the pattern and hitting the correct TV without human help.
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At line 23 I define the vcl_recv subroutine and lines 10 – 16 has the logic I need to remove the cache busting parameter.
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My own role in it was like a user-exit subroutine, an odd branch where anything might happen but from which we must return, tracing back to the mainline procedure.
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They shut their eyes, imagining if their Bigurl felt the same, if it was a feel that was the thing, not just a subroutine, damaged, with an extra waypoint added out of Joe's personal allotment.
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For example, there's a subroutine that smooths the movement of the stick figures so the dancers don't jerk about too much, and there's a completely separate neural network dedicated to retracing the target's face to ensure realism.
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Example() ' Calls the subroutine Sub Example ' Begins the subroutine TextWindow.WriteLine("This is an example of a subroutine in Microsoft Small Basic.") ' What the subroutine does EndSub ' Ends the subroutine In the example above, `Example()` calls the subroutine. To define the actual subroutine, the `Sub` keyword must be used, with the subroutine name following `Sub`.
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Subroutines are defined with the `sub` keyword and are invoked simply by naming them. If the subroutine in question has not yet been declared, invocation requires either parentheses after the function name or an ampersand (&) before it. But using & without parentheses will also implicitly pass the arguments of the current subroutine to the one called, and using & with parentheses will bypass prototypes. # Calling a subroutine # Parentheses are required here if the subroutine is defined later in the code foo(); &foo; # (this also works, but has other consequences regarding arguments passed to the subroutine) # Defining a subroutine sub foo { … } foo; # Here parentheses are not required A list of arguments may be provided after the subroutine name.
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The local register stack provides each subroutine with its own rL local registers, designated by $0 through . Whenever a subroutine is called, a number of local registers are pushed down the stack (by shifting the start of the window). The arguments of the called subroutine are left in the remaining local registers. When a subroutine finishes it pops the previously pushed registers.
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The array may contain subroutine pointers (or relative subroutine numbers that can be acted upon by SWITCH statements) that direct the path of the execution.
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Arguments to the `DS` statement are the subroutine number and a subroutine scaling factor. There are no arguments to the `DF` statement. The scaling factor for a subroutine consists of a numerator followed by a denominator that will be applied to all values inside the subroutine. This scaling allows large numbers to be expressed with fewer digits and allows ease of rescaling a design.
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Semantically many statements differ from subroutine calls by their handling of parameters. Usually an actual subroutine parameter is evaluated once before the subroutine is called. This contrasts to many statement parameters that can be evaluated several times (e.g. the condition of a while loop) or not at all (e.g.
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A test suite for a primality testing subroutine might consist of a list of numbers and their primality (prime or composite), along with a testing subroutine. The testing subroutine would supply each number in the list to the primality tester, and verify that the result of each test is correct.
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A simple implementation of "call by name" might substitute the code of an argument expression for each appearance of the corresponding parameter in the subroutine, but this can produce multiple versions of the subroutine and multiple copies of the expression code. As an improvement, the compiler can generate a helper subroutine, called a thunk, that calculates the value of the argument. The address and environment of this helper subroutine are then passed to the original subroutine in place of the original argument, where it can be called as many times as needed. Peter Ingerman first described thunks in reference to the ALGOL 60 programming language, which supported call-by-name evaluation.
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In computer programming, a parameter or a formal argument, is a special kind of variable, used in a subroutine to refer to one of the pieces of data provided as input to the subroutine. These pieces of data are the values of the arguments (often called actual arguments or actual parameters) with which the subroutine is going to be called/invoked. An ordered list of parameters is usually included in the definition of a subroutine, so that, each time the subroutine is called, its arguments for that call are evaluated, and the resulting values can be assigned to the corresponding parameters. Unlike argument in usual mathematical usage, the argument in computer science is thus the actual input expression passed/supplied to a function, procedure, or routine in the invocation/call statement, whereas the parameter is the variable inside the implementation of the subroutine.
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An indirect jump could then be made based on the value of that register, efficiently dispatching program control to the code appropriate to the input. In a similar manner, subroutine call instructions can be indirect, with the address of the subroutine to be called specified in memory. Function Pointers are typically implemented with indirect subroutine calls. Indirect branches were one of the attack surfaces of Spectre.
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In computer programming, a thunk is a subroutine used to inject an additional calculation into another subroutine. Thunks are primarily used to delay a calculation until its result is needed, or to insert operations at the beginning or end of the other subroutine. They have many other applications in compiler code generation and modular programming. The term originated as a humorous, incorrect, past participle of "think".
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A subroutine call not only branches but saves the preceding contents of the PC somewhere. A return retrieves the saved contents of the PC and places it back in the PC, resuming sequential execution with the instruction following the subroutine call.
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Subroutine libraries in Perl are called modules, and modules that contain xsubs are called XS modules. Perl provides a framework for developing, packaging, distributing, and installing modules. It may be desirable for a Perl program to invoke a C subroutine in order to handle very CPU or memory intensive tasks, to interface with hardware or low- level system facilities, or to make use of existing C subroutine libraries.
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Each subroutine could then be provided by a separate piece of tape, loaded or spliced before or after the main program (or "mainline" ); and the same subroutine tape could then be used by many different programs. A similar approach applied in computers that used punched cards for their main input. The name subroutine library originally meant a library, in the literal sense, which kept indexed collections of tapes or card-decks for collective use.
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In computer science, a tail call is a subroutine call performed as the final action of a procedure. If the target of a tail is the same subroutine, the subroutine is said to be tail-recursive, which is a special case of direct recursion. Tail recursion (or tail-end recursion) is particularly useful, and often easy to handle in implementations. Tail calls can be implemented without adding a new stack frame to the call stack.
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The command (abbreviation D) branches execution to a subroutine. It is the equivalent of BASIC's . The subroutine is referenced either by group number or line number. If a line number is provided, that single line is run and then returns to the statement after the .
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For normal application work all peripheral commands, except perhaps RW, would be placed in a subroutine.
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Another advance was the jump to subroutine instruction, which combined the saving of the return address with the calling jump, thereby minimizing overhead significantly. In the IBM System/360, for example, the branch instructions BAL or BALR, designed for procedure calling, would save the return address in a processor register specified in the instruction, by convention register 14. To return, the subroutine had only to execute an indirect branch instruction (BR) through that register. If the subroutine needed that register for some other purpose (such as calling another subroutine), it would save the register's contents to a private memory location or a register stack.
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In the definition of NP-complete given above, the term reduction was used in the technical meaning of a polynomial-time many-one reduction. Another type of reduction is polynomial-time Turing reduction. A problem \scriptstyle X is polynomial-time Turing-reducible to a problem \scriptstyle Y if, given a subroutine that solves \scriptstyle Y in polynomial time, one could write a program that calls this subroutine and solves \scriptstyle X in polynomial time. This contrasts with many-one reducibility, which has the restriction that the program can only call the subroutine once, and the return value of the subroutine must be the return value of the program.
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A call stack is used for several related purposes, but the main reason for having one is to keep track of the point to which each active subroutine should return control when it finishes executing. An active subroutine is one that has been called, but is yet to complete execution, after which control should be handed back to the point of call. Such activations of subroutines may be nested to any level (recursive as a special case), hence the stack structure. For example, if a subroutine `DrawSquare` calls a subroutine `DrawLine` from four different places, `DrawLine` must know where to return when its execution completes.
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In computer programming, a semipredicate problem occurs when a subroutine intended to return a useful value can fail, but the signalling of failure uses an otherwise valid return value. The problem is that the caller of the subroutine cannot tell what the result means in this case.
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The scale factor cannot be changed for each invocation of the subroutine since it is applied to the definition. As an example, the subroutine of Fig. B.4 can be described formally as follows: DS 10 20 2; B10 20 5 5; W1 5 5 10 15; DF; Note that the scale factor is 20/2, which allows the trailing zero to be dropped from all values inside the subroutine. Arbitrary depth of hierarchy is allowed in CIF subroutines.
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The early years of compiler research saw broad experimentation with different evaluation strategies. A key question was how to compile a subroutine call if the arguments can be arbitrary mathematical expressions rather than constants. One approach, known as "call by value", calculates all of the arguments before the call and then passes the resulting values to the subroutine. In the rival "call by name" approach, the subroutine receives the unevaluated argument expression and must evaluate it.
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Arguments may be scalars, lists, or hashes. foo $x, @y, %z; The parameters to a subroutine do not need to be declared as to either number or type; in fact, they may vary from call to call. Any validation of parameters must be performed explicitly inside the subroutine. Arrays are expanded to their elements; hashes are expanded to a list of key/value pairs; and the whole lot is passed into the subroutine as one flat list of scalars.
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In the compiling method called threaded code, the executable program is basically a sequence of subroutine calls.
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The PAM has been used as a subroutine in a truthful cardinal mechanism for one-sided matching.
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In programming, a tag is an argument to a subroutine that determines other arguments passed to it, which is used as a way to pass indefinite number of tagged parameters to the subroutine; notably, tags are used for a number of system calls in AmigaOS v2.0 and onwards.
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Compared to using in-line code, invoking a subroutine imposes some computational overhead in the call mechanism. A subroutine typically requires standard housekeeping code – both at the entry to, and exit from, the function (function prologue and epilogue – usually saving general purpose registers and return address as a minimum).
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A computer program or subroutine that stems word may be called a stemming program, stemming algorithm, or stemmer.
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A polynomial-time Turing reduction from a problem A to a problem B is an algorithm that solves problem A using a polynomial number of calls to a subroutine for problem B, and polynomial time outside of those subroutine calls. Polynomial-time Turing reductions are also known as Cook reductions, named after Stephen Cook. A reduction of this type may be denoted by the expression A \le_T^P B. Many-one reductions can be regarded as restricted variants of Turing reductions where the number of calls made to the subroutine for problem B is exactly one and the value returned by the reduction is the same value as the one returned by the subroutine.
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With the advent of numerical programming, sophisticated subroutine libraries became useful. These libraries would contain subroutines for common high-level mathematical operations such as root finding, matrix inversion, and solving systems of equations. The language of choice was FORTRAN. The most prominent numerical programming library was IBM's Scientific Subroutine Package (SSP).
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Another part of a calling convention is which registers are guaranteed to retain their values after a subroutine call.
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XS is a Perl foreign function interface through which a program can call a C or C++ subroutine. XS or xsub is an abbreviation of "eXternal Subroutine", where external refers to programming languages external to Perl. XS also refers to a glue language for specifying calling interfaces supporting such interfaces (see below).
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This can present a security bug if an attack can cause resource exhaustion. Resource leaks may happen under regular program flow – such as simply forgetting to release a resource – or only in exceptional circumstances, such as when a resource is not released if there is an exception in another part of the program. Resource leaks are very frequently caused by early exit from a subroutine, either by a `return` statement, or an exception raised either by the subroutine itself, or a deeper subroutine that it calls. While resource release due to return statements can be handled by carefully releasing within the subroutine before the return, exceptions cannot be handled without some additional language facility that guarantees that release code is executed.
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Thus, each bit exists in only one place in memory (see "Don't repeat yourself"). The top-level application in these programs may consist of nothing but subroutine calls. Many of these subroutines, in turn, also consist of nothing but lower-level subroutine calls. This technique code refactoring remains widely used today, although for different reasons.
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The Nuts and Volts of BASIC Stamps (Volume 1), July 1996. For example, a GOSUB statement uses 20 bits, including 11 bit-oriented addressing bits for the subroutine address. Because statements are non-byte-aligned, a subroutine can start on any bit in any byte in the EEPROM.Chuck McManis, "Decoding the BASIC Stamp" , 1994.
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At run time, a tiny "interpreter" would scan over the top-level code, extract the subroutine's address in memory, and call it. In other systems, this same basic concept is implemented as a branch table, dispatch table, or virtual method table, all of which consist of a table of subroutine addresses. During the 1970s, hardware designers spent considerable effort to make subroutine calls faster and simpler. On the improved designs, only a single instruction is expended to call a subroutine, so the use of a pseudo-instruction saves no room.
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The `CALL` statement (or the letter `C`) invokes a collection of other statements that have been packaged with `DS` and `DF`. All subroutines are given numbers when they are defined and these numbers are used in the `CALL` to identify them. If, for example, a `LAYER` statement and a `BOX` statement are packaged into subroutine 4, then the statement: C 4; will cause the box to be drawn on that layer. In addition to simply invoking the subroutine, a `CALL` statement can include transformations to affect the geometry inside the subroutine.
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Usually the call stack manipulation needed at the site of a call to a subroutine is minimal (which is good since there can be many call sites for each subroutine to be called). The values for the actual arguments are evaluated at the call site, since they are specific to the particular call, and either pushed onto the stack or placed into registers, as determined by the used calling convention. The actual call instruction, such as "branch and link", is then typically executed to transfer control to the code of the target subroutine.
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Such a choice can only work if no two removed vertices are adjacent, and for each such choice, the subroutine must include in the cover all the vertices outside that are incident to an edge that becomes uncovered by this removal. Using this subroutine in an iterative compression algorithm gives a simple algorithm for vertex cover.
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These parsers can run several times faster than the generic parser loop in table-driven parsers. The fastest parsers use generated assembler code. In the recursive ascent parser variation, the explicit parse stack structure is also replaced by the implicit stack used by subroutine calls. Reductions terminate several levels of subroutine calls, which is clumsy in most languages.
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Another bit was required for sign. This, logically, was rounded up to 12 bits which also resulted in an address space of 16 kilo-words. There was no "stack" for subroutine calls and returns. Rather the Instruction Pointer Register was "swapped" with another register that had been previously filled with the address of the target subroutine.
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Subroutines and Functions are executed at a new scoping level, which is removed when they finish. The communication with the calling scoping level is carried out through the argument list (in both directions). This implements data hiding, i.e. objects created within a Subroutine or a Function are not visible to other Subroutine and Functions but through argument lists.
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Forward references are allowed provided that a subroutine is defined before it is used. Thus the sequence: DS 10; ... C 11; DF; DS 11; ... DF; C 10; is legal, but the sequence: C 11; DS 11; ... DF; is not. This is because the actual invocation of subroutine 11 does not occur until after its definition in the first example.
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A wrapper function is a subroutine (another word for a function) in a software library or a computer program whose main purpose is to call a second subroutine or a system call with little or no additional computation. Wrapper functions are used to make writing computer programs easier by abstracting away the details of a subroutine's underlying implementation.
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In GPUs, the thread scheduling usually cannot be hidden from the application software, and is often controlled with a specialized subroutine library.
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Under this approach, the size of the area is calculated by the compiler to be the largest needed by any called subroutine.
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The processor does not have standard subroutine CALL address and RET instructions, though they can be simulated. The 16-register design makes possible some interesting subroutine call and return mechanisms, though they are better suited to small programs than general purpose coding. A few commonly used subroutines can be called quickly by keeping their address in one of the 16 registers; however, the called subroutine must know (hard coded) what the calling PC register is to perform the "return" instruction. The SEP instruction is used to call a subroutine pointed to by one of the 16-bit registers and another SEP to return to the caller (SEP stands for Set Program Counter, and selects which one of the 16 registers is to be used as the program counter from that point onward).
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In the called subroutine, the first code executed is usually termed the subroutine prologue, since it does the necessary housekeeping before the code for the statements of the routine is begun. For instruction set architectures in which the instruction used to call a subroutine puts the return address into a register, rather than pushing it onto the stack, the prologue will commonly save the return address by pushing the value onto the call stack, although if the called subroutine does not call any other routines it may leave the value in the register. Similarly, the current stack pointer and/or frame pointer values may be pushed. If frame pointers are being used, the prologue will typically set the new value of the frame pointer register from the stack pointer.
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Cobol, Fortran, and RPG generated object code (type O). Basic was interpreted only; a compilation utility called BASICS created subroutine code (type R). Basic programs could be saved as sources for compatibility with other computers, but the project's text was preserved in the subroutine (unless the programmer used the LOCK parameter to keep it private.) Procedures, which use OCL to start programs and assign resources to them, are type P. Source members for all objects are type S, with the exception of Basic as above-specified. DFU programs generated subroutine (R) code. So did WSU programs. Screen formats generated object code.
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The geometry statements are: `LAYER` to switch mask layers, `BOX` to draw a rectangle, `WIRE` to draw a path, `ROUNDFLASH` to draw a circle, `POLYGON` to draw an arbitrary figure, and `CALL` to draw a subroutine of other geometry statements. The control statements are `DS` to start the definition of a subroutine, `DF` to finish the definition of a subroutine, `DD` to delete the definition of subroutines, `0` through `9` to include additional user-specified information, and `END` to terminate a CIF file. All of these keywords are usually abbreviated to one or two letters that are unique.
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The libraries would include single-precision and double-precision versions of some algorithms. Initially, these subroutines used hard-coded loops for their low-level operations. For example, if a subroutine need to perform a matrix multiplication, then the subroutine would have three nested loops. Linear algebra programs have many common low-level operations (the so-called "kernel" operations, not related to operating systems).
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The ACE implemented subroutine calls, whereas the EDVAC did not, and the ACE also used Abbreviated Computer Instructions, an early form of programming language.
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It has been used as a subroutine in other graph algorithms including the recognition of chordal graphs, and optimal coloring of distance-hereditary graphs.
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Sixteen registers (registers 48 to 63) were referred to as "global registers" and they correspond to the registers of a typical CPU, in that they are static and always visible. The other 48 registers were actually the top of the subroutine stack. Thirty-two of them (0–31) were local registers for the current subroutine, and registers 32–47 were used to pass up to 16 parameters to the next subroutine called. During a subroutine call, the register stack moved up 32 words, so the caller's registers 32–47 became the called subroutine's registers 0–15. The return instruction dropped the stack by 32 words so return parameters would be visible to the caller in registers 32–47. The stack cache held 16 levels in the CPU and stack overflow and underflow was automatically handled by the microcode of the CPU.
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A wide number of conventions for the coding of subroutines have been developed. Pertaining to their naming, many developers have adopted the approach that the name of a subroutine should be a verb when it does a certain task, and adjective when it makes some inquiry, and a noun when it is used to substitute variables. Some programmers suggest that a subroutine should perform only one task, and if a subroutine does perform more than one task, it should be split up into more subroutines. They argue that subroutines are key components in code maintenance, and their roles in the program must remain distinct.
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This simple control table directs program flow according to the value of the single input variable. Each table entry holds a possible input value to be tested for equality (implied) and a relevant subroutine to perform in the action column. The name of the subroutine could be replaced by a relative subroutine number if pointers are not supported Control tables are tables that control the control flow or play a major part in program control. There are no rigid rules about the structure or content of a control table--its qualifying attribute is its ability to direct control flow in some way through "execution" by a processor or interpreter.
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COBOL, FORTRAN, and RPG generated object code (type O). BASIC was interpreted only; a compilation utility called BASICS created subroutine code (type R). BASIC programs could be saved as sources for compatibility with other computers, but the project's text was preserved in the subroutine (unless the programmer used the LOCK command to keep it private.) Procedures, which use OCL to start programs and assign resources to them, are type P. Source members for all objects are type S, with the exception of BASIC as specified above. DFU programs generated subroutine (R) code, as did WSU programs. Screen formats generated object code. Menus generated object code.
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To avoid the performance issues that plagued the i432, the central i960 instruction-set architecture was a RISC design, which was only implemented in full in the i960MX. The memory subsystem was 33-bits wide—to accommodate a 32-bit word and a "tag" bit to implement memory protection in hardware. In many ways, the i960 followed the original Berkeley RISC design, notably in its use of register windows, an implementation-specific number of caches for the per-subroutine registers that allowed for fast subroutine calls. The competing Stanford University design, MIPS, did not use this system, instead relying on the compiler to generate optimal subroutine call and return code.
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Special Array Value is padlist which is an array of array. Its 0th element to an AV containing all lexical variable names (with prefix symbols) used within that subroutine. The padlist's first element points to a scratchpad AV, whose elements contain the values corresponding to the lexical variables named in the 0th row. Another elements of padlist are created when the subroutine recurses or new thread is created.
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In computer programming, a subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. Subroutines may be defined within programs, or separately in libraries that can be used by many programs. In different programming languages, a subroutine may be called a routine, subprogram, function, method, or procedure.
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The idea of a subroutine was initially conceived by John Mauchly during his work on ENIAC, and recorded in a January 1947 Harvard symposium on "Preparation of Problems for EDVAC-type Machines".J.W. Mauchly, "Preparation of Problems for EDVAC-type Machines" (1947), in Brian Randell (Ed.), The Origins of Digital Computers, Springer, 1982. Maurice Wilkes, David Wheeler, and Stanley Gill are generally credited with the formal invention of this concept, which they termed a closed subroutine, contrasted with an open subroutine or macro. However, Turing had discussed subroutines in a paper of 1945 on design proposals for the NPL ACE, going so far as to invent the concept of a return address stack.
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Since the call stack is organized as a stack, the caller pushes the return address onto the stack, and the called subroutine, when it finishes, pulls or pops the return address off the call stack and transfers control to that address. If a called subroutine calls on yet another subroutine, it will push another return address onto the call stack, and so on, with the information stacking up and unstacking as the program dictates. If the pushing consumes all of the space allocated for the call stack, an error called a stack overflow occurs, generally causing the program to crash. Adding a subroutine's entry to the call stack is sometimes called "winding"; conversely, removing entries is "unwinding".
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In the very early assemblers, subroutine support was limited. Subroutines were not explicitly separated from each other or from the main program, and indeed the source code of a subroutine could be interspersed with that of other subprograms. Some assemblers would offer predefined macros to generate the call and return sequences. By the 1960s, assemblers usually had much more sophisticated support for both inline and separately assembled subroutines that could be linked together.
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Three transformations can be applied to a subroutine in CIF: translation, rotation, and mirroring. Translation is specified as the letter `T` followed by an x, y offset. These offsets will be added to all coordinates in the subroutine, to translate its graphics across the mask. Rotation is specified as the letter `R` followed by an x, y vector endpoint that, much like the rotation clause in the `BOX` statement, defines a line to the origin.
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The subroutine concept led to the availability of a substantial subroutine library. By 1951, 87 subroutines in the following categories were available for general use: floating point arithmetic; arithmetic operations on complex numbers; checking; division; exponentiation; routines relating to functions; differential equations; special functions; power series; logarithms; miscellaneous; print and layout; quadrature; read (input); nth root; trigonometric functions; counting operations (simulating repeat until loops, while loops and for loops); vectors; and matrices.
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In the mathematical subfield of numerical analysis de Boor's algorithmC. de Boor [1971], "Subroutine package for calculating with B-splines", Techn.Rep. LA-4728-MS, Los Alamos Sci.Lab, Los Alamos NM; p.
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In computational complexity theory, a polynomial-time reduction is a method for solving one problem using another. One shows that if a hypothetical subroutine solving the second problem exists, then the first problem can be solved by transforming or reducing it to inputs for the second problem and calling the subroutine one or more times. If both the time required to transform the first problem to the second, and the number of times the subroutine is called is polynomial, then the first problem is polynomial-time reducible to the second. A polynomial-time reduction proves that the first problem is no more difficult than the second one, because whenever an efficient algorithm exists for the second problem, one exists for the first problem as well.
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It is important to keep track of any access or side effects that are done inside a routine designed to be reentrant. Reentrancy of a subroutine that operates on operating-system resources or non-local data depends on the atomicity of the respective operations. For example, if the subroutine modifies a 64-bit global variable on a 32-bit machine, the operation may be split into two 32-bit operations, and thus, if the subroutine is interrupted while executing, and called again from the interrupt handler, the global variable may be in a state where only 32 bits have been updated. The programming language might provide atomicity guarantees for interruption caused by an internal action such as a jump or call.
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As nested calls accumulate, a call stack structure is formed, consisting of one activation record for each suspended subprogram. In fact, this stack structure is virtually ubiquitous, and so activation records are commonly termed stack frames. Some languages such as Pascal, PL/I, and Ada also support nested subroutines, which are subroutines callable only within the scope of an outer (parent) subroutine. Inner subroutines have access to the local variables of the outer subroutine that called them.
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Proponents of modular programming (modularizing code) advocate that each subroutine should have minimal dependency on other pieces of code. For example, the use of global variables is generally deemed unwise by advocates for this perspective, because it adds tight coupling between the subroutine and these global variables. If such coupling is not necessary, their advice is to refactor subroutines to accept passed parameters instead. However, increasing the number of parameters passed to subroutines can affect code readability.
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In computer programming, a return statement causes execution to leave the current subroutine and resume at the point in the code immediately after the instruction which called the subroutine, known as its return address. The return address is saved by the calling routine, today usually on the process's call stack or in a register. Return statements in many languages allow a function to specify a return value to be passed back to the code that called the function.
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Mainframes and some early microprocessors such as the RCA 1802 required several instructions to call a subroutine. In the top-level application and in many subroutines, that sequence is constantly repeated, with only the subroutine address changing from one call to the next. This means that a program consisting of many function calls may have considerable amounts of repeated code as well. To address this, threaded code systems used pseudo-code to represent function calls in a single operator.
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For example, as noted below, inadvertent recursion of a subroutine produces defects that are difficult to trace to the subroutine in question. As design advances reduced the costs of logic and memory, the programmer's time became relatively more important. Subsequent computer designs emphasized ease of programming, typically using larger and more intuitive instruction sets.a phrase used in Section 1.1 of "Introduction to the Central Processing Unit (CPU)" of a 2007 document about a Texas Instruments microcomputer.
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Ada 83 supports slices for all array types. Like Fortran 77 such arrays could be passed by _reference_ to another subroutine, the length would also be passed transparently to the subroutine as a kind of short dope vector. with Text_IO; procedure Main is Text : String := "ABCDE"; begin Text_IO.Put_Line (Text (2 .. 4)); end Main; Produces: BCD Note: Since in Ada indices are n-based the term `Text (2 .. 4)` will result in an Array with the base index of 2.
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Sub Main() This line defines a subroutine called "Main". "Main" is the entry point, where the program begins execution. Console.WriteLine("Hello, world!") This line performs the actual task of writing the output.
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Many versions of Fortran include a `CALL LINK` statement that performs chain loading, preserving the contents of COMMON storage. This is not the same as the unrelated `LINK` subroutine in GNU Fortran.
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In contrast, call by reference and call by name semantics allow the parameters to act as aliases of the values passed as arguments, allowing the subroutine to modify variables outside its own scope.
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This use is still relevant in certain ultra-RISC architectures, at least theoretically; see for example one instruction set computer. Donald Knuth's MIX architecture also used self-modifying code to implement subroutine calls.
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Nevertheless, Lawler shows that S may be found in polynomial time by a binary search algorithm in which each step of the search uses an instance of the closure problem as a subroutine.
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According to the Intel ABI to which the vast majority of compilers conform, the EAX, EDX, and ECX are to be free for use within a procedure or function, and need not be preserved. As the name implies, these general-purpose registers usually hold temporary (volatile) information, that can be overwritten by any subroutine. Therefore, it is the caller's responsibility to push each of these registers onto the stack, if it would like to restore their values after a subroutine call.
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Wheeler's contributions to the field included work on the Electronic delay storage automatic calculator (EDSAC) in the 1950s and the Burrows–Wheeler transform (published 1994). Along with Maurice Wilkes and Stanley Gill, he is credited with the invention around 1951 of the subroutine (which they referred to as the closed subroutine), and gave the first explanation of how to design software libraries; as a result, the jump to subroutine instruction was often called a Wheeler Jump. Wilkes published a paper in 1953 discussing relative addressing to facilitate the use of subroutines.Proceedings of the Cambridge Philosophical Society, Vol 49, Pt 1, pgs 84-9 (However, Turing had discussed subroutines in a paper of 1945 on design proposals for the NPL ACE, going so far as to invent the concept of a return address stack.
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For example, if one defines the `add` subroutine as `def add(x, y): return x + y`, then `x, y` are parameters, while if this is called as `add(2, 3)`, then `2, 3` are the arguments. Note that variables (and expressions thereof) from the calling context can be arguments: if the subroutine is called as `a = 2; b = 3; add(a, b)` then the variables `a, b` are the arguments, not the values `2, 3`. See the Parameters and arguments section for more information. In the most common case, call by value, a parameter acts within the subroutine as a new local variable initialized to the value of the argument (a local (isolated) copy of the argument if the argument is a variable), but in other cases, e.g.
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In computing, a computer program or subroutine is called reentrant if multiple invocations can safely run concurrently on a single processor system, where a reentrant procedure can be interrupted in the middle of its execution and then safely be called again ("re-entered") before its previous invocations complete execution. The interruption could be caused by an internal action such as a jump or call, or by an external action such as an interrupt or signal, unlike recursion, where new invocations can only be caused by internal call. This definition originates from multiprogramming environments where the flow of control could be interrupted by an interrupt and transferred to an interrupt service routine (ISR) or "handler" subroutine. Any subroutine used by the handler that could potentially have been executing when the interrupt was triggered should be reentrant.
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In addition to the simple jump operations, there are the `call` (call a subroutine) and `ret` (return from subroutine) instructions. Before transferring control to the subroutine, `call` pushes the segment offset address of the instruction following the `call` onto the stack; `ret` pops this value off the stack, and jumps to it, effectively returning the flow of control to that part of the program. In the case of a `far call`, the segment base is pushed following the offset; `far ret` pops the offset and then the segment base to return. There are also two similar instructions, `int` (interrupt), which saves the current (E)FLAGS register value on the stack, then performs a `far call`, except that instead of an address, it uses an interrupt vector, an index into a table of interrupt handler addresses.
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Some languages use a special keyword (e.g. void) to indicate that the subroutine has no parameters; in formal type theory, such functions take an empty parameter list (whose type is not void, but rather unit).
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In most Forth systems, the body of a code definition consists of either machine language, or some form of threaded code. The original Forth which follows the informal FIG standard (Forth Interest Group), is a TIL (Threaded Interpretive Language). This is also called indirect-threaded code, but direct-threaded and subroutine threaded Forths have also become popular in modern times. The fastest modern Forths use subroutine threading, insert simple words as macros, and perform peephole optimization or other optimizing strategies to make the code smaller and faster.
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A method used to eliminate this overhead is inline expansion or inlining of the subprogram's body at each call site (versus branching to the subroutine and back). Not only does this avoid the call overhead, but it also allows the compiler to optimize the procedure's body more effectively by taking into account the context and arguments at that call. The inserted body can be optimized by the compiler. Inlining, however, will usually increase the code size, unless the program contains only one call to the subroutine.
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SUBROUTINE TO READ RECORD INTO BUFFER . RDREC LDX ZERO LDA ZERO RLOOP TD INPUT JEQ RLOOP RD INPUT COMP ZERO JEQ EXIT STCH BUFFER,X TIX MAXLEN JLT RLOOP EXIT STX LENGTH RSUB INPUT BYTE X'F1' MAXLEN WORD 4096 . . SUBROUTINE TO WRITE RECORD FROM BUFFER . WRREC LDX ZERO WLOOP TD OUTPUT JEQ WLOOP LDCH BUFFER,X WD OUTPUT TIX LENGTH JLT WLOOP RSUB OUTPUT BYTE X'06' END FIRST ` If you were to assemble this program, you would get the object code depicted below.
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As noted above, the primary purpose of a call stack is to store the return addresses. When a subroutine is called, the location (address) of the instruction at which the calling routine can later resume needs to be saved somewhere. Using a stack to save the return address has important advantages over alternative calling conventions. One is that each task can have its own stack, and thus the subroutine can be thread- safe, that is, can be active simultaneously for different tasks doing different things.
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Conditional branches are based on the arithmetic sign (negative, zero, or positive) of the last piece of data written into the register file. Unconditional branches may move execution to a location given by a register value or a PC-relative offset. Three instructions (JSR, JSRR, and TRAP) support the notion of subroutine calls by storing the address of the code calling the subroutine into a register before changing the value of the program counter. The LC-3 does not support the direct arithmetic comparison of two values.
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Subtraction and bitwise logical operations on 16 bits is done in 8-bit steps. Operations that have to be implemented by program code (subroutine libraries) include comparisons of signed integers as well as multiplication and division.
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The MySQL database supports stored procedures. A stored procedure is a subroutine stored in the database catalog. Applications can call and execute the stored procedure. The CALL SQL statement is used to execute a stored procedure.
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In systems such as the HP 2100, the JSB instruction would perform a similar task, except that the return address was stored in the memory location that was the target of the branch. Execution of the procedure would actually begin at the next memory location. In the HP 2100 assembly language, one would write, for example ... JSB MYSUB (Calls subroutine MYSUB.) BB ... (Will return here after MYSUB is done.) to call a subroutine called MYSUB from the main program. The subroutine would be coded as MYSUB NOP (Storage for MYSUB's return address.) AA ... (Start of MYSUB's body.) ... JMP MYSUB,I (Returns to the calling program.) The JSB instruction placed the address of the NEXT instruction (namely, BB) into the location specified as its operand (namely, MYSUB), and then branched to the NEXT location after that (namely, AA = MYSUB + 1).
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An example layout of a call stack. The subroutine `DrawLine` has been called by `DrawSquare`. Note that the stack is growing upwards in this diagram. Return-oriented programming is an advanced version of a stack smashing attack.
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Data realises that she is breaking up with him and explains that he will delete the subroutine. D'Sora departs and Data is seemingly unperturbed, although his cat, Spot, jumps into his lap as if to comfort him.
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Technically, these terms all have different definitions. The generic, umbrella term callable unit is sometimes used. The name subprogram suggests a subroutine behaves in much the same way as a computer program that is used as one step in a larger program or another subprogram. A subroutine is often coded so that it can be started several times and from several places during one execution of the program, including from other subroutines, and then branch back (return) to the next instruction after the call, once the subroutine's task is done.
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The subroutine could then return to the main program by executing the indirect jump JMP MYSUB, I which branched to the location stored at location MYSUB. Compilers for Fortran and other languages could easily make use of these instructions when available. This approach supported multiple levels of calls; however, since the return address, parameters, and return values of a subroutine were assigned fixed memory locations, it did not allow for recursive calls. Incidentally, a similar method was used by Lotus 1-2-3, in the early 1980s, to discover the recalculation dependencies in a spreadsheet.
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This difference may in some rare cases lead to unresolved externals when porting such code to 64 bits. For example, Fortran code can use 'alias' to link against a C method by name as follows: SUBROUTINE f() !DEC$ ATTRIBUTES C, ALIAS:'_f' :: f END SUBROUTINE This will compile and link fine under 32 bits, but generate an unresolved external `_f` under 64 bits. One workaround for this is not to use 'alias' at all (in which the method names typically need to be capitalized in C and Fortran).
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The primary use of these was to use a group as a subroutine which can be called with , for instance, which will jump to the subroutine written in group 5. The editor also used these during edit-time, for instance, one could to produce a listing of the code in group 2, or to delete all of the lines in group 4. Every line must start with a command keyword following the line number. There is no concept of a "default command" as is the case in BASIC with its optional statement.
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This means that when a recursive function calls itself, local variables in each instance of the function are given distinct addresses. Hence variables of this scope can be declared, written to, and read, without any risk of side-effects to functions outside of the block in which they are declared. Programming languages that employ call by value semantics provide a called subroutine with its own local copy of the arguments passed to it. In most languages, these local parameters are treated the same as other local variables within the subroutine.
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Machine level branch instructions are sometimes called jump instructions. Machine level jump instructions typically have unconditional and conditional forms where the latter may be taken or not taken depending on some condition. Usually there are distinct forms for one-way jumps, often called jump and subroutine invocations known as call which automatically save the originating address as a return address on the stack, allowing a single subroutine to be invoked from multiple locations in code. In CPUs with flag registers, an earlier instruction sets a condition in the flag register.
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RISC-V also recycles to return from a subroutine: To do this, 's base register is set to be the linkage register saved by or . 's offset is zero and the linkage register is zero, so that there is no offset, and no return address is saved. Like many RISC designs, in a subroutine call, a RISC-V compiler must use individual instructions to save registers to the stack at the start, and then restore these from the stack on exit. RISC-V has no save multiple or restore multiple register instructions.
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HSL, originally the Harwell Subroutine Library, is a collection of Fortran 77 and 95 codes that address core problems in numerical analysis. It is primarily developed by the Numerical Analysis Group at the Rutherford Appleton Laboratory with contributions from other experts in the field. HSL codes are easily recognizable by the format of their names, consisting of two letters followed by two numbers, dating back to early versions of Fortran's limited subroutine name length. The letters denote a broad classification of the problem they solve, and the numbers serve to distinguish different codes.
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The proof that the halting problem is not solvable is a proof by contradiction. To illustrate the concept of the proof, suppose that there exists a total computable function halts(f) that returns true if the subroutine f halts (when run with no inputs) and returns false otherwise. Now consider the following subroutine: def g(): if halts(g): loop_forever() halts(g) must either return true or false, because halts was assumed to be total. If halts(g) returns true, then g will call loop_forever and never halt, which is a contradiction.
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Given a list of elements with values or records , and target value , the following subroutine uses linear search to find the index of the target in . # Set to 0. # If , the search terminates successfully; return . # Increase by 1.
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For a search function supporting and handling duplicates in a tree, see section Searching with duplicates allowed. In the context of binary search trees, a total preorder is realized most flexibly by means of a three-way comparison subroutine.
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Perl takes some cues from its C heritage for conventions. Locally scoped variables and subroutine names are lowercase with infix underscores. Subroutines and variables meant to be treated as private are prefixed with an underscore. Package variables are title cased.
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In DOS terminology, an errorlevel is an integer exit code returned by an executable program or subroutine. Errorlevels typically range from 0 to 255. In DOS there are only 256 error codes available. Exit statuses are often captured by batch programs.
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Machines before the late 1960s--such as the PDP-8 and HP 2100--did not have compilers which supported recursion. Their subroutine instructions typically would save the current location in the jump address, and then set the program counter to the next address. While this is simpler than maintaining a stack, since there is only one return location per subroutine code section, there cannot be recursion without considerable effort on the part of the programmer. A stack machine has 2 or more stack registers -- one of them keeps track of a call stack, the other(s) keep track of other stack(s).
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Suppose an algorithm is being developed to operate on a set of n elements. Its developers are interested in finding a function T(n) that will express how long the algorithm will take to run (in some arbitrary measurement of time) in terms of the number of elements in the input set. The algorithm works by first calling a subroutine to sort the elements in the set and then perform its own operations. The sort has a known time complexity of O(n2), and after the subroutine runs the algorithm must take an additional 55n3 + 2n + 10 steps before it terminates.
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In mathematics and computer science, a matroid oracle is a subroutine through which an algorithm may access a matroid, an abstract combinatorial structure that can be used to describe the linear dependencies between vectors in a vector space or the spanning trees of a graph, among other applications. The most commonly used oracle of this type is an independence oracle, a subroutine for testing whether a set of matroid elements is independent. Several other types of oracle have also been used; some of them have been shown to be weaker than independence oracles, some stronger, and some equivalent in computational power.; ; .
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Another benefit is that by providing reentrancy, recursion is automatically supported. When a function calls itself recursively, a return address needs to be stored for each activation of the function so that it can later be used to return from the function activation. Stack structures provide this capability automatically. Depending on the language, operating-system, and machine environment, a call stack may serve additional purposes, including for example: ; Local data storage : A subroutine frequently needs memory space for storing the values of local variables, the variables that are known only within the active subroutine and do not retain values after it returns.
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Generally, will not be specified as a table of values, the way it is shown in the figure above. Rather, a cycle detection algorithm may be given access either to the sequence of values , or to a subroutine for calculating . The task is to find and while examining as few values from the sequence or performing as few subroutine calls as possible. Typically, also, the space complexity of an algorithm for the cycle detection problem is of importance: we wish to solve the problem while using an amount of memory significantly smaller than it would take to store the entire sequence.
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9830s were built with a processor similar in architecture to the HP 1000/2100 series minicomputer with 16-bit memory address, and an AX and BX general processor register. They ran at a speed comparable to the first IBM PCs. They could draw a mesh of a 3D SIN(X)/X function with no hidden lines over the course of several minutes, a technological breakthrough for the time. Because programs were designed to run from ROM (read only memory) the call subroutine instruction had to be changed because in the HP211x the return location was written in the first location of the subroutine.
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Subroutines are special cases of coroutines. When subroutines are invoked, execution begins at the start, and once a subroutine exits, it is finished; an instance of a subroutine only returns once, and does not hold state between invocations. By contrast, coroutines can exit by calling other coroutines, which may later return to the point where they were invoked in the original coroutine; from the coroutine's point of view, it is not exiting but calling another coroutine. Thus, a coroutine instance holds state, and varies between invocations; there can be multiple instances of a given coroutine at once.
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The subroutine interfaces available to user programs are also used by most other parts of the system (system mode programs, CLSs, ...) even through components running in system mode do have access to the "system" virtual memory segment(s). Transitions from user mode to system mode and back are managed by a special protected set of subroutine interfaces known as "the gate" (initially developed at Wayne State University). The programming effort for MTS is divided vertically rather than horizontally. This means that one or two individuals are assigned responsibility for a component and then follow it from design through implementation and maintenance.
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STOIC, unlike other FORTH variants, was integrated with the VMS I/O and system services rather than using the FORTH disk I/O. It also supported machine code (both inline and subroutine calls). STOIC supported double precision floating point operations using a stack.
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The quantum phase estimation algorithm is used to determine the eigenphase of an eigenvector of a unitary gate given a quantum state proportional to the eigenvector and access to the gate. The algorithm is frequently used as a subroutine in other algorithms.
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There is a significant runtime overhead in a calling a subroutine, including passing the arguments, branching to the subprogram, and branching back to the caller. The overhead often includes saving and restoring certain processor registers, allocating and reclaiming call frame storage, etc.. In some languages, each subroutine call also implies automatic testing of the subroutine's return code or the handling of exceptions that it may raise. In object-oriented languages, a significant source of overhead is the intensively used dynamic dispatch for method calls. There are some seemingly obvious optimizations of procedure calls that cannot be applied if the procedures may have side effects.
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In other cases a Null value is returned if there is no explicit return statement: in Python, the value `None` is returned when the return statement is omitted, while in JavaScript the value `undefined` is returned. In Windows PowerShell all evaluated expressions which are not captured (e.g., assigned to a variable, cast to void or piped to $null) are returned from the subroutine as elements in an array, or as a single object in the case that only one object has not been captured. In Perl, a return value or values of a subroutine can depend on the context in which it was called.
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The concept of a code cave is often employed by hackers and reverse engineers to execute arbitrary code in a compiled program. It can be a helpful method to make modifications to a compiled program in the example of including additional dialog boxes, variable modifications or even the removal of software key validation checks. Often using a call instruction commonly found on many CPU architectures, the code jumps to the new subroutine and pushes the next address onto the stack. After execution of the subroutine a return instruction can be used to pop the previous location off of the stack into the program counter.
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In the possible future known as 2099, the Phalanx tried to invade the planet Earth a second time. To prevent Earth from being converted by the Transmode Virus, Spider-Man (Miguel O'Hara) forms an uneasy alliance with Dr. Doom, who had encountered the Phalanx in their first attempt to invade Earth in the 20th century. Doom knew that the Phalanx would have a "scout program" so he added his own subroutine to the coding called subroutine Cynthia which would erase the scout program. When Doom jumped to the future he lost track of the scout program and therefore created the Mutant Messiah myth to track the carrier down again.
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PB determines from which 64KB bank the processor will fetch instructions—there is no programmatic means by which PB can be directly changed. Branches and 16-bit jumps or 16-bit subroutine calls are generally limited to the bank in PB (`JMP()` always fetches the target address from bank $00). A 24-bit "long" jump or subroutine call is possible, which overcomes the normal 64 KB program size limit. A further addition to the register set is the 16-bit Direct Page Register (DP), which sets the base address for what was formerly called the zero page, but now referred to as direct page.
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Let L be empty. # For each vertex u of the graph do Visit(u), where Visit(u) is the recursive subroutine: #: If u is unvisited then: #:# Mark u as visited. #:# For each out-neighbour v of u, do Visit(v). #:# Prepend u to L. #: Otherwise do nothing.
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Data could be stored in 110 memory register. The FX-603P series supported 20 labels for programs and subroutines called P0 .. P19 - twice the amount of the predecessor models. Each program or subroutine could have up to 10 local labels called LBL0 .. LBL9 for jumps and branches.
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Printed output on a Teletype Model 33 ASR was controlled by a single pole relay. A subroutine would convert the LINC character codes into ASCII and use timing loops to toggle the relay on and off, generating the correct 8-bit output to control the Teletype printer.
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There is a screen clear function used during the reset cycle, but it is buried as an in-line routine in the reset code and is not available as a callable subroutine. CPU access to video memory causes noticeable glitches (known as "snow") on the screen.
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This implementation is subroutine-threaded, with about 20 words written in assembly language, and the complete system occupying a total of about 8K of RAM. It was cross-developed from a VAX to an RTX2000 Forth system connected to dual-ported RAM accessible to the microcontroller.
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The Homesick are a Dutch post-punk band from Dokkum, in the north of the Netherlands. The band is composed of drummer Erik Woudwijk, bassist Jaap van der Velde and guitarist Elias Elgersma. They have released the albums Youth Hunt (Subroutine, 2017) and The Big Exercise (Sub Pop, 2020).
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A combination of state variables and structured control, notably an overall switch statement, can allow a subroutine to resume execution at an arbitrary point on subsequent calls, and is a structured alternative to goto statements in the absence of coroutines; this is a common idiom in C, for example.
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Zuse implemented the machine with relays, since vacuum tubes were too unreliable at the time. The Z5 used the same principles as the Z4, but was six times faster. It also had punched tape readers, which the Z4 did not have. It had conditional branching and five subroutine loops.
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It is a two-stack machine, each stack 256 words deep, that supports direct execution of Forth. Subroutine calls and returns only take one processor cycle and it also has a very low and consistent interrupt latency of only four processor cycles, which lends it well to realtime applications.
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Later, Hoare learned about ALGOL and its ability to do recursion that enabled him to publish the code in Communications of the Association for Computing Machinery, the premier computer science journal of the time. Quicksort gained widespread adoption, appearing, for example, in Unix as the default library sort subroutine. Hence, it lent its name to the C standard library subroutine and in the reference implementation of Java. Robert Sedgewick's PhD thesis in 1975 is considered a milestone in the study of Quicksort where he resolved many open problems related to the analysis of various pivot selection schemes including Samplesort, adaptive partitioning by Van Emden as well as derivation of expected number of comparisons and swaps.
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Here an algorithm is developed to determine this distance, based on the analytic results for the distance of closest approach of ellipses in 2D, which can be implemented numerically. Details are given in publications.X. Zheng, W. Iglesias, P. Palffy-Muhoray, "Distance of closest approach of two arbitrary hard ellipsoids", electronic Liquid Crystal Communications, 2008 Subroutines are provided in two formats: Fortran90 Fortran90 subroutine for distance of closest approach of ellipsoids and C. C subroutine for distance of closest approach of ellipsoids The algorithm consists of three steps. # Constructing a plane containing the line joining the centers of the two ellipsoids, and finding the equations of the ellipses formed by the intersection of this plane and the ellipsoids.
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The simplest implementation of a function (or subroutine) pointer is as a variable containing the address of the function within executable memory. Older third-generation languages such as PL/I and COBOL, as well as more modern languages such as Pascal and C generally implement function pointers in this manner.
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OMG (2011). OMG Unified Modeling Language (OMG UML), Superstructure, V2.4.1, p. 507. If a caller sends a synchronous message, it must wait until the message is done, such as invoking a subroutine. If a caller sends an asynchronous message, it can continue processing and doesn’t have to wait for a response.
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Special objects such as "PROGRAM", "SUBROUTINE" and "FUNCTION" objects (collectively referred to as procedures) can be defined for operations automation. Another way for running several instructions with a single command is to store them into a use-file and make the processor read them by mean of the USE command.
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Other subroutines can benefit from the use of link register because it can be saved in a batch with other callee-used registers—e.g. an ARM subroutine pushes registers 4-7 along with the link register, LR, by the single instruction `STMDB SP!, {R4-R7, LR}` pipelining all memory writes required.
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A compiler can implement operators and functions with subroutine calls or with inline code. Some built-in operators supported by a language have a direct mapping to a small number of instructions commonly found on central processing units, though others (e.g. '+' used to express string concatenation) may have complicated implementations.
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In programming, a call site of a function or subroutine is the location (line of code) where the function is called (or may be called, through dynamic dispatch). A call site is where zero or more arguments are passed to the function, and zero or more return values are received.
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There may be several versions of the interpreter to enhance the portability of a control table. A subordinate control table pointer may optionally substitute for a subroutine pointer in the 'action' columns if the interpreter supports this construct, representing a conditional 'drop' to a lower logical level, mimicking a conventional structured program structure.
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During some or maybe all of the iterative model-subroutine calls the engine would invoke automatic differentiation of the formulas in the model holarchy with respect to the model's input-unknowns (arguments) defined in the calling template. Additional mechanisms were performed in the semantics to accommodate ubiquitous nesting of these holistic models.
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It introduced the password encryption system used later by Unix. Its programming system also had an early version control system. Wilkes is also credited with the idea of symbolic labels, macros and subroutine libraries. These are fundamental developments that made programming much easier and paved the way for high-level programming languages.
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The abstraction principle is often stated in the context of some mechanism intended to facilitate abstraction. The basic mechanism of control abstraction is a function or subroutine. Data abstractions include various forms of type polymorphism. More elaborate mechanisms that may combine data and control abstractions include: abstract data types, including classes, polytypism etc.
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The library's wrapper functions expose an ordinary function calling convention (a subroutine call on the assembly level) for using the system call, as well as making the system call more modular. Here, the primary function of the wrapper is to place all the arguments to be passed to the system call in the appropriate processor registers (and maybe on the call stack as well), and also setting a unique system call number for the kernel to call. In this way the library, which exists between the OS and the application, increases portability. The call to the library function itself does not cause a switch to kernel mode and is usually a normal subroutine call (using, for example, a "CALL" assembly instruction in some Instruction set architectures (ISAs)).
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This resulted in faster subroutine calls and interrupt response than traditional designs, which would have to do two register loads or saves when calling or returning from a subroutine. Despite having a 32-bit ALU and word-length, processors based on ARM architecture version 1 and 2 had only a 26-bit PC and address bus, and were consequently limited to 64 MiB of addressable memory. This was still a vast amount of memory at the time, but because of this limitation, architectures since have included various steps away from the original 26-bit design. The ARM architecture version 3 introduced a 32-bit PC and separate PSR, as well as a 32-bit address bus, allowing 4 GiB of memory to be addressed.
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This value has to be stored immediately upon jumping to a subroutine. Otherwise it will be impossible to return. The Cosequence Counter and History perform the same functions for any command that had X, at the beginning of its ARGUS location. The MSK register holds the full location of the first mask (see below).
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She appears to be a close companion of the Freelancers as they greet her when they return from their missions. One subroutine becomes Sheila the tank. In Season 10, in the present day, the same abandoned facility from earlier had become Director's hideout. There she spends her days constantly repeating a video of Allison.
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Mouse and new WP program join Microsoft product lineup, InfoWorld, May 30, 1983 Visi On used two mouse drivers. First, loaded in text mode, made mouse registers accessible to the embedded driver, which translated coordinates to cursor position. This internal driver, built-in as a subroutine into VISIONXT.EXE, required Mouse Systems PC-Mouse pointing device.
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A qsort function was implemented by Lee McMahon in 1972. It was in place in Version 3 Unix as a library function, but was then an assembler subroutine. A C version, with roughly the interface of the standard C version, was in-place in Version 6 Unix. It was rewritten in 1983 for BSD.
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VOS has always been a network-aware operating system. Virtually every system call in the native API has a parameter that determines what computer the operation affects. If the operation isn't local, it is redirected to the target computer via remote subroutine call. For example, file names are parsed to indicate which computer the file resides on.
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A filter is a computer program or subroutine to process a stream, producing another stream. While a single filter can be used individually, they are frequently strung together to form a pipeline. Some operating systems such as Unix are rich with filter programs. Windows 7 and later are also rich with filters, as they include Windows PowerShell.
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One of the key steps in the algorithm is a subroutine to compute the common d-neighborhood of three l-mers. Let x, y, z be any three l-mers. To compute Bd(x, y, z), PMS5 represents Bd(x) as a tree Td(x). Each node in this tree represents an l-mer in Bd(x).
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Code Complete is a software development book, written by Steve McConnell and published in 1993 by Microsoft Press, encouraging developers to continue past code-and-fix programming and the big design up front and waterfall models. It is also a compendium of software construction techniques, which include techniques from naming variables to deciding when to write a subroutine.
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Also, `fcntl` locks are not inherited by a child process. The `fcntl` close semantics are particularly troublesome for applications that call subroutine libraries that may access files. Neither of these "bugs" occurs using real `flock`-style locks. Preservation of the lock status on open file descriptors passed to another process using a Unix domain socket is implementation dependent.
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A module here refers to a subroutine of any kind, i.e. a set of one or more statements having a name and preferably its own set of variable names. ;Content coupling (high): Content coupling is said to occur when one module uses the code of another module, for instance a branch. This violates information hiding – a basic design concept.
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The first sixteen locations in program memory had special functions. Location 0 supported the single-level of subroutine call, automatically being updated with a return address on every jump instruction. The next fifteen locations could used as index registers by one of the addressing modes. A programmable, six-bit relay register was intended for use by external instruments.
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Use of a user-defined function sq(x) in Microsoft Excel. The named variables x & y are identified in the Name Manager. The function sq is introduced using the Visual Basic editor supplied with Excel. Subroutine in Excel calculates the square of named column variable x read from the spreadsheet, and writes it into the named column variable y.
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It would also renumber all references to those line numbers so they would continue to work properly. In a large program containing subroutines, each subroutine would usually start at a line number sufficiently large to leave room for expansion of the main program (and previous subroutines). For example, subroutines might begin at lines 10000, 20000, 30000, etc.
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Indirect addressing was almost as good as index registers. The instruction set supported both relative (to the current P register) and absolute. The original instruction set did not have a subroutine call instruction and could only address one bank of memory. In the 160-A model, a "return jump" and a memory bank-switch instruction was added.
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The programming model had two stacks, one for the register stack, and one for subroutine local variables. One grew up from a designated address in the middle of the address space, and the other grew down from the top of the user mode address space. The 90x could accommodate four memory boards, initially holding 1 MB each.
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The machine had a large repertoire of instructions including square root, MAX, MIN and sine. Conditional tests included tests for infinity. When delivered to ETH Zurich in 1950 the machine had a conditional branch facility added and could print on a Mercedes typewriter. There were two program tapes where the second could be used to hold a subroutine.
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One-pass compilers are smaller and faster than multi-pass compilers. One-pass compilers are unable to generate as efficient programs as multi-pass compilers due to the limited scope of available information. Many effective compiler optimizations require multiple passes over a basic block, loop (especially nested loops), subroutine, or entire module. Some require passes over an entire program.
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Most modern implementations of a subroutine call use a call stack, a special case of the stack data structure, to implement subroutine calls and returns. Each procedure call creates a new entry, called a stack frame, at the top of the stack; when the procedure returns, its stack frame is deleted from the stack, and its space may be used for other procedure calls. Each stack frame contains the private data of the corresponding call, which typically includes the procedure's parameters and internal variables, and the return address. The call sequence can be implemented by a sequence of ordinary instructions (an approach still used in reduced instruction set computing (RISC) and very long instruction word (VLIW) architectures), but many traditional machines designed since the late 1960s have included special instructions for that purpose.
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For such programs, the call stack mechanism could save significant amounts of memory. Indeed, the call stack mechanism can be viewed as the earliest and simplest method for automatic memory management. However, another advantage of the call stack method is that it allows recursive subroutine calls, since each nested call to the same procedure gets a separate instance of its private data.
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The following LOOP program sets the value of the variable x_0 to the product of the variables x_1 and x_2. LOOP x1 DO x0 := x0 \+ x2 END This multiplication program uses the syntax introduced by the addition subroutine from the previous example. The multiplication is performed here by adding the value of x_2 a total of x_1 times, storing results in x_0.
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META II is a domain-specific programming language for writing compilers. It was created in 1963-1964 by Dewey Val Schorre at UCLA. META II uses what Schorre called syntax equations. Its operation is simply explained as: > Each syntax equation is translated into a recursive subroutine which tests > the input string for a particular phrase structure, and deletes it if > found.
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The subroutine call stack can be up to 10 deep. Both GOTO lines and subroutines can be addressed indirectly via line number calculation. FOR/NEXT structures can be nested up to eight times. A single one and/or two dimensional array is supported however array memory space must be reserved (subtracted) from the 1,680 character program space via the DEFM command.
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The matching problem can be generalized by assigning weights to edges in G and asking for a set M that produces a matching of maximum (minimum) total weight: this is the maximum weight matching problem. This problem can be solved by a combinatorial algorithm that uses the unweighted Edmonds's algorithm as a subroutine. Kolmogorov provides an efficient C++ implementation of this.
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In 1991, a features war between B32 and one of its competitors, Transoft's Universal Business Basic, saw major improvements to the B32 language. B32 added a Bluebird Business Basic emulation mode, made line numbers optional, and added subroutine calls by name with parameter passing. Transoft had greater financial resources than B32, and more effective marketing. It purchased B32 in 1992.
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The Programmed Instructions, or PINS, were designed to improve the density of subroutine calls; a single 32-bit word called a routine and passed a single parameter. There were sixteen global PINS, hard-wired to key operating system routines. A further 48 PINS were available for user programs. The system was primarily intended to be used by end-user programmers.
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Original development of the Harwell Subroutine Library began in 1963 by Mike Powell and Mike Hopper for internal use on an IBM mainframe at AERE Harwell. Early contributors also included Alan Curtis. With a spreading reputation, the Library was distributed externally for the first time in 1964 upon request. The first library catalog (AERE Report M-1748) was released in 1966.
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In systems that use an OS user programs have to request memory blocks in order to perform an operation. After this operation (e.g. a subroutine) is completed, the program is expected to free up all the memory blocks allocated for it in order to make it available to other programs for use. In programming languages without a garbage collector (e.g.
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The difference between this sketch and the actual proof is that in the actual proof, the computable function halts does not directly take a subroutine as an argument; instead it takes the source code of a program. The actual proof requires additional work to handle this issue. Moreover, the actual proof avoids the direct use of recursion shown in the definition of g.
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Another is to use the BIND option: SUBROUTINE f() BIND(C,NAME="f") END SUBROUTINE In C, most compilers also mangle static functions and variables (and in C++ functions and variables declared static or put in the anonymous namespace) in translation units using the same mangling rules as for their non-static versions. If functions with the same name (and parameters for C++) are also defined and used in different translation units, it will also mangle to the same name, potentially leading to a clash. However, they will not be equivalent if they are called in their respective translation units. Compilers are usually free to emit arbitrary mangling for these functions, because it is illegal to access these from other translation units directly, so they will never need linking between different object code (linking of them is never needed).
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A subroutine call or method invocation will not exit until the invoked computation has terminated. Asynchronous message-passing, by contrast, can result in a response arriving a significant time after the request message was sent. A message-handler will, in general, process messages from more than one sender. This means its state can change for reasons unrelated to the behavior of a single sender or client process.
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To merge two binomial trees of the same order, first compare the root key. Since 7>3, the black tree on the left (with root node 7) is attached to the grey tree on the right (with root node 3) as a subtree. The result is a tree of order 3. The operation of merging two heaps is used as a subroutine in most other operations.
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Cousin to return statements are yield statements: where a return causes a subroutine to terminate, a yield causes a coroutine to suspend. The coroutine will later continue from where it suspended if it is called again. Coroutines are significantly more involved to implement than subroutines, and thus yield statements are less common than return statements, but they are found in a number of languages.
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The ENIAC was programmed using subroutines, nested loops, and indirect addressing for both data locations and jump destinations. During her work programming the ENIAC, Antonelli is credited with the invention of the subroutine. Her colleague, Jean Jennings, recalled when Antonelli proposed the idea to solve the problem where the logical circuits did not have enough capacity to compute some trajectories. The team collaborated on the implementation.
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In an interpreter, there is no output. Code is created a line at a time, executed, and then discarded. Threaded code is a formatting style for compiled code that minimizes memory use. Instead of writing out every step of an operation at its every occurrence in the program, as was common in macro assemblers for instance, the compiler writes each common bit of code into a subroutine.
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The index and codes are chosen by measuring the frequency of calls to each subroutine in the code. Frequent calls are given the shortest codes. Operations with approximately equal frequencies are given codes with nearly equal bit-lengths. Most Huffman-threaded systems have been implemented as direct-threaded Forth systems, and used to pack large amounts of slow-running code into small, cheap microcontrollers.
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Connections are held in an array. On each call, uIP tries to serve a connection, making a subroutine call to application code that responds to, or sends data. The size of the connection array is a number that can be adjusted when uIP is recompiled. uIP is fully compliant with the RFCs that define TCP, UDP and IP. It also implements the mandatory maintenance protocol ICMP.
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These subroutine libraries allowed programmers to concentrate on their specific problems and avoid re-implementing well-known algorithms. The library routines would also be better than average implementations; matrix algorithms, for example, might use full pivoting to get better numerical accuracy. The library routines would also have more efficient routines. For example, a library may include a program to solve a matrix that is upper triangular.
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Because the internal stack can contain only a finite number of registers, it may be necessary to store a part of the stack in memory. This is implemented with the special registers rO and rS which record which part of the local register stack is in memory and which part is still in local physical registers. The register stack provides for fast subroutine linkage.
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As in JOSS, CAL supported the command to branch to a provided part or step, as in or , and for subroutine calls, as in to perform the entire part, or to run that single step and then return. The later syntax was useful when there were many small subroutines as they could be implemented on a single line without an associated or similar concept.
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WP 34S with parallel operator (`∥`) on the key. Suggested already by Kent E. Erickson as a subroutine in digital computers in 1959, the parallel operator is implemented as a keyboard operator on the Reverse Polish Notation (RPN) scientific calculators WP 34S since 2008 as well as on the WP 34C and WP 43S since 2015, allowing to solve even cascaded problems with few keystrokes like .
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Threaded code passes all arguments on the stack. All return values are returned on the stack. This makes naive implementations slower than calling conventions that keep more values in registers. However, threaded code implementations that cache several of the top stack values in registers—in particular, the return address—are usually faster than subroutine calling conventions that always push and pop the return address to the stack.
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The programmed operator facility allows the instruction code field to indicate a call to a vector of subroutine addresses. The six bit instruction code allows up to 64 programmed operators (octal 00 through 77). If the P bit is set, an instruction code of xx is treated as a call to location 1xx (octal). The location of the POP instruction is saved in location zero.
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Its use immediately made possible data transmission at 9600 bits per second – four times the highest previously attainable speed. Shortly thereafter, the relays were replaced with transistor switches, then in succeeding years the equalizer was implemented with a special purpose integrated circuit. Today adaptive equalization is built into almost every modem and is simply a subroutine in the instruction program for an embedded microprocessor.
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Whatever arguments are passed are available to the subroutine in the special array `@_`. The elements of `@_` are references to the actual arguments; changing an element of `@_` changes the corresponding argument. Elements of `@_` may be accessed by subscripting it in the usual way. $_[0], $_[1] However, the resulting code can be difficult to read, and the parameters have pass-by- reference semantics, which may be undesirable.
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In computer science, message passing is a technique for invoking behavior (i.e., running a program) on a computer. The invoking program sends a message to a process (which may be an actor or object) and relies on that process and its supporting infrastructure to then select and run some appropriate code. Message passing differs from conventional programming where a process, subroutine, or function is directly invoked by name.
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Variables can be local (accessible throughout a subroutine), global (accessible throughout a module) or public (accessible throughout a program). All variables are typeless. This means you can write the following code: Sub App_Start numA = "Five " numB = "5" numC = 6 SUM1 = numA & numB 'remark: = "Five 5" SUM2 = numB + numC 'remark: = 11 End Sub There is no need to declare variables explicitly. Subroutines (called "Sub") are the most basic unit of code.
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A basic subroutine within this procedure merges pairs of binomial trees of the same order. This may be done by comparing the keys at the roots of the two trees (the smallest keys in both trees). The root node with the larger key is made into a child of the root node with the smaller key, increasing its order by one: function mergeTree(p, q) if p.root.key <= q.root.
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The Fortran subroutine NLPQLP, a newer version of NLPQL, solves smooth nonlinear programming problems by a sequential quadratic programming (SQP) algorithm. The new version is specifically tuned to run under distributed systems. In case of computational errors, caused for example by inaccurate function or gradient evaluations, a non-monotone line search is activated. The code is easily transformed to C by f2c and is widely used in academia and industry.
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IA-64 Linux Kernel: Design and Implementation, 4.7 Switching Address SpacesOperating Systems, 5.6 The Context Switch, p. 118 Furthermore, analogous context switching happens between user threads, notably green threads, and is often very lightweight, saving and restoring minimal context. In extreme cases, such as switching between goroutines in Go, a context switch is equivalent to a coroutine yield, which is only marginally more expensive than a subroutine call.
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A microkernel is a logical step up from a real-time OS. The usual arrangement is that the operating system kernel allocates memory and switches the CPU to different threads of execution. User- mode processes implement major functions such as file systems, network interfaces, etc. In general, microkernels succeed when task switching and intertask communication is fast and fail when they are slow. Exokernels communicate efficiently by normal subroutine calls.
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Dissecting the Collatz sequence starting from 6 J has the usual facilities for stopping on error or at specified places within verbs. It also has a unique visual debugger, called Dissect, that gives a 2-D interactive display of the execution of a single J sentence. Because a single sentence of J performs as much computation as an entire subroutine in lower-level languages, the visual display is quite helpful.
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Graph traversal is a subroutine in most graph algorithms. The goal of a graph traversal algorithm is to visit (and / or process) every node of a graph. Graph traversal algorithms, like breadth-first search and depth-first search, are analyzed using the von Neumann model, which assumes uniform memory access cost. This view neglects the fact, that for huge instances part of the graph resides on disk rather than internal memory.
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The PDP-14 was a specialized computer from Digital Equipment Corporation. Unlike DEC's general-purpose computers, which are simply called computers, this unit had no data memory or data registers and was intended as an industrial controller a programmable logic controller (PLC). Its instructions can test Boolean input signals, set or clear Boolean output signals, jump conditional or unconditionally, or call a subroutine. I/O is line voltage.
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The SPICE system includes software referred to as The SPICE Toolkit, used for reading the SPICE data files and computing geometric parameters based on data from those files. These tools are provided as subroutine libraries in four programming languages: C, FORTRAN, IDL, MATLAB and Java Native Interface. Third parties offer Python and Ruby interfaces to the C-language Toolkit. The Toolkits also include a number of utility and application programs.
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BEFLIX was developed on the IBM 7090 mainframe computer using a Stromberg-Carlson SC2040 microfilm recorder for output. The programming environment targeted by BEFLIX consisted of a FORTRAN II implementation with FORTRAN II Assembly Program (FAP) macros. The first version of BEFLIX was implemented through the FAP macro facility. A later version targeting FORTRAN IV resembled a more traditional subroutine library and lost some of the unique flavor to the language.
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While a backreference provides a mechanism to refer to that part of the subject that has previously matched a subpattern, a subroutine provides a mechanism to reuse an underlying previously defined subpattern. The subpattern's options, such as case independence, are fixed when the subpattern is defined. (a.c)(?1) would match "aacabc" or "abcadc", whereas using a backreference (a.c)\1 would not, though both would match "aacaac" or "abcabc".
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In denotational semantics a partial function is considered as returning the bottom element when it is undefined. In computer science a partial function corresponds to a subroutine that raises an exception or loops forever. The IEEE floating point standard defines a not-a- number value which is returned when a floating point operation is undefined and exceptions are suppressed, e.g. when the square root of a negative number is requested.
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Iain S. Duff is a British mathematician and computer scientist, known for his work in numerical methods and software for solving problem with sparse matrices, in particular the Harwell Subroutine Library. From 1986–2009, he was the Group Leader of Numerical Analysis at Harwell Laboratory, which has moved in 1990 to the Rutherford Appleton Laboratory. He is also the Project Leader for the Parallel Algorithms Group at CERFACS in Toulouse.
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The hybrid was developed as the heart of the new 9825 desktop computer. The later 9845 workstation added an MMU chip. These were the forerunners of personal computers and technical workstations. The major differences between the original 2116 architecture and the BPC microprocessor are a completely redesigned I/O structure, the removal of multiple levels of indirect addressing, and the provision of a stack register for subroutine call and return.
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Most modern computers have two crystal oscillators, one for the real-time clock and one for the primary CPU clock; truerand exploits this fact. It uses an operating system service that sets an alarm, running off the real-time clock. One subroutine sets that alarm to go off in one clock tick (usually 1/60th of a second). Another then enters a while loop waiting for the alarm to trigger.
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RISC-V's subroutine call (jump and link) places its return address in a register. This is faster in many computer designs, because it saves a memory access compared to systems that push a return address directly on a stack in memory. has a 20-bit signed (2's complement) offset. The offset is multiplied by 2, then added to the PC to generate a relative address to a 32-bit instruction.
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One of the ways to find this type of error is to put out the program's variables to a file or on the screen in order to determine the error's location in code. Although this will not work in all cases, for example when calling the wrong subroutine, it is the easiest way to find the problem if the program uses the incorrect results of a bad mathematical calculation.
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Before a subroutine returns, it jumps to the location immediately preceding its entry point so that after the SEP "return" instruction returns control to the caller, the register will be pointing to the right value for next usage. (the processor always increments the PC after reference and usage (retrieving the next instruction to execute), so this technique works as noted) An interesting variation of this scheme is to have two or more subroutines in a ring so that they are called in round robin order. On early hobbyist computers, tricks and techniques like this were commonly used in the horizontal refresh interrupt to reprogram the scan line address to repeat each scan line four times for the video controller. One well-known and often-used routine is known as SCRT (Standard CALL and RETURN Technique), which allows general purpose subroutine Call and Return, including passing of parameters "in line", and nested subroutines using a stack.
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If the compiler saves registers on the stack before calling a subroutine and restores them when returning, consecutive calls to subroutines may have redundant stack instructions. Suppose the compiler generates the following Z80 instructions for each procedure call: PUSH AF PUSH BC PUSH DE PUSH HL CALL _ADDR POP HL POP DE POP BC POP AF If there were two consecutive subroutine calls, they would look like this: PUSH AF PUSH BC PUSH DE PUSH HL CALL _ADDR1 POP HL POP DE POP BC POP AF PUSH AF PUSH BC PUSH DE PUSH HL CALL _ADDR2 POP HL POP DE POP BC POP AF The sequence POP regs followed by PUSH for the same registers is generally redundant. In cases where it is redundant, a peephole optimization would remove these instructions. In the example, this would cause another redundant POP/PUSH pair to appear in the peephole, and these would be removed in turn.
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A "return-to-libc" attack is a computer security attack usually starting with a buffer overflow in which a subroutine return address on a call stack is replaced by an address of a subroutine that is already present in the process’ executable memory, bypassing the no-execute bit feature (if present) and ridding the attacker of the need to inject their own code. The first example of this attack in the wild was contributed by Alexander Peslyak on the Bugtraq mailing list in 1997. On POSIX-compliant operating systems the C standard library ("`libc`") is commonly used to provide a standard runtime environment for programs written in the C programming language. Although the attacker could make the code return anywhere, `libc` is the most likely target, as it is almost always linked to the program, and it provides useful calls for an attacker (such as the `system` function used to execute shell commands).
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An integer sorting algorithm is said to be non-conservative if it requires a word size that is significantly larger than .; . As an extreme instance, if , and all keys are distinct, then the set of keys may be sorted in linear time by representing it as a bitvector, with a 1 bit in position when is one of the input keys, and then repeatedly removing the least significant bit.. The non-conservative packed sorting algorithm of uses a subroutine, based on Ken Batcher's bitonic sorting network, for merging two sorted sequences of keys that are each short enough to be packed into a single machine word. The input to the packed sorting algorithm, a sequence of items stored one per word, is transformed into a packed form, a sequence of words each holding multiple items in sorted order, by using this subroutine repeatedly to double the number of items packed into each word.
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A decision problem H is NP-hard when for every problem L in NP, there is a polynomial-time many-one reduction from L to H. An equivalent definition is to require that every problem L in NP can be solved in polynomial time by an oracle machine with an oracle for H. Informally, an algorithm can be thought of that calls such an oracle machine as a subroutine for solving H and solves L in polynomial time if the subroutine call takes only one step to compute. Another definition is to require that there be a polynomial-time reduction from an NP-complete problem G to H. As any problem L in NP reduces in polynomial time to G, L reduces in turn to H in polynomial time so this new definition implies the previous one. Awkwardly, it does not restrict the class NP-hard to decision problems, and it also includes search problems or optimization problems.
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Applications including efficient spherical harmonic expansion, analyzing certain Markov processes, robotics etc. ; Quantum FFTs: Shor's fast algorithm for integer factorization on a quantum computer has a subroutine to compute DFT of a binary vector. This is implemented as sequence of 1- or 2-bit quantum gates now known as quantum FFT, which is effectively the Cooley–Tukey FFT realized as a particular factorization of the Fourier matrix. Extension to these ideas is currently being explored.
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Oberon (Oberon-07) has a return clause instead of a return statement. The return clause is placed after the last statement of the procedure body. This enables compile-time checking of proper return and return value from the procedure. Some expression-oriented programming language, such as Lisp, Perl and Ruby, allow the programmer to omit an explicit return statement, specifying instead that the last evaluated expression is the return value of the subroutine.
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The cdecl (which stands for C declaration) is a calling convention that originates from Microsoft's compiler for the C programming language and is used by many C compilers for the x86 architecture. In cdecl, subroutine arguments are passed on the stack. Integer values and memory addresses are returned in the EAX register, floating point values in the ST0 x87 register. Registers EAX, ECX, and EDX are caller-saved, and the rest are callee-saved.
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The request processor consists of the server process' main loop and a number of state machines. State machines are based on a simple language developed for PVFS that manage concurrency within the server and client. A state machine consists of a number of states, each of which either runs a C state action function or calls a nested (subroutine) state machine. In either case return codes select which state to go to next.
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The subroutine pushes the result of the expression onto the arithmetic stack (in this case, the line number). verifies no other text follows the expression and gives an error if it does. pops the number from the stack and transfers execution (GOes TO) the corresponding line number, if it exists. The following table gives a partial list of the 32 commands of the virtual machine in which the first Tiny BASIC interpreter was written.
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Early implementations operated by switching the terminal into erase mode and re- executing the entire case that had matched. Some later implementations buffered the output produced during judging so that this output could be erased. The `join` command was a unique form of subroutine call. It was defined as being equivalent to textual substitution of the body of the joined unit in place of the join command itself (page 21, 1973 TUTOR User's Memo).
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In addition watershed groundwater may also be included. The model is termed "physically based" if its parameters can be measured in the field. Often models have separate modules to address individual steps in the simulation process. The most common module is a subroutine for calculation of surface runoff, allowing variation in land use type, topography, soil type, vegetative cover, precipitation and land management practice (such as the application rate of a fertilizer).
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In many programming languages, a function prototype is the declaration of a subroutine or function (and should not be confused with software prototyping). This term is rather C/C++-specific; other terms for this notion are signature, type and interface. In prototype-based programming (a form of object-oriented programming), new objects are produced by cloning existing objects, which are called prototypes. The term may also refer to the Prototype Javascript Framework.
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The default set-up was 22 register and 512 steps. From there one could trade 8 steps for one additional register or 80 steps for 11 register with the 11th register begin a so-called "F" register. Like its predecessor the FX-602P series supported 10 labels for programs and subroutines called P0 .. P9. Each program or subroutine could have up to 10 local labels called LBL0 .. LBL9 for jumps and branches.
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Procedural programming is a programming paradigm, derived from structured programming, based on the concept of the procedure call. Procedures (a type of routine or subroutine) simply contain a series of computational steps to be carried out. Any given procedure might be called at any point during a program's execution, including by other procedures or itself. The first major procedural programming languages appeared circa 1957–1964, including Fortran, ALGOL, COBOL, PL/I and BASIC.
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In computer programming with the language Scheme, the subroutine or function call-with-current-continuation, abbreviated call/cc, is used as a control flow operator. It has been adopted by several other programming languages. Taking a function `f` as its only argument, `(call/cc f)` within an expression is applied to the current continuation of the expression. For example `((call/cc f) e2)` is equivalent to applying `f` to the current continuation of the expression.
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These kernel operations became defined subroutines that math libraries could call. The kernel calls had advantages over hard-coded loops: the library routine would be more readable, there were fewer chances for bugs, and the kernel implementation could be optimized for speed. A specification for these kernel operations using scalars and vectors, the level-1 Basic Linear Algebra Subroutines (BLAS), was published in 1979. BLAS was used to implement the linear algebra subroutine library LINPACK.
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The following C subroutine `max()` returns the maximum value in its argument array `a[]`, provided its length `n` is at least 1. Comments are provided at lines 3, 6, 9, 11, and 13. Each comment makes an assertion about the values of one or more variables at that stage of the function. The highlighted assertions within the loop body, at the beginning and end of the loop (lines 6 and 11), are exactly the same.
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The programmer creates a subroutine which consists of statements, and the computer executes each statement in a linear order. In contrast, fifth-generation programming languages like Golog are working with an abstract model with which the interpreter can generate the sequence of actions. The source code defines the problem and it is up to the solver to find the next action. This approach can facilitate the management of complex problems from the domain of robotics.
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After assessing one's opponent, territorial species usually react with either a flight or flight response. However, in a "blocked escape" scenario, where territory is limited or escape is impossible, this pattern diverges. Upon losing dominance, defeated individuals undergo a change in physical demeanor known as the yielding subroutine of RAB or the involuntary subordinate strategy (ISS). For example, an early study of farmyard fowls found that despite an absence of physical injury, defeated birds seemed to be paralyzed.
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Most programming environments with recursive subroutines use a stack for control flow. This structure typically also stores local variables, including subroutine parameters (in call by value system such as C). Forth often does not have local variables, however, nor is it call-by-value. Instead, intermediate values are kept in another stack, different from the one it uses for return addresses, loop counters, etc. Words operate directly on the topmost values in the first of these two stacks.
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The above code defines a tape file on channel 1 called OUT, a sequential 1301/1302 disk file called DAFILE and a card file called CONSFILE. Any IOCS program must specify the actions that it wishes to perform. In 7070 IOCS this is done with processing macros. 11 22 6 56 01 OPEN CONSFILE,OUT LOOP GET CONSFILE PUT OUT B LOOP CONSEOF CLOSECONSFILE,OUT In some other IOCS packages similar functions are provided by explicit subroutine calls.
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On the contrary, she seemed to be endeared by the sight, and wished both characters a peaceful slumber. She speaks only Japanese, although she has the ability to have other language "modules" installed. Due to problems with her prototype software, Ping does not handle rejection well and can be sent into a berserk rage when "rejected" by her human companions. Largo has triggered her rejection subroutine on two occasions so far,(comic #138,#368) once intentionally.
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Method dispatch in object oriented programming can be thought of as "two dimensional" in the sense that the code executed depends on both the method name and the object in question. This can be contrastedJournal of Object Technology: Context Oriented Programming with procedural programming, where a procedure name resolves directly, or one dimensionally, onto a subroutine, and also to subject oriented programming, where the sender or subject is also relevant to dispatch, constituting a third dimension.
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If it finds it, execution continues with the next IL command. In this case, the system next tests for , skipping to line if it fails (a test for , to see if this is instead a command). If it passes, control continues; in this case, calling an IL subroutine that starts at label , which parses an expression. In Tiny BASIC, (a computed GO TO) is as legal as and is the alternative to the ON-GOTO of larger BASIC implementations.
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DUCS differed from competing products such as Westi and IBM's own CICS in that it was subordinate to the application's mainline program. Westi, for example, was the mainline program and users wrote subroutines to read and write data to and from terminals and discs. This real time paradigm became known as transaction processing. DUCS reversed that model in that it was, in fact, a subroutine package that read from and wrote to monitors, both local and remote.
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Because the algorithm uses only simple for loops, without recursion or subroutine calls, it is straightforward to analyze. The initialization of the count array, and the second for loop which performs a prefix sum on the count array, each iterate at most times and therefore take time. The other two for loops, and the initialization of the output array, each take time. Therefore, the time for the whole algorithm is the sum of the times for these steps, .
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Data seeks the opinion of his friends, including Picard, Guinan (Whoopi Goldberg), Geordi La Forge (LeVar Burton), Commander William Riker (Jonathan Frakes), Deanna Troi (Marina Sirtis) and Worf (Michael Dorn). Data decides to pursue the relationship and goes to D'Sora's cabin with a bunch of flowers, where he informs her that he created a romantic subroutine for the relationship. Meanwhile, the Enterprise is approaching the planet. Picard enters his ready room and finds his belongings scattered on the floor.
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Return-jump allowed simple subroutine calls and bank switching allowed other 4K banks of memory to be addressed, albeit clumsily, up to a total of 32,768 words. The extra memory was expensive and had to live in a separate box as large as the 160 itself. The 160-A model could also accept a multiply/divide unit, which was another large and expensive peripheral box. In the 160 and 160-A, the memory cycle time was 6.4 microseconds.
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The following is a presentation of the basic DSW algorithm in pseudocode, after the Stout–Warren paper.This version does not produce perfectly balanced nodes; Stout and Warren present a modification that does, in which the first call to is replaced by a different subroutine. It consists of a main routine with three subroutines. The main routine is given by # Allocate a node, the "pseudo-root", and make the tree's actual root the right child of the pseudo-root.
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Often, subroutines accessible via the operating system kernel are not reentrant. Hence, interrupt service routines are limited in the actions they can perform; for instance, they are usually restricted from accessing the file system and sometimes even from allocating memory. This definition of reentrancy differs from that of thread-safety in multi-threaded environments. A reentrant subroutine can achieve thread-safety, but being reentrant alone might not be sufficient to be thread-safe in all situations.
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Given an array A of n elements with values A0 ... An−1, and target value T, the following subroutine uses multiplicative binary search to find the index of T in A. # Set i to 0 # if i ≥ n, the search terminates unsuccessful. # if Ai = T, the search is done; return i. # if Ai < T, set i to 2×i + 1 and go to step 2. # if Ai > T, set i to 2×i + 2 and go to step 2.
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The Criterion series provided a virtual machine architecture which allowed different machine architectures running under the same operating system. The initial offering provided a Century virtual machine which was instruction compatible with the Century series and a COBOL virtual machine designed to optimize programs written in COBOL. Switching between virtual machines was provided by a virtual machine indicator in the subroutine call mechanism. This allowed programs written in one virtual machine to use subroutines written for another.
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CodeAnalyst is built on OProfile for the Linux platform and is available as a free download. The GUI assists in various kinds of code profiling including time based profiling, hardware event-based profiling, instruction-based profiling and others. This produces statistics about details such as time spent in each subroutine which can be drilled down to the source code or instruction level. The time taken by the instructions can be indicative of stalls in the pipeline during instruction execution.
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The IBM SSEC, demonstrated in January 1948, had the ability to modify its instructions or otherwise treat them exactly like data. However, the capability was rarely used in practice. In the early days of computers, self-modifying code was often used to reduce use of limited memory, or improve performance, or both. It was also sometimes used to implement subroutine calls and returns when the instruction set only provided simple branching or skipping instructions to vary the control flow.
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This is especially common when the subroutine takes only one argument or for handling the `$self` argument in object-oriented modules. my $x = shift; Subroutines may assign `@_` to a hash to simulate named arguments; this is recommended in Perl Best Practices for subroutines that are likely to ever have more than three parameters. Damian Conway, Perl Best Practices , p.182 sub function1 { my %args = @_; print "'x' argument was '$args{x}' "; } function1( x => 23 ); Subroutines may return values.
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GdkFrameClock was added in GTK 3.8 While GTK applications remain mainloop driven (cf. Glib event loop), meaning the application is idle inside this main loop most of the time and just waits for something to happen and then calls the appropriate subroutine when it does, GdkFrameClock adds an additional mechanism, that gives a "pulse" to the application. It tells the application when to update and repaint a window. The beat rate can be synchronized with the monitor refresh rate.
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A filtered-popping recursive transition network (FPRTN),Javier M. Sastre, "Efficient parsing using filtered-popping recursive transition networks", Lecture Notes in Artificial Intelligence, 5642:241-244, 2009 or simply filtered-popping network (FPN), is a recursive transition network (RTN) William A. Woods, "Transition network grammars for natural language analysis", Communications of the ACM, ACM Press, 13:10:591-606, 1970 extended with a map of states to keys where returning from a subroutine jump requires the acceptor and return states to be mapped to the same key. RTNs are finite-state machines that can be seen as finite-state automata extended with a stack of return states; as well as consuming transitions and \varepsilon-transitions, RTNs may define call transitions. These transitions perform a subroutine jump by pushing the transition's target state onto the stack and bringing the machine to the called state. Each time an acceptor state is reached, the return state at the top of the stack is popped out, provided that the stack is not empty, and the machine is brought to this state.
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The programming capabilities of the TI-57 were similar to a primitive macro assembler. Any keystroke could be stored, along with some simple program flow control commands and conditional tests. These included: GTO (GoTO): Causes program pointer to jump immediately to a Label (0-9) or to a specific program step (00 to 49). SBR (SuBRoutine): Causes a program to jump to a Label, and on encountering an Inv SBR command, continue executing at the instruction immediately following the original SBR.
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In compiler optimization, escape analysis is a method for determining the dynamic scope of pointers where in the program a pointer can be accessed. It is related to pointer analysis and shape analysis. When a variable (or an object) is allocated in a subroutine, a pointer to the variable can escape to other threads of execution, or to calling subroutines. If an implementation uses tail call optimization (usually required for functional languages), objects may also be seen as escaping to called subroutines.
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To remove the need for self-modifying code, computer designers eventually provided an indirect jump instruction, whose operand, instead of being the return address itself, was the location of a variable or processor register containing the return address. On those computers, instead of modifying the subroutine's return jump, the calling program would store the return address in a variable so that when the subroutine completed, it would execute an indirect jump that would direct execution to the location given by the predefined variable.
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Besides physical resources, information is often reused, notably program code for the software that drives computers and the Internet, but also the documentation that explains how to use every modern device. And it is proposed as a way to improve education by assembling a great library of shareable learning objects that can be reused in learning management systems. Software reuse grew out of the standard subroutine libraries of the 1960s. It is the main principle of today's object- oriented programming.
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The address is computed as the sum of the 8-bit accumulator and a 16-bit register (PC or DPTR). Special jump and call instructions ( and ) slightly reduce the size of code that accesses local (within the same 2 KB) program memory.ACALL is a 2-byte subroutine calling instruction, it can access locations within the same 2KB segment of memory. The absolute memory address is formed by the high 5 bits of the PC and the 11 bits defined by the instruction.
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W. A. Woods in "Transition Network Grammars for Natural Language Analysis" claims that by adding a recursive mechanism to a finite state model, parsing can be achieved much more efficiently. Instead of building an automaton for a particular sentence, a collection of transition graphs are built. A grammatically correct sentence is parsed by reaching a final state in any state graph. Transitions between these graphs are simply subroutine calls from one state to any initial state on any graph in the network.
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PYMOM is a composite body of techniques that claims, in its digital form, to incorporate (to a greater or lesser degree): spaced repetition, non-failure redundant subroutine, chromatics, positive reinforcement, the Von Restorff effect, picture association, selective musical tonality, kinesthetics, the serial-position effect and meditation. There are two branches of this methodology: #the historical, physical incarnation, the Triangular Movement Cycle and #the digitized version, incorporating the significant addition of the aforementioned educational methods and theories, Pythagorean Method of Memorization.
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Each reader/interpreter or output writer was a separate operating system task in its own partition or region.However, RJE and the later CRJE called the Reader/Interpreter as a subroutine and performed the functions of an output writer within its own partition/region. A system with a large number of readers, printers, and punches might have a large number of spooling tasks. HASP was developed by IBM Federal Systems Division contractors at the Lyndon B. Johnson Space Center in Houston.
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This is because message passing is essentially a subroutine call, but with three added overheads: dynamic memory allocation, parameter copying, and dynamic dispatch. Obtaining memory from the heap and copying parameters for message passing may involve significant resources that far exceed those needed for the state change. Accessors (or getters) that merely return the values of private member variables also depend on similar message passing subroutines, instead of using a more direct assignment (or comparison), adding to total path length.
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Also, as executing or always vectors the processor to the same address, simple code may be used to preserve the registers on the stack prior to turning control over to the requested service. However, this programming model will result in somewhat slower execution as compared to calling a service as a subroutine, primarily a result of the stack activity that occurs with any interrupt. Also, interrupt requests will have been disabled by executing or , requiring that the operating system re-enable them.
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A major section of the software is a custom graphics language, which is an early scalable vector graphics format. Hundreds of images of objects and locations are drawn in the game using this custom tool. Perspective of a limited kind is achieved by permitting images to be drawn scaled down within another image. For example, a castle model would be designed for close up view, but could also be drawn as a subroutine for a distant castle in a desert.
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Piece of code from a module of the Linux kernel, which uses snake case for identifiers. Snake case (stylized as snake_case) refers to the style of writing in which each space is replaced by an underscore (_) character, and the first letter of each word written in lowercase. It is a commonly used naming convention in computing, for example for variable and subroutine names, and for filenames. One study has found that readers can recognize snake case values more quickly than camel case.
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AA featured explicitly typed variables, subroutines, and functions. It omitted some ALGOL features such as passing parameters by name, which in ALGOL 60 means passing the memory address of a short subroutine to recalculate a parameter each time it is mentioned. The AA compiler generated range-checking for array accesses, and allowed an array to have dimensions that were determined at runtime, i.e., an array could be declared as `_integer_ _array_ Thing (i:j)`, where `i` and `j` were calculated values.
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A driver wrapper is a subroutine in a software library that functions as an adapter between an operating system and a driver, such as a device driver, that was not designed for that operating system. It can enable the use of devices for which no drivers for the particular operating system are available. In particular, Microsoft Windows is the dominant family of operating systems for IBM PC compatible computers, and many devices are supplied with drivers for Windows but not other operating systems.
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Instructions to perform standard fixed and floating point operations were software subroutines and programs were lists of links and operators to those subroutines. For example, the "subtract" subroutine had to form the ones' complement of the subtrahend and add it. Multiplication required successive shifting and conditional adding. In the AN/UYK-1 instruction set, the machine- language instructions had two operators that could simultaneously manipulate the arithmetic registers—for example, complementing the contents of one register while loading or storing another.
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Programmers may decide to create internal abstractions so that certain parts of their program can be reused, or may create custom libraries for their own use. Some characteristics that make software more easily reusable are modularity, loose coupling, high cohesion, information hiding and separation of concerns. For newly written code to use a piece of existing code, some kind of interface, or means of communication, must be defined. These commonly include a "call" or use of a subroutine, object, class, or prototype.
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With features like, Record Structure and subroutines, it allows us to get data from database and manipulate it by storing in a temporary structure; execute a particular section of the code, if required using a subroutine. Complete for CCL (Cerner Command Language) is provided by Cerner Corporation. Discern Explorer provides several applications that can be used to create, execute, and analyze ad hoc queries, reports and programs. These applications provide flexibility in the skill set needed to build programs and design reports.
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If the uppermost bit was set to one, this was an Extracode and was implemented as a special kind of subroutine jump to a location in the fixed store (ROM), its address being determined by the other nine bits. About 250 extracodes were implemented, of the 512 possible. Extracodes were what would be called software interrupt or trap today. They were used to call mathematical procedures which would have been too inefficient to implement in hardware, for example sine, logarithm, and square root.
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These front-end systems support their own command language of "device commands", usually lines prefixed with a special character such as a percent-sign (%), to allow the user to configure and control the connections. Data Concentrator User's Guide, David L. Mills, Jack L. Di Giuseppe, and W. Scott Gerstenberger, CONCOMP Project, University of Michigan, April 1970 The $CONTROL command and programs running on MTS can use the CONTROL subroutine to issue device commands to front-end and network control units.
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For instance, in later development, a return statement could be overlooked by a developer, and an action which should be performed at the end of a subroutine (e.g., a trace statement) might not be performed in all cases. Languages without a return statement, such as standard Pascal don't have this problem. Some languages, such as C++ and Python, employ concepts which allow actions to be performed automatically upon return (or exception throw) which mitigates some of these issues – these are often known as "try/finally" or similar.
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Functionality like these "finally" clauses can be implemented by a goto to the single return point of the subroutine. An alternative solution is to use the normal stack unwinding (variable deallocation) at function exit to unallocate resources, such as via destructors on local variables, or similar mechanisms such as Python's "with" statement. Some early implementations of languages such as the original Pascal and C restricted the types that can be returned by a function (e.g., not supporting record or struct types) to simplify their compilers.
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In class-based object-oriented programming, a constructor (abbreviation: ctor) is a special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. A constructor resembles an instance method, but it differs from a method in that it has no explicit return type, it is not implicitly inherited and it usually has different rules for scope modifiers. Constructors often have the same name as the declaring class.
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One way of implementing iterators is to use a restricted form of coroutine, known as a generator. By contrast with a subroutine, a generator coroutine can yield values to its caller multiple times, instead of returning just once. Most iterators are naturally expressible as generators, but because generators preserve their local state between invocations, they're particularly well-suited for complicated, stateful iterators, such as tree traversers. There are subtle differences and distinctions in the use of the terms "generator" and "iterator", which vary between authors and languages.
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The QNX kernel, `procnto`, contains only CPU scheduling, interprocess communication, interrupt redirection and timers. Everything else runs as a user process, including a special process known as `proc` which performs process creation and memory management by operating in conjunction with the microkernel. This is made possible by two key mechanisms: subroutine-call type interprocess communication, and a boot loader which can load an image containing the kernel and any desired set of user programs and shared libraries. There are no device drivers in the kernel.
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A function pointer, also called a subroutine pointer or procedure pointer, is a pointer that points to a function. As opposed to referencing a data value, a function pointer points to executable code within memory. Dereferencing the function pointer yields the referenced function, which can be invoked and passed arguments just as in a normal function call. Such an invocation is also known as an "indirect" call, because the function is being invoked indirectly through a variable instead of directly through a fixed identifier or address.
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All processors, including TTA processors, include control flow instructions that alter the program counter, which are used to implement subroutines, if-then-else, for-loop, etc. The assembly language for TTA processors typically includes control flow instructions such as unconditional branches (JUMP), conditional relative branches (BNZ), subroutine call (CALL), conditional return (RETNZ), etc. that look the same as the corresponding assembly language instructions for other processors. Like all other operations on a TTA machine, these instructions are implemented as "move" instructions to a special function unit.
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Most of the frame of the current procedure is no longer needed, and can be replaced by the frame of the tail call, modified as appropriate (similar to overlay for processes, but for function calls). The program can then jump to the called subroutine. Producing such code instead of a standard call sequence is called tail call elimination or tail call optimization. Tail call elimination allows procedure calls in tail position to be implemented as efficiently as goto statements, thus allowing efficient structured programming.
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Die of Intersil 6100. The 6100 is a 12-bit CPU that closely emulates the PDP-8 (See PDP-8 for a more complete discussion). It has three primary registers: PC (program counter), 12-bit AC (accumulator), and MQ (Multiplier Quotient). All two-operand instructions read the AC and MQ and write back to the AC. There is no stack pointer; subroutines return to their callers by jumping back into the main code, typically by storing the return address in the first word of the subroutine itself.
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The complexity class \Sigma_2 describes problems of the form :\exists x\forall y\;\psi(x,y) where \psi is any polynomial-time computable predicate. The existential power of the first quantifier in this predicate can be used to guess a correct circuit for SAT, and the universal power of the second quantifier can be used to verify that the circuit is correct. Once this circuit is guessed and verified, the algorithm in class \Sigma_2 can use it as a subroutine for solving other problems.
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Additionally, the performance of these calls is almost free of additional overhead. Today, though almost all programming languages focus on isolating code into subroutines, they do so for code clarity and maintainability, not to save space. Threaded code systems save room by replacing that list of function calls, where only the subroutine address changes from one call to the next, with a list of execution tokens, which are essentially function calls with the call opcode(s) stripped off, leaving behind only a list of addresses. David Frech.
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In computer programming, the return type (or result type) defines and constrains the data type of the value returned from a subroutine or method. In many programming languages (especially statically-typed programming languages such as C, C++, Java) the return type must be explicitly specified when declaring a function. In the Java example: public void setShuma(int n1, int n2) { Shuma = n1 + n2 } public int getShuma() { return Shuma; } the return type is int. The program can therefore rely on the method returning a value of type int.
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Every item of the partition is equal to `p` and is therefore sorted. Consequently, the items of the partition need not be included in the recursive calls to `quicksort`. The best case for the algorithm now occurs when all elements are equal (or are chosen from a small set of elements). In the case of all equal elements, the modified quicksort will perform only two recursive calls on empty subarrays and thus finish in linear time (assuming the `partition` subroutine takes no longer than linear time).
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One of the more subtle features of the SYM-1 was the use of a look up table in the low memory of the 6502. This provided a vectoring function in its operating system to redirect subroutine calls to various input and output drivers, including interrupt servicing. Users were able to develop their own interface routines, and substitute new vectors for the original vectors in the startup UV-EPROM. This seamlessly maintained the normal operation of the board's monitor and languages such as Synertek Systems BASIC.
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On exokernels, libraries shield user applications from the very low level kernel API, and provide abstractions and resource management. IBM's OS/360 and DOS/360 implement most system calls through a library of assembly language macros, although there are a few services with a call linkage. This reflects their origin at a time when programming in assembly language was more common than high-level language usage. IBM system calls were therefore not directly executable by high-level language programs, but required a callable assembly language wrapper subroutine.
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PGPLOT is a device-independent graphics subroutine library written starting in 1983 by Tim Pearson, a professor at Caltech. PGPLOT is written mostly in FORTRAN with a modular output API that allows output to several dozen types of plotting device. PGPLOT has been widely used in the academic and scientific communities, because it provides both low-level (glyph, point, line, and area) plotting primitives and also high-level facilities for drawing graphs. PGPLOT may be redistributed to third parties and modified, but only in binary form.
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Factory Method in LePUS3 In object-oriented programming (OOP), a factory is an object for creating other objects – formally a factory is a function or method that returns objects of a varying prototype or class from some method call, which is assumed to be "new". More broadly, a subroutine that returns a "new" object may be referred to as a "factory", as in factory method or factory function. This is a basic concept in OOP, and forms the basis for a number of related software design patterns.
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The BPU was capable of dispatching multiple instructions to the fixed and floating point instructions queues while it was executing a program flow control instruction (up to four simultaneously and out of order). Speculative branches were also supported by using a prediction bit in the branch instructions, with the results discarded before being saved if the branch was not taken. The alternate instruction would be buffered and discarded if the branch was taken. Consequently, subroutine calls and interrupts are dealt with without incurring branch penalties.
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Further, constructors and initializers may take arguments, while destructors and finalizers generally do not, as they are usually called implicitly. In common usage, a constructor is a method directly called explicitly by user code to create an object, while "destructor" is the subroutine called (usually implicitly, but sometimes explicitly) on object destruction in languages with deterministic object lifetimes – the archetype is C++ – and "finalizer" is the subroutine called implicitly by the garbage collector on object destruction in languages with non-deterministic object lifetime – the archetype is Java. The steps during finalization vary significantly depending on memory management: in manual memory management (as in C++, or manual reference counting), references need to be explicitly destroyed by the programmer (references cleared, reference counts decremented); in automatic reference counting, this also happens during finalization, but is automated (as in Python, when it occurs after programmer- specified finalizers have been called); and in tracing garbage collection this is not necessary. Thus in automatic reference counting, programmer-specified finalizers are often short or absent, but significant work may still be done, while in tracing garbage collectors finalization is often unnecessary.
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The following is a FORTRAN 66 hello world program using Hollerith constants. It assumes that at least four characters per word are supported by the implementation: PROGRAM HELLO1 C INTEGER IHWSTR(3) DATA IHWSTR/4HHELL,4HO WO,3HRLD/ C WRITE (6,100) IHWSTR STOP 100 FORMAT (3A4) END Besides `DATA` statements, Hollerith constants were also allowed as actual arguments in subroutine calls. However, there was no way that the callee could know how many characters were passed in. The programmer had to pass the information explicitly. The hello world program could be written as follows on a machine where four characters are stored in a word: PROGRAM HELLO2 CALL WRTOUT (11HHELLO WORLD, 11) STOP END C SUBROUTINE WRTOUT (IARRAY, NCHRS) C INTEGER IARRAY(1)FORTRAN 66 did not have a way to indicate a variable-sized array. So a '1' was typically used to indicate that the size is unknown. INTEGER NCHRS C INTEGER ICPW DATA ICPW/4/Four characters per word. INTEGER I, NWRDS C NWRDS = (NCHRS + ICPW - 1) /ICPW WRITE (6,100) (IARRAY(I), I=1,NWRDS) RETURN 100 FORMAT (100A4)A count of 100 is a 'large enough' value that any reasonable number of characters can be written.
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If the reference count of a data value drops to 0, then it will be destroyed and its memory is made available for reuse. Other typedefs are Glob Value (GV) which contain named references to various objects, Code Value (CV) which contain a reference to a Perl subroutine, I/O Handler (IO), a reference to regular expression (REGEXP; RV in Perl before 5.11), reference to compiled format for output record (FM) and simple reference which is a special type of scalar that point to other data types (RV).
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In many programming language implementations, all variables declared within a procedure (subroutine, or function) are local to that function; the runtime environment for the program automatically allocates memory for these variables on program execution entry to the procedure, and automatically releases that memory when the procedure is exited. Special declarations may allow local variables to retain values between invocations of the procedure, or may allow local variables to be accessed by other procedures. The automatic allocation of local variables makes recursion possible, to a depth limited by available memory.
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The most fundamental distinction is a scalar context where the calling code expects one value, a list context where the calling code expects a list of values and a void context where the calling code doesn't expect any return value at all. A subroutine can check the context using the `wantarray` function. A special syntax of return without arguments is used to return an undefined value in scalar context and an empty list in list context. The scalar context can be further divided into Boolean, number, string, and various reference types contexts.
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Somewhat similarly to BCR 15,14 (the 24-bit-only form of an unconditional return), BSM is used as BSM 0,14, where 0 indicates that the current mode is not saved (the program is leaving the subroutine, anyway), and a return to the caller at the address and mode specified in register 14 is to be taken. Refer to IBM publication MVS/Extended Architecture System Programming Library: 31-Bit Addressing, GC28-1158-1, for extensive examples of the use of BAS, BASR, BASSM and BSM, in particular, pp. 29–30.
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Published in Physical Review Letters 110, 230501 (2013), Cai et al. reported an experimental demonstration of the simplest meaningful instance of this algorithm, that is, solving 2\times 2 linear equations for various input vectors. The quantum circuit is optimized and compiled into a linear optical network with four photonic quantum bits (qubits) and four controlled logic gates, which is used to coherently implement every subroutine for this algorithm. For various input vectors, the quantum computer gives solutions for the linear equations with reasonably high precision, ranging from fidelities of 0.825 to 0.993.
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The Windows API has always exposed a large part of the underlying structure of the Windows systems to programmers. This had the advantage of giving them much flexibility and power over their applications, but also creates great responsibility in how applications handle various low-level, sometimes tedious, operations that are associated with a graphical user interface. For example, a beginning C programmer will often write the simple "hello world" as their first assignment. The working part of the program is only a single printf line within the main subroutine.
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Automatic restart of the cycle with a reduced timestep in case of iteration limit or temperature overflow effectively reduced code crashes. A new option provided automatic deactivation of a port region when it is closed from the cylinder and reactivation when it communicates with the cylinder. Extensions to the particle-based liquid wall film model made the model more complete and a split injection option was also added. A new subroutine monitors the liquid and gaseous fuel phases and energy balance data and emissions are monitored and printed.
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Usually, the PC is incremented after fetching an instruction, and holds the memory address of ("points to") the next instruction that would be executed. Processors usually fetch instructions sequentially from memory, but control transfer instructions change the sequence by placing a new value in the PC. These include branches (sometimes called jumps), subroutine calls, and returns. A transfer that is conditional on the truth of some assertion lets the computer follow a different sequence under different conditions. A branch provides that the next instruction is fetched from elsewhere in memory.
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This included the traditional 8-bit accumulator and various status flags, but also included another set of sixteen 16-bit wide general-purpose registers. In addition to providing temporary storage, the user could select any one of these to be the program counter (PC) using the `SEP Rn` instruction, where n was a 4-bit value selecting one of the registers. This could be used as a small call stack by storing multiple PC's for the return addresses (see Subroutine calls below). Similarly, pointers and indirect addressing use the X register (SEX Rn instruction).
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South # address number = 200 # suite/apartment number = #358 # city = St. Petersburg # state = FL # postal-code = 33701 # postal-code-add-on = 4313 # country = USA Finer granularity has overheads for data input and storage. This manifests itself in a higher number of objects and methods in the object-oriented programming paradigm or more subroutine calls for procedural programming and parallel computing environments. It does however offer benefits in flexibility of data processing in treating each data field in isolation if required. A performance problem caused by excessive granularity may not reveal itself until scalability becomes an issue.
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Wheeler was elected a fellow of the Royal Society in 1981, and received a Computer Pioneer Award in 1985 for his contributions to assembly language programming. In 1994 he was inducted as a Fellow of the Association for Computing Machinery. In 2003, he was named a Computer History Museum Fellow Award recipient "for his invention of the closed subroutine, and for his architectural contributions to ILLIAC, the Cambridge Ring, and computer testing." The Computer Laboratory at the University of Cambridge annually holds the "Wheeler Lecture", a series of distinguished lectures named after him.
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Other architectures (such as SPARC) have a register with the same purpose but another name (in this case, "output register 7" or o7). The usage of a link register (or a general-purpose register, as is done in some other instruction set architectures) allows for faster calls to leaf subroutines. When the subroutine is non-leaf, passing the return address in a register can still result in generation of more efficient code for thunks, e.g. for a function whose sole purpose is to call another function with arguments rearranged in some way.
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Westi consumed less memory than CICS, which was attractive in the highly memory- constrained computing environments of the 1970s, in which 256KB was considered a large amount of memory. Westi operated as an application's mainline program and, like IBM's soon to follow CICS, programmers wrote subroutines to read and write data to and from terminals and discs. This real time paradigm became known as transaction processing. This differed from Westi's primary competitor, DUCS, which reversed that model in that it was a subroutine package that read from and wrote to monitors.
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A related notion to reserved words are predefined functions, methods, subroutines, or variables, particularly library routines from the standard library. These are similar in that they are part of the basic language, and may be used for similar purposes. However, these differ in that the name of a predefined function, method, or subroutine is typically categorized as an identifier instead of a reserved word, and is not treated specially in the syntactic analysis. Further, reserved words may not be redefined by the programmer, but predefineds can often be overridden in some capacity.
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A channel command word (CCW) is an instruction to a specialized I/O channel processor which is, in fact, a finite state machine. It is used to initiate an I/O operation, such as "read", "write" or "sense", on a channel- attached device. On system architectures that implement channel I/O, typically all devices are connected by channels, and so all I/O requires the use of CCWs. CCWs are organized into channel programs by the operating system, and I/O subroutine, a utility program, or by standalone software (such as test and diagnostic programs).
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Agner Fog is known as a "CPU analyst" to tech websites covering x86 CPUs. He maintains a five-volume manual for optimizing code for x86 CPUs, with details on the instruction timing and other features of individual microarchitectures. He also maintains a Vector Class Library for SIMD math, an assembly subroutine library ("asmlib"), as well as many other utilities. Agner Fog has also written extensively on the behavior of Intel C++ Compiler and Intel MKL on non-Intel CPUs, coining the term "cripple AMD" to describe the bias.
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It is often convenient to allocate space for this use by simply moving the top of the stack by enough to provide the space. This is very fast when compared to dynamic memory allocation, which uses the heap space. Note that each separate activation of a subroutine gets its own separate space in the stack for locals. ; Parameter passing : Subroutines often require that values for parameters be supplied to them by the code which calls them, and it is not uncommon that space for these parameters may be laid out in the call stack.
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For some purposes, the stack frame of a subroutine and that of its caller can be considered to overlap, the overlap consisting of the area where the parameters are passed from the caller to the callee. In some environments, the caller pushes each argument onto the stack, thus extending its stack frame, then invokes the callee. In other environments, the caller has a preallocated area at the top of its stack frame to hold the arguments it supplies to other subroutines it calls. This area is sometimes termed the outgoing arguments area or callout area.
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When, during a mission, the mutant Nostromo becomes sheathed in a strange cocoon, he reveals himself to be the carrier when he "hatches" as a Phalanx. Doom sends some operatives to bring the boy to him, however, some of the operatives turn out to be Phalanx themselves and begin attacking the group. Nostromo is eventually delivered to Doom, who then activates the subroutine within Nostromo and, bidding Spider-Man to take him to safety, blows up his castle, while Twilight brings reinforcements of aboriginal Martians to destroy the Phalanx in orbit.
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In the comic book series Batman Beyond 2.0, Terry no longer uses the Batcave following an argument with Bruce. He now uses Dick Grayson's apartment as his base of operations. When Terry is seriously injured in a battle with Rewire, he wakes up in the Batcave where Bruce has treated his injuries and left information regarding Rewire himself. He arrived there due to a built in subroutine in the suit that if the user is seriously injured or falls unconscious, the suit becomes automated and returns the user to the Batcave.
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An object in OOP can be described as a semi-autonomous unit comprising both information and behaviour. Objects communicate by means of "method calls", which are essentially subroutine calls, done indirectly via the class to which the receiving object belongs. The object's internal data can only be accessed by means of method calls, so this is a form of information hiding or "encapsulation". Encapsulation, however, predates OOP - David Parnas wrote one of the seminal articles on it in the early 70s \- and is a basic concept in computing.
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Once the sequence is in packed form, Albers and Hagerup use a form of merge sort to sort it; when two sequences are being merged to form a single longer sequence, the same bitonic sorting subroutine can be used to repeatedly extract packed words consisting of the smallest remaining elements of the two sequences. This algorithm gains enough of a speedup from its packed representation to sort its input in linear time whenever it is possible for a single word to contain keys; that is, when for some constant .
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Otherwise, the statements are skipped and the execution sequence continues from the statement following them. Unconditional branching statements allow an execution sequence to be transferred to another part of a program. These include the jump (called goto in many languages), switch, and the subprogram, subroutine, or procedure call (which usually returns to the next statement after the call). Early in the development of high-level programming languages, the introduction of the block enabled the construction of programs in which a group of statements and declarations could be treated as if they were one statement.
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Observe that the problem FSAT introduced above can be solved using only polynomially many calls to a subroutine which decides the SAT problem: An algorithm can first ask whether the formula \varphi is satisfiable. After that the algorithm can fix variable x_1 to TRUE and ask again. If the resulting formula is still satisfiable the algorithm keeps x_1 fixed to TRUE and continues to fix x_2, otherwise it decides that x_1 has to be FALSE and continues. Thus, FSAT is solvable in polynomial time using an oracle deciding SAT.
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18–19 Many important restrictions of this type, like checking that identifiers are used in the appropriate context (e.g. not adding an integer to a function name), or that subroutine calls have the appropriate number and type of arguments, can be enforced by defining them as rules in a logic called a type system. Other forms of static analyses like data flow analysis may also be part of static semantics. Newer programming languages like Java and C# have definite assignment analysis, a form of data flow analysis, as part of their static semantics.
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In statistical genetics, Felsenstein's tree-pruning algorithm (or Felsenstein's tree-peeling algorithm), attributed to Joseph Felsenstein, is an algorithm for computing the likelihood of an evolutionary tree from nucleic acid sequence data. The algorithm is often used as a subroutine in a search for a maximum likelihood estimate for an evolutionary tree. Further, it can be used in a hypothesis test for whether evolutionary rates are constant (by using likelihood ratio tests). It can also be used to provide error estimates for the parameters describing an evolutionary tree.
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All variables are lexically scoped at the subroutine or module level, but unlike most structured languages, ICI allows the current scope to be adjusted (Tcl also allows this, for example). ICI is not object-based, many object programming features can be emulated in the language by using a data structure inheritance feature called super- structures. To support application development, ICI has C-like file I/O and system interface support, as well as a high-level event trigger facility. The language also has a modest standard library of built-in functions.
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Radio Shack offered simple graphics animation programs Micro Movie and Micro Marquee, and Micro Music. Radio Shack offered a number of programming utilities, including an advanced debugger, a subroutine package, and a cross reference builder. Probably the most popular utility package was Super Utility written by Kim Watt of Breeze Computing. Other utility software such as Stewart Software's Toolkit offered the first sorted directory, decoding or reset of passwords, and the ability to eliminate parts of TRSDOS that were not needed in order to free up floppy disk space.
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Looking strictly at the functionality and capacity, the more equal competitor would be the TI-57. It lacked a few of the HP-25's functions, but had some other advantages. One notable deficiency of the HP-25/25C was the lack of a subroutine capability, at a time when the TI-58 and even the earlier SR-56 had subroutines. Although 49 fully merged keycodes were roughly equivalent to the unmerged 100 steps of the SR-56; by the time the TI-58 arrived with 480 steps, subroutines, DSZ loops, etc.
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Flow graphs can be nested, which is the equivalent of a subroutine call (although there is no notion of passing parameters), and flow graphs can also be sequenced, which is the equivalent of sequential execution of two pieces of code.. Prime flow graphs are defined as flow graphs that cannot be decomposed via nesting or sequencing using a chosen pattern of subgraphs, for example the primitives of structured programming.. Theoretical research has been done on determining, for example, the proportion of prime flow graphs given a chosen set of graphs.
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Reprinted Copeland (2005). The ACE implemented subroutine calls, whereas the EDVAC did not, and what also set the ACE apart from the EDVAC was the use of Abbreviated Computer Instructions, an early form of programming language. Initially, it was planned that Tommy Flowers, the engineer at the Post Office Research Station at Dollis Hill in north London, who had been responsible for building the Colossus computers should build the ACE, but because of the secrecy around his wartime achievements and the pressure of post-war work, this was not possible.
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Much of the content of Zen of Assembly Language was updated in Zen of Code Optimization: The Ultimate Guide to Writing Software That Pushes PCs to the Limit (1994), along with new material. The presentation of stepwise program refinement empirically demonstrated how algorithm re-design could improve performance up to a factor of 100. Assembly language re-coding, on the other hand, may only improve performance by a factor of 10. Abrash also showed how elusive performance improvement can be, and improving performance in one subroutine can expose bottlenecks in other routines.
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In computer programming, autoloading is the capability of loading and linking portions of a program from mass storage automatically when needed, so that the programmer is not required to define or include those portions of the program explicitly. Many high-level programming languages include autoload capabilities, which sacrifice some run-time speed for ease of coding and speed of initial compilation/linking. Typical autoload systems intercept procedure calls to undefined subroutines. The autoloader searches through a path of directories in the computer's file system, to find a file containing source or object code that defines the subroutine.
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The autoloader then loads and links the file, and hands control back to the main program so that the subroutine gets executed as if it had already been defined and linked before the call. Many interactive and high-level languages operate in this way. For example, IDL includes a primitive path searcher, and Perl allows individual modules to determine how and whether autoloading should occur. The Unix shell may be said to consist almost entirely of an autoloader (program), as its main job is to search a path of directories to load and execute command files.
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The rise of 64-bit x86 processors brought with it a change to the subroutine calling convention that required the first argument to a function to be passed in a register instead of on the stack. This meant that an attacker could no longer set up a library function call with desired arguments just by manipulating the call stack via a buffer overrun exploit. Shared library developers also began to remove or restrict library functions that performed actions particularly useful to an attacker, such as system call wrappers. As a result, return-into-library attacks became much more difficult to mount successfully.
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Simple QIOs, such as read or write requests, are either serviced by the kernel itself or by device drivers. Certain more complicated requests, specifically those involving tape drives and file-level operations, were originally executed by an Ancillary Control Processor (ACP) (a special purpose task with its own address mapping). The Files-11 ODS-1 file system on RSX-11 was implemented by a subroutine library that communicated with a task named F11ACP using a special set of QIOs called the "ACP QIOs." The equivalent functionality for controlling magnetic tape devices was provided by a task named MTAACP.
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Languages with an explicit return statement create the possibility of multiple return statements in the same function. Whether or not that is a good thing is controversial. Strong adherents of structured programming make sure each function has a single entry and a single exit (SESE). It has thus been arguedC++ Notes: Function return Statement that one should eschew the use of the explicit return statement except at the textual end of a subroutine, considering that, when it is used to "return early", it may suffer from the same sort of problems that arise for the GOTO statement.
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A statement somewhat resembles a procedure call in a modern language in the sense that execution returns to the code following the statement at the end of the called code; however, it does not provide any mechanism for parameter passing or for returning a result value. If a subroutine is invoked using a simple statement like , then control returns at the end of the called procedure. However, is unusual in that it may be used to call a range spanning a sequence of several adjacent procedures. This is done with the construct: PROCEDURE so-and-so.
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The operations we are interested in are FindRoot(Node v), Cut(Node v), Link(Node v, Node w), and Path(Node v). Every operation is implemented using the Access(Node v) subroutine. When we access a vertex v, the preferred path of the represented tree is changed to a path from the root R of the represented tree to the node v. If a node on the access path previously had a preferred child u, and the path now goes to child w, the old preferred edge is deleted (changed to a path-parent pointer), and the new path now goes through w.
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In computer science, a null function (or null operator) is a subroutine that leaves the program state unchanged. When it is part of the instruction set of a processor, it is called a NOP or NOOP (No OPeration). Mathematically, a (computer) function f is null if and only if its execution leaves the program state s unchanged. That is, a null function is an identity function whose domain and codomain are both the state space S of the program, and for which: : f(s)=s for all elements s \in S. Less rigorous definitions may also be encountered.
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A user exit is a subroutine invoked by a software package for a predefined event in the execution of the package. Clients of the package can substitute their own subroutines in place of the default ones provided by the package vendor to provide customized functionality. The earliest use of this term involved operating systems to let customized code temporarily take control when a pre-designated event occurred.IBM term: OS/MFT, MVT A more typical use is replacing the user exits provided by a sort/merge package, whereby the user program provides its own subroutines for comparing records.
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Dr. Dobb's Journal, Volume 1, Number 1, 1976, p. 12. ; : If string matches the BASIC line, advance cursor over and execute the next IL instruction; if the test fails, execute the IL instruction at the label lbl ; : Execute the IL subroutine starting at ; save the IL address following the CALL on the control stack ; : Report a syntax error if after deleting leading blanks the cursor is not positioned to reach a carriage return ; : Test value at the top of the AE stack to be within ranqe. If not, report an error. If so, attempt to position cursor at that line.
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When Sun Microsystems first released Java in 1995, AWT widgets provided a thin level of abstraction over the underlying native user- interface. For example, creating an AWT check box would cause AWT directly to call the underlying native subroutine that created a check box. However, a check box on Microsoft Windows is not exactly the same as a check box on Mac OS or on the various types of Unix. Some application developers prefer this model because it provides a high degree of fidelity to the underlying native windowing toolkit and seamless integration with native applications.
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A preprocessor procedure is a subroutine executed by the preprocessor. The procedure is delimited by `%PROCEDURE` and `%END` statements and can contain only preprocessor statements, without the leading `%`. It is invoked as a function reference from open code, outside of any preprocessor procedure, or from another preprocessor procedure, and returns a `CHARACTER` or `FIXED` value. When the procedure is invoked from open code the arguments are passed by name, that is they are interpreted as character strings delimited by commas or a right parenthesis, all leading, trailing, or embedded blanks are significant and considered part of the argument.
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Calculator keyboard & display The HP-65 had a program memory for up to 100 instructions of 6 bits which included subroutine calls and conditional branching based on comparison of x and y registers. Some but not all commands entered as multiple keystrokes were stored in a single program memory cell. When displaying a program, the key codes were shown without line numbers. A program could be saved to mylar-based magnetically coated cards (71 mm × 9.5 mm), which were fed through the reader by a small electric motor through a worm gear and rubber roller at a speed of 6 cm/s.
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Additionally, these tables are usually implemented such that a REDUCE results in a CALL to a closed subroutine which is external to the state machine and which performs a function which is implied by the semantics of the grammar rule which is being REDUCEd. Therefore, the parser is partitioned into an invariant state machine part, and a variant semantics part. This fundamental distinction encourages the development of high-quality parsers which are exceptionally reliable. Given a specific stack state and lookahead symbol, there are precisely four possible actions, ERROR, SHIFT, REDUCE, and STOP (hereinafter referred to as configurations).
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A variable length Packed BCD numeric data type is also implemented, providing machine instructions that perform arithmetic directly on packed decimal data. On the IBM 1130 and 1800, packed BCD is supported in software by IBM's Commercial Subroutine Package. Today, BCD data is still heavily used in IBM processors and databases, such as IBM DB2, mainframes, and Power6. In these products, the BCD is usually zoned BCD (as in EBCDIC or ASCII), Packed BCD (two decimal digits per byte), or "pure" BCD encoding (one decimal digit stored as BCD in the low four bits of each byte).
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One can set code breakpoints, both for code in RAM (often using a special machine instruction) and in ROM/flash. Data breakpoints are often available, as is bulk data download to RAM. Most designs have "halt mode debugging", but some allow debuggers to access registers and data buses without needing to halt the core being debugged. Some toolchains can use ARM Embedded Trace Macrocell (ETM) modules, or equivalent implementations in other architectures to trigger debugger (or tracing) activity on complex hardware events, like a logic analyzer programmed to ignore the first seven accesses to a register from one particular subroutine.
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The primary user interface of the ISE is the Project Navigator, which includes the design hierarchy (Sources), a source code editor (Workplace), an output console (Transcript), and a processes tree (Processes).FPGA Prototyping By Verilog Examples, John Wiley & Sons, 20-Sep-2011 The Design hierarchy consists of design files (modules), whose dependencies are interpreted by the ISE and displayed as a tree structure. For single-chip designs there may be one main module, with other modules included by the main module, similar to the `main()` subroutine in C++ programs. Design constraints are specified in modules, which include pin configuration and mapping.
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In other contexts, particularly the Python language, "factory" itself is used, as in this article."30.8 Classes Are Objects: Generic Object Factories", Learning Python, by Mark Lutz, 4th edition, O'Reilly Media, Inc., More broadly, "factory" may be applied not just to an object that returns objects from some method call, but to a subroutine that returns objects, as in a factory function (even if functions are not objects) or factory method.Factory Method, WikiWikiWeb Because in many languages factories are invoked by calling a method, the general concept of a factory is often confused with the specific factory method pattern design pattern.
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For example: "A Turing machine can simulate any type of subroutine found in programming languages, including recursive procedures and any of the known parameter-passing mechanisms" (Hopcroft and Ullman p. 157). A large enough FSA can also model any real computer, disregarding IO. Thus, a statement about the limitations of Turing machines will also apply to real computers. # The difference lies only with the ability of a Turing machine to manipulate an unbounded amount of data. However, given a finite amount of time, a Turing machine (like a real machine) can only manipulate a finite amount of data.
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The language of VBScript is modeled on Visual Basic, and therefore can be reviewed using similar categories: procedures, control structures, constants, variables, user interaction, array handling, date/time functions, error handling, mathematical functions, objects, regular expressions, string manipulation, and so on. The following are some key points of introduction to the VBScript language by microsoft A "procedure" is the main construct in VBScript for separating code into smaller modules. VBScript distinguishes between a function, which can return a result in an assignment statement, and a subroutine, which cannot. Parameters are positional, and can be passed by value or by reference.
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GAL statements can be entered to the interpreter on the fly, or entire automation scenarios can be predefined, such as the logic to define unattended operations of a system, and can be compiled offline, using the compiler program GALCOMP. GAL implements comparison by IF statements, setting of variables, by the LET statement and subroutine calls. GAL allows the programmer to break into REXX, and Assembler where it is needed. The very high level nature of GAL is exemplified by the EMAIL statement, which enables the programmer to send an email alert when an event is detected that requires human intervention.
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When using bank switching some caution was required in order not to corrupt the handling of subroutine calls, interrupts, the machine stack, and so on. While the contents of memory temporarily switched out from the CPU was inaccessible to the processor, it could be used by other hardware, such as video display, DMA, I/O devices, etc. CP/M-80 3.0 released in 1983 and the Z80-based TRS-80s the Model 4 and Model II supported bank switching to allow use of more than the 64 KB of memory that the 8080 or Z80 processor could address.
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In computational complexity theory, a fine-grained reduction is a transformation from one computational problem to another, used to relate the difficulty of improving the time bounds for the two problems. Intuitively, it provides a method for solving one problem efficiently by using the solution to the other problem as a subroutine. If problem A can be solved in time a(n) and problem B can be solved in time b(n), then the existence of an (a,b)-reduction from problem A to problem B implies that any significant speedup for problem B would also lead to a speedup for problem A.
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The difference between calling another coroutine by means of "yielding" to it and simply calling another routine (which then, also, would return to the original point), is that the relationship between two coroutines which yield to each other is not that of caller-callee, but instead symmetric. Any subroutine can be translated to a coroutine which does not call yield. Here is a simple example of how coroutines can be useful. Suppose you have a consumer-producer relationship where one routine creates items and adds them to a queue and another removes items from the queue and uses them.
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MINPACK is a library of FORTRAN subroutines for the solving of systems of nonlinear equations, or the least squares minimization of the residual of a set of linear or nonlinear equations. MINPACK, along with other similar libraries such as LINPACK and EISPACK originated from the Mathematics and Computer Science Division Software (MCS) of Argonne National Laboratory Written by Jorge Moré, Burt Garbow, and Ken Hillstrom MINPACK is free and designed to be highly portable, robust and reliable. The quality of its implementation of Levenberg-Marquardt is attested by Dennis and Schnabel. Five algorithmic paths each include a core subroutine and a driver routine.
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Hard disks, in the IBM Dolphin line of sealed cartridges, were available but expensive and were generally used as file systems storing data and executable programs (thereby eliminating the need to rely on the paper tape reader for system boot-up). Most work was done in a macro assembly language, with a fairly powerful macro language facility allowing great flexibility in code configuration and generation. Static variable binding, like Fortran, was the norm and the use of arbitrary subroutine call patterns was rare. The machines were usually deployed for very fixed jobs with a rigidly planned set of software.
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Return-oriented programming (ROP) is a computer security exploit technique that allows an attacker to execute code in the presence of security defenses such as executable space protection and code signing. In this technique, an attacker gains control of the call stack to hijack program control flow and then executes carefully chosen machine instruction sequences that are already present in the machine's memory, called "gadgets". Each gadget typically ends in a return instruction and is located in a subroutine within the existing program and/or shared library code. Chained together, these gadgets allow an attacker to perform arbitrary operations on a machine employing defenses that thwart simpler attacks.
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If a language supports first-class continuations (as do Scheme and Standard ML of New Jersey), portions of the call stack may also escape. If a subroutine allocates an object and returns a pointer to it, the object can be accessed from undetermined places in the program the pointer has "escaped". Pointers can also escape if they are stored in global variables or other data structures that, in turn, escape the current procedure. Escape analysis determines all the places where a pointer can be stored and whether the lifetime of the pointer can be proven to be restricted only to the current procedure and/or thread.
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On the older Atari 2600, sprite multiplexing was not intentionally designed in, but programmers discovered they could reset the TIA graphics chip to draw additional sprites on the same scanline. The sprite multiplexing technique relies on the program being able to identify what part of the video screen is being drawn at the moment, or being triggered by the video hardware to run a subroutine at the crucial moment. The programmer must carefully consider the layout of the screen. If the video graphics hardware is not reprogrammed in time for the extra sprites to be displayed, they will not appear, or will be drawn incorrectly.
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Quantum computers are devices that harness quantum mechanics to perform computations in ways that classical computers cannot. For certain problems, quantum algorithms supply exponential speedups over their classical counterparts, the most famous example being Shor's factoring algorithm. Few such exponential speedups are known, and those that are (such as the use of quantum computers to simulate other quantum systems) have so far found limited use outside the domain of quantum mechanics. This algorithm provides an exponentially faster method of estimating features of the solution of a set of linear equations, which is a problem ubiquitous in science and engineering, both on its own and as a subroutine in more complex problems.
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Pages are used to define subroutines, which return when the next line is on a different page. For instance, if a subroutine for calculating the square root of a number is in page 3, one might have three lines of code 3.1, 3.2 and 3.3, and it would be called using The code would return to the statement after the Do when it reaches the next line on a different page, for instance, 4.1. There is no need for the equivalent of a at the end, although if an early return is required, accomplishes this. Every line must start with a command keyword following the line number.
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Multi-dimensional arrays are commonly used in numerical algorithms (mainly from applied linear algebra) to store matrices. The structure of the C array is well suited to this particular task. However, since arrays are passed merely as pointers, the bounds of the array must be known fixed values or else explicitly passed to any subroutine that requires them, and dynamically sized arrays of arrays cannot be accessed using double indexing. (A workaround for this is to allocate the array with an additional "row vector" of pointers to the columns.) C99 introduced "variable- length arrays" which address some, but not all, of the issues with ordinary C arrays.
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A set of statements is in turn generally structured as a block, which in addition to grouping, also defines a lexical scope. Interrupts and signals are low-level mechanisms that can alter the flow of control in a way similar to a subroutine, but usually occur as a response to some external stimulus or event (that can occur asynchronously), rather than execution of an in-line control flow statement. At the level of machine language or assembly language, control flow instructions usually work by altering the program counter. For some central processing units (CPUs), the only control flow instructions available are conditional or unconditional branch instructions, also termed jumps.
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Since these holistic problem models could be independently automated and solved due to this closure, they could be blended into higher wholes by nesting one inside of another, in the manner of subroutines. And users could regard them as if they were ordinary subroutines. Yet semantically, this mathematical blending was considerably more complex than the mechanics of subroutines, because an iterative solution engine was attached to each problem model by its calling operator template above it in the program hierarchy. In its numerical solution process, this engine would take control and would call the problem model subroutine iteratively, not returning to the calling template until its system problem was solved.
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Several efficient algorithms are known for constructing Voronoi diagrams, either directly (as the diagram itself) or indirectly by starting with a Delaunay triangulation and then obtaining its dual. Direct algorithms include Fortune's algorithm, an O(n log(n)) algorithm for generating a Voronoi diagram from a set of points in a plane. Bowyer–Watson algorithm, an O(n log(n)) to O(n2) algorithm for generating a Delaunay triangulation in any number of dimensions, can be used in an indirect algorithm for the Voronoi diagram. Lloyd's algorithm and its generalization via the Linde–Buzo–Gray algorithm (aka k-means clustering), use the construction of Voronoi diagrams as a subroutine.
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In computer science, the all nearest smaller values problem is the following task: for each position in a sequence of numbers, search among the previous positions for the last position that contains a smaller value. This problem can be solved efficiently both by parallel and non-parallel algorithms: , who first identified the procedure as a useful subroutine for other parallel programs, developed efficient algorithms to solve it in the Parallel Random Access Machine model; it may also be solved in linear time on a non-parallel computer using a stack-based algorithm. Later researchers have studied algorithms to solve it in other models of parallel computation.
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As explained below, "BR 14" was the essential function of the program, to simply return to the operating system. This portion of a program name was often mnemonic -- for example, IEBUPDTE was the dataset utility (IEB) that applied updates (UPDTE) to source code files, and IEHINITT was the system utility (IEH) that initialized (INIT) magnetic tape labels (T). As explained further in "Usage" below, the name "BR14" comes from the IBM assembler- language instruction "Branch (to the address in) Register 14", which by convention is used to "return from a subroutine". Most early users of OS/360 were familiar with IBM Assembler Language and would have recognized this at once.
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The CPU architecture featured three register sets. The Nest was a 16-deep pushdown stack of arithmetic registers, The SJNS (Subroutine Jump Nesting Store) was a similar stack of return addresses. The Q Store was a set of 16 index registers, each of 48 bits divided into Counter (C), Increment (I) and Modifier (M) parts of 16 bits each. Flags on a memory-reference instruction specified whether the address should be modified by the M part of a Q Store, and, if so, whether the C part should be decremented by 1 and the M part incremented by the contents of the I part.
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Some instruction set architectures, such as Intel x86 and IBM/360 and its successors, have a load effective address instruction. This performs a calculation of the effective operand address, but instead of acting on that memory location, it loads the address that would have been accessed into a register. This can be useful when passing the address of an array element to a subroutine. It may also be a slightly sneaky way of doing more calculations than normal in one instruction; for example, using such an instruction with the addressing mode "base+index+offset" (detailed below) allows one to add two registers and a constant together in one instruction.
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The RoboLogix instruction set contains 16 commands, which are usually written as a program on a line-by-line basis. These commands are used to instruct the robot to perform tasks such as moving to a specific location, picking up an object, executing a subroutine, waiting, etc. One of the more popular commands in the instruction set is the IF instruction, which compares numerical values located in two registers. If a register has a value that is greater than (>), less than (<), greater than/equal to (>=), less than/equal to (<=), equal to (=), or not equal to (<>) another register, it will execute the next line in the program if the condition is true.
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Some programming languages such as Ada, C++, Clojure, Common Lisp, Fortran 90, Python, Ruby, Tcl, and Windows PowerShell allow for a default argument to be explicitly or implicitly given in a subroutine's declaration. This allows the caller to omit that argument when calling the subroutine. If the default argument is explicitly given, then that value is used if it is not provided by the caller. If the default argument is implicit (sometimes by using a keyword such as Optional) then the language provides a well-known value (such as null, Empty, zero, an empty string, etc.) if a value is not provided by the caller.
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In order to calculate this measure, the original CFG is iteratively reduced by identifying subgraphs that have a single-entry and a single-exit point, which are then replaced by a single node. This reduction corresponds to what a human would do if they extracted a subroutine from the larger piece of code. (Nowadays such a process would fall under the umbrella term of refactoring.) McCabe's reduction method was later called condensation in some textbooks, because it was seen as a generalization of the condensation to components used in graph theory. If a program is structured, then McCabe's reduction/condensation process reduces it to a single CFG node.
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In most systems a stack frame has a field to contain the previous value of the frame pointer register, the value it had while the caller was executing. For example, the stack frame of `DrawLine` would have a memory location holding the frame pointer value that `DrawSquare` uses (not shown in the diagram above). The value is saved upon entry to the subroutine and restored upon return. Having such a field in a known location in the stack frame enables code to access each frame successively underneath the currently executing routine's frame, and also allows the routine to easily restore the frame pointer to the caller's frame, just before it returns.
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For each processor in the system, an image is created that combines Harmony with the single multitask program for that processor at link time, an exception being a case where the kernel is programmed into a ROM. Although the term did not appear in the original papers, Harmony was later referred to as a microkernel. A key in Harmony is its use of the term "task", which in Harmony is defined as the "unit of sequential and synchronous execution" and "the unit of resource ownership". It is likened to a subroutine, but one that must be explicitly created and which runs independently of the task that created it.
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Formally, resource management (preventing resource leaks) consists of ensuring that a resource is released if and only if it is successfully acquired. This general problem can be abstracted as "before, body, and after" code, which normally are executed in this order, with the condition that the after code is called if and only if the before code successfully completes, regardless of whether the body code executes successfully or not. This is also known as execute around or a code sandwich, and occurs in various other contexts, such as a temporary change of program state, or tracing entry and exit into a subroutine. However, resource management is the most commonly cited application.
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In computer software, in compiler theory, an intrinsic function (or builtin function) is a function (subroutine) available for use in a given programming language whose implementation is handled specially by the compiler. Typically, it may substitute a sequence of automatically generated instructions for the original function call, similar to an inline function. Unlike an inline function, the compiler has an intimate knowledge of an intrinsic function and can thus better integrate and optimize it for a given situation. Compilers that implement intrinsic functions generally enable them only when a program requests optimization, otherwise falling back to a default implementation provided by the language runtime system (environment).
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The trace is zero if and only if the graph is triangle-free. For dense graphs, it is more efficient to use this simple algorithm which relies on matrix multiplication, since it gets the time complexity down to O(n2.373), where n is the number of vertices. As showed, triangle-free graph recognition is equivalent in complexity to median graph recognition; however, the current best algorithms for median graph recognition use triangle detection as a subroutine rather than vice versa. The decision tree complexity or query complexity of the problem, where the queries are to an oracle which stores the adjacency matrix of a graph, is Θ(n2).
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Entrance into that scope typically begins a variable's lifetime (as it comes into context) and exit from that scope typically ends its lifetime (as it goes out of context). For instance, a variable with "lexical scope" is meaningful only within a certain function/subroutine, or more finely within a block of expressions/statements (accordingly with function scope or block scope); this is static resolution, performable at parse-time or compile-time. Alternatively, a variable with dynamic scope is resolved at run-time, based on a global binding stack that depends on the specific control flow. Variables only accessible within a certain functions are termed "local variables".
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Thus a virtual instrument can be run as either a program, with the front panel serving as a user interface, or, when dropped as a node onto the block diagram, the front panel defines the inputs and outputs for the node through the connector pane. This implies each VI can be easily tested before being embedded as a subroutine into a larger program. The graphical approach also allows nonprogrammers to build programs by dragging and dropping virtual representations of lab equipment with which they are already familiar. The LabVIEW programming environment, with the included examples and documentation, makes it simple to create small applications.
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Dijkstra's algorithm, conceived by Dutch computer scientist Edsger Dijkstra in 1956 and published in 1959, is a graph search algorithm that solves the single-source shortest path problem for a graph with non-negative edge path costs, producing a shortest path tree. Dijkstra's algorithm is so powerful that it not only finds the shortest path from a chosen source to a given destination, it finds all of the shortest paths from the source to all destinations. This algorithm is often used in routing and as a subroutine in other graph algorithms. Dijkstra's algorithm is considered as one of the most popular algorithms in computer science.
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All input/output requests, whether by the MTS job program itself or by a program running under MTS, is done using a common set of subroutine calls (GETFD, FREEFD, READ, WRITE, CONTROL, GDINFO, ATTNTRP, ...). The same subroutines are used no matter what program is doing the I/O and no matter what type of file or device is being used (typewriter or graphics terminal, line printer, card punch, disk file, magnetic and paper tape, etc.). No knowledge of the format or contents of system control blocks is required to use these subroutines. Programs may use specific characteristics of a particular device, but such programs will be somewhat less device independent.
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HyperTalk was a high-level, procedural programming language created in 1987 by Dan Winkler and used in conjunction with Apple Computer's HyperCard hypermedia program by Bill Atkinson. Because the main target audience of HyperTalk was beginning programmers, HyperTalk programmers were usually called "authors" and the process of writing programs was known as "scripting". HyperTalk scripts resembled written English and used a logical structure similar to that of the Pascal programming language. HyperTalk supported the basic control structures of procedural languages: repeat for/while/until, if/then/else, as well as function and message "handler" calls (a function handler was a subroutine and a message handler a procedure).
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In many instructions of the instruction set, data could be optionally masked and/or rotated. Single instructions existed for such esoteric functions as "find first set bit (the rightmost bit that is set) in a data word, optionally reset the bit and tell me the position of the bit". Having this function as an atomic instruction (rather than implementing as a subroutine) dramatically sped scanning for service requests or idle circuits. The central processor was implemented as a hierarchical state machine. Memory card for 64 words of 44 bits Memory had a 44-bit word length for program stores, of which six bits were for Hamming error correction and one was used for an additional parity check.
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SVC is a two byte instruction with the operation code of 0A0x; the second byte, the SVC number, indicates the specific request. SVC invokes a supervisory function--usually implemented as a "closed subroutine" of the system's SVC interrupt handler. Information passed to and from the SVC routines is passed in general purpose registers or in memory. Under IBM- developed operating systems, return from an SVC routine is, for type 2, 3 and 4 SVC routines, via an SVC 3 (EXIT) invocation, and for other SVC types by the privileged Load PSW (LPSW) instruction, and which is executed on behalf of the SVC routine by the control program's dispatcher or SVC interrupt handler.
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PSGI or Perl Web Server Gateway Interface is an interface between web servers and web applications and frameworks written in the Perl programming language that allows writing portable applications that can be run as standalone servers or using CGI, FastCGI, mod_perl, et al. It is inspired by the Web Server Gateway Interface for Python, Rack for Ruby and JSGI for JavaScript. A PSGI application is a Perl subroutine that accepts arguments as a single hash reference and returns a reference to an array of three elements: an HTTP status code, a reference to an array of HTTP headers and a reference to an array of HTTP body lines (usually a generated HTML document) or a filehandle-like object.
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In computer programming, a nested function (or nested procedure or subroutine) is a function which is defined within another function, the enclosing function. Due to simple recursive scope rules, a nested function is itself invisible outside of its immediately enclosing function, but can see (access) all local objects (data, functions, types, etc.) of its immediately enclosing function as well as of any function(s) which, in turn, encloses that function. The nesting is theoretically possible to unlimited depth, although only a few levels are normally used in practical programs. Nested functions are used in many approaches to structured programming, including early ones, such as ALGOL, Simula 67 and Pascal, and also in many modern dynamic languages and functional languages.
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In the context of games for many 8-bit computers, users could load games into memory and, before launching them, modify specific memory addresses in order to cheat, getting an unlimited number of lives, immunity, invisibility, etc. Such modifications were performed using POKE statements. The Commodore 64, ZX Spectrum and Amstrad CPC also allowed players with the relevant cartridges or Multiface add-on to freeze the running program, enter POKEs, and resume. For example, in Knight Lore for the ZX Spectrum, immunity can be achieved with the following command: POKE 47196, 201 In this case, the value 201 corresponds to a RET instruction, so that the game returns from a subroutine early before triggering collision detection.
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Only eight bytes of that range are used at any given time, determined by the two bank select bits in the PSW. The following is a partial list of the 8051's registers, which are memory-mapped into the special function register space: ; Stack pointer, SP (0x81): This is an 8-bit register used by subroutine call and return instructions. The stack grows upward; the SP is incremented before pushing, and decremented after popping a value. ; Data pointer, DP (0x82–83): This is a 16-bit register that is used for accessing PMEM and XRAM. ; Program status word, PSW (0xD0): This contains important status flags, by bit number: ; Accumulator, A (0xE0): This register is used by most instructions.
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FindRoot refers to finding the root of the represented tree that contains the node v. Since the access subroutine puts v on the preferred path, we first execute an access. Now the node v is on the same preferred path, and thus the same auxiliary tree as the root R. Since the auxiliary trees are keyed by depth, the root R will be the leftmost node of the auxiliary tree. So we simply choose the left child of v recursively until we can go no further, and this node is the root R. The root may be linearly deep (which is worst case for a splay tree), we therefore splay it so that the next access will be quick.
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Nostromo then reveals himself to be the Phalanx Scout, while Winn is also revealed to be a Phalanx agent. Winn takes Nostromo to Latveria to uplink with the collective while the others return to the surface and battle a Phalanx Dread Node, as it attempts to assimilate the Savage Land. Nostromo is linked with the Phalanx, however the intervention of Doom, who had known about the scout program since the Phalanx invasion of the 20th century, activated a hidden subroutine in his programming that broke him free of the collective. As he escaped with Spider-Man and Xina Kwan, Doom sacrificed himself to destroy the rest of the Phalanx presence on Earth.
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Raku rules are the regular expression, string matching and general-purpose parsing facility of the Raku programming language, and are a core part of the language. Since Perl's pattern-matching constructs have exceeded the capabilities of formal regular expressions for some time, Raku documentation refers to them exclusively as regexes, distancing the term from the formal definition. Raku provides a superset of Perl 5 features with respect to regexes, folding them into a larger framework called rules, which provide the capabilities of a parsing expression grammar, as well as acting as a closure with respect to their lexical scope. Rules are introduced with the `rule` keyword, which has a usage quite similar to subroutine definitions.
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When a subroutine is ready to return, it executes an epilogue that undoes the steps of the prologue. This will typically restore saved register values (such as the frame pointer value) from the stack frame, pop the entire stack frame off the stack by changing the stack pointer value, and finally branch to the instruction at the return address. Under many calling conventions the items popped off the stack by the epilogue include the original argument values, in which case there usually are no further stack manipulations that need to be done by the caller. With some calling conventions, however, it is the caller's responsibility to remove the arguments from the stack after the return.
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It remains to empty the other input list. while A is not empty do append head(A) to C drop the head of A while B is not empty do append head(B) to C drop the head of B return C When the inputs are linked lists, this algorithm can be implemented to use only a constant amount of working space; the pointers in the lists' nodes can be reused for bookkeeping and for constructing the final merged list. In the merge sort algorithm, this subroutine is typically used to merge two sub-arrays , of a single array . This can be done by copying the sub-arrays into a temporary array, then applying the merge algorithm above.
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If the input is given as a subroutine for calculating , the cycle detection problem may be trivially solved using only function applications, simply by computing the sequence of values and using a data structure such as a hash table to store these values and test whether each subsequent value has already been stored. However, the space complexity of this algorithm is proportional to , unnecessarily large. Additionally, to implement this method as a pointer algorithm would require applying the equality test to each pair of values, resulting in quadratic time overall. Thus, research in this area has concentrated on two goals: using less space than this naive algorithm, and finding pointer algorithms that use fewer equality tests.
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A third area to note is the adoption of VBScript as the internal scripting language for some embedded applications, such as industrial operator interfaces and human machine interfaces. The hierarchical DBMS InterSystems Caché (which has its roots in the language MUMPS) also supports an implementation of VBScript, Cache BASIC, for programming stored code. VBScript omits several useful features of the full Visual Basic, such as strong typing, extended error trapping and the ability to pass a variable number of parameters to a subroutine. However, its use is relatively widespread because it is easy to learn and because those who implement code in the language need not pay royalties to Microsoft as long as the VBScript trade mark is acknowledged.
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As an important special case, which is used as a subroutine in the general algorithm (see below), the Pohlig–Hellman algorithm applies to groups whose order is a prime power. The basic idea of this algorithm is to iteratively compute the p-adic digits of the logarithm by repeatedly "shifting out" all but one unknown digit in the exponent, and computing that digit by elementary methods. (Note that for readability, the algorithm is stated for cyclic groups — in general, G must be replaced by the subgroup \langle g\rangle generated by g, which is always cyclic.) :Input. A cyclic group G of order n=p^e with generator g and an element h\in G. :Output.
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In situations where a coroutine would be the natural implementation of a mechanism, but is not available, the typical response is to use a closurea subroutine with state variables (static variables, often boolean flags) to maintain an internal state between calls, and to transfer control to the correct point. Conditionals within the code result in the execution of different code paths on successive calls, based on the values of the state variables. Another typical response is to implement an explicit state machine in the form of a large and complex switch statement or via a goto statement, particularly a computed goto. Such implementations are considered difficult to understand and maintain, and a motivation for coroutine support.
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Programming features included a real-time clock, programmable timers and subroutine calls with parameter passing and recursion. It was also HP's first calculator based on the Saturn processor, later versions of which are found in the popular HP-48 series calculators and most more recent HP calculator models. Since the hand- pulled magnetic cards (HP-75 compatible) could only store two tracks of 650 bytes each, the card reader (installed under the logo plate above the numeric keyboard) was not a very popular option. Larger storage capacities could be accommodated through HP-IL peripherals such as the 82161A cassette drive or 9114A diskette drive that were also battery-powered and portable, if rather bulky compared to the 71B.
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The selected element is removed from all the lists where it appears as a head and appended to the output list. The process of selecting and removing a good head to extend the output list is repeated until all remaining lists are exhausted. If at some point no good head can be selected, because the heads of all remaining lists appear in any one tail of the lists, then the merge is impossible to compute due to inconsistent orderings of dependencies in the inheritance hierarchy and no linearization of the original class exists. A naive divide and conquer approach to computing the linearization of a class may invoke the algorithm recursively to find the linearizations of parent classes for the merge-subroutine.
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Both of these problems are in P, yet the runtime of the second grows considerably faster than the runtime of the first as the input size increases. One might ask whether it would be better to define the class of "efficiently solvable" problems using some smaller polynomial bound, like n^2, rather than all polynomials, which allows for such large discrepancies. It turns out, however, that the polynomials are the smallest class of functions containing the linear functions that are closed under addition, multiplication, and composition. This means that the polynomials are the smallest class that enables the composition of "efficient algorithms"; that is, a polynomial-time algorithm that calls a polynomial-time subroutine still yields a polynomial-time algorithm.
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Most programming languages include the concept of a subroutine or function, a mechanism that allows commonly used code to be encapsulated and re-used throughout a program. For instance, a program that makes heavy use of mathematics might need to perform the square root calculation on various numbers throughout the program, so this code might be isolated in a `sqrt(aNumber)` function that is "passed in" the number to perform the square root calculation on, and "returns" the result. In many cases the code in question already exists, either implemented in hardware or as part of the underlying operating system the program runs within. In these cases the `sqrt` function can be further simplified by calling the built-in code.
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During the 1980s, IBM at Hursley Park produced a version of CICS that supported what became known as "Command-level CICS" which still supported the older programs but introduced a new API style to application programs. A typical Command-level call might look like the following: EXEC CICS SEND MAPSET('LOSMATT') MAP('LOSATT') END-EXEC The values given in the SEND MAPSET command correspond to the names used on the first DFHMSD macro in the map definition given below for the MAPSET argument, and the DFHMSI macro for the MAP argument. This is pre-processed by a pre- compile batch translation stage, which converts the embedded commands (EXECs) into call statements to a stub subroutine. So, preparing application programs for later execution still required two stages.
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Generally if there are only a few small parameters, processor registers will be used to pass the values, but if there are more parameters than can be handled this way, memory space will be needed. The call stack works well as a place for these parameters, especially since each call to a subroutine, which will have differing values for parameters, will be given separate space on the call stack for those values. ; Evaluation stack : Operands for arithmetic or logical operations are most often placed into registers and operated on there. However, in some situations the operands may be stacked up to an arbitrary depth, which means something more than registers must be used (this is the case of register spilling).
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Intuitively, problem A is reducible to problem B if an algorithm for solving problem B efficiently (if it existed) could also be used as a subroutine to solve problem A efficiently. When this is true, solving A cannot be harder than solving B. "Harder" means having a higher estimate of the required computational resources in a given context (e.g., higher time complexity, greater memory requirement, expensive need for extra hardware processor cores for a parallel solution compared to a single-threaded solution, etc.). The existence of a reduction from A to B can be written in the shorthand notation A ≤m B, usually with a subscript on the ≤ to indicate the type of reduction being used (m : mapping reduction, p : polynomial reduction).
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In computer programming, housekeeping can refer to either a standard entry or exit routine appended to a user-written block of code (such as a subroutine or function, sometimes known as a function prologue and epilogue) at its entry and exit or, alternatively, to any other automated or manual software process whereby a computer is cleaned up after usage (e.g. freeing resources such as virtual memory). This might include such activities as removing or archiving logs that the system has made as a result of the users activities, or deletion of temporary files which may otherwise simply take up space. Housekeeping can be described as a necessary chore, required to perform a particular computer's normal activity but not necessarily part of the algorithm.
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In versions of Windows that did not use the Windows NT kernel (as well as DOS and some other operating systems), programs could access the parallel port with simple outportb() and inportb() subroutine commands. In operating systems such as Windows NT and Unix (NetBSD, FreeBSD, Solaris, 386BSD, etc.), the microprocessor is operated in a different security ring, and access to the parallel port is prohibited, unless using the required driver. This improves security and arbitration of device contention. On Linux, inb() and outb() can be used when a process is run as root and an ioperm() command is used to allow access to its base address; alternatively, ppdev allows shared access and can be used from userspace if the appropriate permissions are set.
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By using this divide and conquer approach we can achieve the same level of complexity for the overall matrix. (In principle, one could continue dividing the matrices until a base case of size 1×1 is reached, but in practice one uses a larger base case (e.g. 16×16) in order to amortize the overhead of the recursive subroutine calls.) Most cache-oblivious algorithms rely on a divide-and-conquer approach. They reduce the problem, so that it eventually fits in cache no matter how small the cache is, and end the recursion at some small size determined by the function-call overhead and similar cache-unrelated optimizations, and then use some cache- efficient access pattern to merge the results of these small, solved problems.
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A weighted matroid is a matroid together with a function from its elements to the nonnegative real numbers. The weight of a subset of elements is defined to be the sum of the weights of the elements in the subset. The greedy algorithm can be used to find a maximum-weight basis of the matroid, by starting from the empty set and repeatedly adding one element at a time, at each step choosing a maximum- weight element among the elements whose addition would preserve the independence of the augmented set. This algorithm does not need to know anything about the details of the matroid's definition, as long as it has access to the matroid through an independence oracle, a subroutine for testing whether a set is independent.
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Whenever any two points are too far apart from each other for both to belong to the same cluster, a clause is added to the instance that prevents this assignment. The same method also can be used as a subroutine when the individual cluster diameters are unknown. To test whether a given sum of diameters can be achieved without knowing the individual cluster diameters, one may try all maximal pairs of target diameters that add up to at most the given sum, representing each pair of diameters as a 2-satisfiability instance and using a 2-satisfiability algorithm to determine whether that pair can be realized by a clustering. To find the optimal sum of diameters one may perform a binary search in which each step is a feasibility test of this type.
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Here is an example of recursive subroutine in C/C++ to find Fibonacci numbers: int Fib(int n) { if (n <= 1) { return n; } return Fib(n - 1) + Fib(n - 2); } Early languages like Fortran did not initially support recursion because variables were statically allocated, as well as the location for the return address. Most computers before the late 1960s such as the PDP-8 did not have support for hardware stack registers. Modern languages after ALGOL such as PL/I and C almost invariably use a stack, usually supported by most modern computer instruction sets to provide a fresh activation record for every execution of a subprogram. That way, the nested execution is free to modify its local variables without concern for the effect on other suspended executions in progress.
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In comparison, a Linux system in 2007 might have occupied 18 MB. The first MIT GE-645 had 512 kilowords of memory (2 MiB), a truly enormous amount at the time, and the kernel used only a moderate portion of Multics main memory. The entire system, including the operating system and the complex PL/1 compiler, user commands, and subroutine libraries, consisted of about 1500 source modules. These averaged roughly 200 lines of source code each, and compiled to produce a total of roughly 4.5 MiB of procedure code, which was fairly large by the standards of the day. Multics compilers generally optimised more for code density than CPU performance, for example using small sub-routines called operators for short standard code sequences, which makes comparison of object code size with modern systems less useful.
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In an algorithm of this sort (as for divide and conquer algorithms in generalRadu Rugina and Martin Rinard, "Recursion unrolling for divide and conquer programs," in Languages and Compilers for Parallel Computing, chapter 3, pp. 34–48. Lecture Notes in Computer Science vol. 2017 (Berlin: Springer, 2001).), it is desirable to use a larger base case in order to amortize the overhead of the recursion. If N = 1, then there is roughly one recursive subroutine call for every input, but more generally there is one recursive call for (roughly) every N/2 inputs if the recursion stops at exactly n = N. By making N sufficiently large, the overhead of recursion can be made negligible (precisely this technique of a large base case for recursive summation is employed by high-performance FFT implementations).
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Implementation issues can also have an effect on efficiency, such as the choice of programming language, or the way in which the algorithm is actually coded, or the choice of a compiler for a particular language, or the compilation options used, or even the operating system being used. In many cases a language implemented by an interpreter may be much slower than a language implemented by a compiler. See the articles on just-in-time compilation and interpreted languages. There are other factors which may affect time or space issues, but which may be outside of a programmer's control; these include data alignment, data granularity, cache locality, cache coherency, garbage collection, instruction-level parallelism, multi-threading (at either a hardware or software level), simultaneous multitasking, and subroutine calls.
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A compression virus is an example of a benevolent computer virus, invented by Fred Cohen. It searches for an uninfected executable file, compresses the file and prepends itself to it. The virus can be described in pseudo code1984, Computer Viruses - Theory and Experiments program compression-virus:= {01234567; subroutine infect-executable:= {loop:file = get-random-executable-file; if first-line-of-file = 01234567 then goto loop; compress file; prepend compression-virus to file; } main-program:= {if ask-permission then infect-executable; uncompress the-rest-of-this-file into tmpfile; run tmpfile;} } The 01234567 is the virus signature, and is used to make sure (if first-line- of-file = 01234567) the file is not already infected. The virus then asks for permission (ask-permission) to infect a random executable (get-random- executable-file).
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Because of the 16-bit address bus, and the 8-bit data bus, the sixteen general purpose registers are 16 bits wide, but the accumulator D-register is only 8 bits wide. The accumulator, therefore, tends to be a bottleneck. Transferring the contents of one register to another involves four instructions (one Get and one Put on the HI byte of the register, and a similar pair for the LO byte: GHI R1; PHI R2; GLO R1; PLO R2). Similarly, loading a new constant into a register (such as a new address for a subroutine jump, or the address of a data variable) also involves four instructions (two load immediate, LDI, instructions, one for each half of the constant, each one followed by a Put instruction to the register, PHI and PLO).
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Thus code executing with the virtual PC set to 0xE200000, for example, would automatically be in ring 7, and calling a subroutine in a different section of memory would automatically cause a ring transfer. The hardware severely restricts the ways in which control can be passed from one ring to another, and also enforces restrictions on the types of memory access that can be performed across rings. Using x86 as an example, there is a special gate structure which is referenced by the call instruction that transfers control in a secure way towards predefined entry points in lower-level (more trusted) rings; this functions as a supervisor call in many operating systems that use the ring architecture. The hardware restrictions are designed to limit opportunities for accidental or malicious breaches of security.
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Each program or subroutine could have up to 10 local labels called LBL0 .. LBL9 for jumps and branches. The FX-501P and FX-502P supported indirect addressing both for memory access and jumps and therefore the programming model could be considered Turing complete. Since the FX-501P and FX-502P only employed a seven-segment display each program step was represented by a special 2-digit codes made up of the digits 0 .. 9 and the character C, E, F and P. The calculator came with a special overlaycasio fx-501p with programming overlay so the user did not need to memorize the mapping between code and actual command. What differentiated the FX-501 / FX-502P from its competitors was that programming was retained in a battery- buffered memory when the calculator was turned off.
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In total instruction path length only, a program coded in an imperative style, using no subroutines, would have the lowest count. However, the binary size of such a program may be larger than the same program coded using subroutines (as in functional and procedural programming) and would reference more non-local physical instructions that may increase cache misses and instruction fetch overhead in modern processors. The paradigms that use subroutines extensively (including functional, procedural, and object-oriented) and do not also use significant inline expansion (inlining, via compiler optimizations) will, consequently, use a larger fraction of total resources on the subroutine linkages. Object-oriented programs that do not deliberately alter program state directly, instead using mutator methods (or setters) to encapsulate these state changes, will, as a direct consequence, have more overhead.
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The data sent over the bus was examined by the Z80 on the card, which then ran a selected subroutine contained in its ROM to place data into the frame buffer. The screen buffer could be moved to or from the computer's main memory - useful for printing when pushed from the card to the computer, or displaying bitmap graphics when reversed. The 4 kB ROM normally contained "Screenware Pak I", which provided routines to emulate an 85 by 40 line character screen, which also allowed the user to define their own 12 by 6 pixel character sets in the card's RAM. The optional 6 kB "Screenware Pak II" (in 8 kV of ROM) was a superset of Pak I, adding circle, line and polygon drawing routines, flood fill and a variety of other features.
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At any step, it may perform one of three actions: it may copy any pointer it has to another object in memory, it may apply and replace any of its pointers by a pointer to the next object in the sequence, or it may apply a subroutine for determining whether two of its pointers represent equal values in the sequence. The equality test action may involve some nontrivial computation: for instance, in Pollard's rho algorithm, it is implemented by testing whether the difference between two stored values has a nontrivial greatest common divisor with the number to be factored. In this context, by analogy to the pointer machine model of computation, an algorithm that only uses pointer copying, advancement within the sequence, and equality tests may be called a pointer algorithm.
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Using coroutines for state machines or concurrency is similar to using mutual recursion with tail calls, as in both cases the control changes to a different one of a set of routines. However, coroutines are more flexible and generally more efficient. Since coroutines yield rather than return, and then resume execution rather than restarting from the beginning, they are able to hold state, both variables (as in a closure) and execution point, and yields are not limited to being in tail position; mutually recursive subroutines must either use shared variables or pass state as parameters. Further, each mutually recursive call of a subroutine requires a new stack frame (unless tail call elimination is implemented), while passing control between coroutines uses the existing contexts and can be implemented simply by a jump.
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Selection algorithms still have the downside of requiring memory, that is, they need to have the full sample (or a linear- sized portion of it) in memory. Because this, as well as the linear time requirement, can be prohibitive, several estimation procedures for the median have been developed. A simple one is the median of three rule, which estimates the median as the median of a three-element subsample; this is commonly used as a subroutine in the quicksort sorting algorithm, which uses an estimate of its input's median. A more robust estimator is Tukey's ninther, which is the median of three rule applied with limited recursion: if is the sample laid out as an array, and :, then : The remedian is an estimator for the median that requires linear time but sub-linear memory, operating in a single pass over the sample.
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The first version, VP1, was the basis of its parallel processing multimedia OS and platform, TAOS. VP1 supported a RISC-like instruction set with 16 32-bit registers, and had data types of 32- and 64-bit integers and 32- and 64-bit IEEE floating point numbers in registers, and also supported 8- and 16-bit integers in memory. The second version, VP2, was released in 1998 as the basis of a new version of the portable multimedia platform, first known as Elate and then as intent. VP2 supported the same data types and data processing operations as VP1, but had additional features for better support of high level languages such as demarcation of subroutines, by-value parameters, and a very large theoretical maximum number of registers local to the subroutine for use as local variables.
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In the most general case, the input to counting sort consists of a collection of items, each of which has a non-negative integer key whose maximum value is at most . In some descriptions of counting sort, the input to be sorted is assumed to be more simply a sequence of integers itself, but this simplification does not accommodate many applications of counting sort. For instance, when used as a subroutine in radix sort, the keys for each call to counting sort are individual digits of larger item keys; it would not suffice to return only a sorted list of the key digits, separated from the items. In applications such as in radix sort, a bound on the maximum key value will be known in advance, and can be assumed to be part of the input to the algorithm.
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This article will use the term "module" to refer to any name or equivalent symbol, which is used to provide an identifier for a piece of code or data external to the scope to which it is referenced. A module may refer to a subroutine, a function, Fortran Common or Block Data, an object or class, a method or property of an object or class, or any other named routine or identifier external to that particular scope referencing the external name. The terms "assembler" for a program that converts assembly language to machine code, as well as as the process of using one, and as the process of using a "compiler," which does the same thing for high-level languages, should, for the purposes of this article. be considered interchangeable; thus where "compile" and "compiler" are used, substitute "assemble" and "assembler" as needed.
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An algorithm for listing all maximal independent sets or maximal cliques in a graph can be used as a subroutine for solving many NP- complete graph problems. Most obviously, the solutions to the maximum independent set problem, the maximum clique problem, and the minimum independent dominating problem must all be maximal independent sets or maximal cliques, and can be found by an algorithm that lists all maximal independent sets or maximal cliques and retains the ones with the largest or smallest size. Similarly, the minimum vertex cover can be found as the complement of one of the maximal independent sets. observed that listing maximal independent sets can also be used to find 3-colorings of graphs: a graph can be 3-colored if and only if the complement of one of its maximal independent sets is bipartite.
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Land after reconstruction, commissioned in 2014 A new stage in the history of the road came with the adoption of the Russian Federation Government of the Federal Target Program (FTP) "Development of Transport System of Russia (2010-2015)". As part of the execution of the subroutine "Highways" set the task of bringing 85% of the road length Never-Yakutsk in 2018 up to standard, and by 2022 to complete the reconstruction of the entire road to Magadan. Thus, by 2022 over its entire length of the highway should have a major type of asphalt concrete coatings. Currently it has successfully implemented sections of the federal target program for the reconstruction of the road, which is part of the international transport corridor linking the Auto-advance on the border of the Russian Federation and the People's Republic of China to the sea port in the city of Magadan.
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The unrotated line has the endpoint (1, 0), which points to the right. Mirroring is available in two forms: `MX` to mirror in x and `MY` to mirror in y. Mirroring is a bit confusing, because `MX` causes a negation of the x coordinate, which effectively mirrors about the y axis. FIGURE B.4 The transformations of a CIF "call": (a) Subroutine 10: BOX 100 200 50 50; WIRE 10 50 50 100 150; (b) Invocation: C 10 T -50 0 MX MY; (c) Invocation: C 10 R 0 -1 MX; (d) Invocation: C 10 MX R 0 -1; Any number of transformations can be applied to an object and their listed order is the sequence that will be used to apply them. Figure B.4 shows some examples, illustrating the importance of ordering the transformations (notice that Figs. B.4c and B.4d produce different results by rearranging the transformations).
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These do not have analogous language- level concepts for variables: variable lifetime ends implicitly (for automatic variables, on stack unwind; for static variables, on program termination), and at this time (or later, depending on implementation) memory is deallocated, but no finalization is done in general. However, when an object's lifetime is tied to a variable's lifetime, the end of the variable's lifetime causes finalization of the object; this is a standard paradigm in C++. Together these yield four implementation-level steps: :allocation, initialization, finalization, deallocation These steps may be done automatically by the language runtime, interpreter, or virtual machine, or may be manually specified by the programmer in a subroutine, concretely via methods – the frequency of this varies significantly between steps and languages. Initialization is very commonly programmer-specified in class-based languages, while in strict prototype-based languages initialization is automatically done by copying.
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The main difficulty in designing an envy-free procedure for n > 2 agents is that the problem is not "divisible". I.e., if we divide half of the cake among n/2 agents in an envy-free manner, we cannot just let the other n/2 agents divide the other half in the same manner, because this might cause the first group of n/2 agents to be envious (e.g., it is possible that A and B both believe they got 1/2 of their half which is 1/4 of the entire cake; C and D also believe the same way; but, A believes that C actually got the entire half while D got nothing, so A envies C). The Robertson–Webb protocol addresses this difficulty by requiring that the division is not only envy-free but also near-exact. The recursive part of the protocol is the following subroutine.
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Subsequently, this made it possible for OpenSSH to avoid any dependency on OpenSSL, via a compile-time option. ChaCha20 is also used for the `arc4random` random number generator in FreeBSD, OpenBSD, and NetBSD operating systems, instead of the broken RC4, and in DragonFly BSD for the CSPRNG subroutine of the kernel. Starting from version 4.8, the Linux kernel uses the ChaCha20 algorithm to generate data for the nonblocking /dev/urandom device. An implementation reference for ChaCha20 has been published in . The IETF's implementation modified Bernstein's published algorithm by changing 64-bit nonce and 64-bit block counter to 96-bit nonce and 32-bit block counter, The name was not changed when the algorithm was modified, as it is cryptographically insignificant (both form what a cryptographer would recognize as a 128-bit nonce), but the interface change could be a source of confusion for developers.
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Meanwhile, the store operations in the loop body receive `None` values until the loop's steady state is reached, and therefore have no effect until real results are available for storing. Thus, the loop body that handles the steady-state of the pipeline code, which includes appropriate `retire` operations, acts as its own prologue code. The processing of the final elements through the pipeline can generally be finished by having this same loop deliberately execute extra iterations, such that the remaining scheduled operations have time to finish and be stored to memory, because nearly all operations have no side effects (attempted invalid memory reads merely produce a `NaR` value on the belt, which does not cause a fault unless it is then used by a store or flow control operation). To pipeline nested loops, the Mill treats each loop almost like a subroutine call, with automatic saves and restores of appropriate state (belt and scratchpad).
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A minimum weight basis of a graphic matroid is a minimum spanning tree (or minimum spanning forest, if the underlying graph is disconnected). Algorithms for computing minimum spanning trees have been intensively studied; it is known how to solve the problem in linear randomized expected time in a comparison model of computation, or in linear time in a model of computation in which the edge weights are small integers and bitwise operations are allowed on their binary representations.. The fastest known time bound that has been proven for a deterministic algorithm is slightly superlinear.. Several authors have investigated algorithms for testing whether a given matroid is graphic.... For instance, an algorithm of solves this problem when the input is known to be a binary matroid. solves this problem for arbitrary matroids given access to the matroid only through an independence oracle, a subroutine that determines whether or not a given set is independent.
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Two equivalent addresses could be compared as non-equal if one of them had the sign bit turned on even if the remaining bits were identical. Most of this was invisible to programmers using high-level languages like COBOL or FORTRAN,"to accommodate large arrays in FORTRAN." and IBM aided the transition with dual mode hardware for a period of time. Certain machine instructions in this 31-bit addressing mode alter the addressing mode bit as a possibly intentional side effect. For example, the original subroutine call instructions BAL, Branch and Link, and its register- register equivalent, BALR, Branch and Link Register, store certain status information, the instruction length code,Because the instruction length code is 00b for a BALR and is 01b for a BAL, the high order bit is always guaranteed to be set to 0, thereby indicating 24-bit mode, for BALR and BAL on XA and later systems.
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Raising the interrupt input to the computer causes a break in execution as follows: as soon as the machine is in a suitable state (in particular, when not "busy" and only in certain states of the fetch/execute cycle), the next instruction pair is fetched from store location 5, without changing the Sequence Control Register (SCR). Location 5 is expected to contain a standard subroutine entry instruction pair (73 LINK : 40 N – see above), allowing the pre-interrupt execution address (still in the SCR) to be saved for later return. The external equipment raising the interrupt is relied upon to refrain from raising another interrupt until the first has been acknowledged by some suitable input/output instruction, so as to prevent interrupts from being nested. The Algol compiler does not regard location 5 as a reserved location, although this may have more to do with the unsuitability of Algol for process control applications than indicating that interrupts are never regarded as a mainstream facility.
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Davis makes a persuasive argument that Turing's conception of what is now known as "the stored-program computer", of placing the "action table"—the instructions for the machine—in the same "memory" as the input data, strongly influenced John von Neumann's conception of the first American discrete-symbol (as opposed to analog) computer—the EDVAC. Davis quotes Time magazine to this effect, that "everyone who taps at a keyboard... is working on an incarnation of a Turing machine," and that "John von Neumann [built] on the work of Alan Turing" (Davis 2000:193 quoting Time magazine of 29 March 1999). Davis makes a case that Turing's Automatic Computing Engine (ACE) computer "anticipated" the notions of microprogramming (microcode) and RISC processors (Davis 2000:188). Knuth cites Turing's work on the ACE computer as designing "hardware to facilitate subroutine linkage" (Knuth 1973:225); Davis also references this work as Turing's use of a hardware "stack" (Davis 2000:237 footnote 18).
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In object-oriented programming, a class is an extensible program-code-template for creating objects, providing initial values for state (member variables) and implementations of behavior (member functions or methods). In many languages, the class name is used as the name for the class (the template itself), the name for the default constructor of the class (a subroutine that creates objects), and as the type of objects generated by instantiating the class; these distinct concepts are easily conflated. When an object is created by a constructor of the class, the resulting object is called an instance of the class, and the member variables specific to the object are called instance variables, to contrast with the class variables shared across the class. In some languages, classes are only a compile-time feature (new classes cannot be declared at run-time), while in other languages classes are first-class citizens, and are generally themselves objects (typically of type or similar).
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In computer science, counting sort is an algorithm for sorting a collection of objects according to keys that are small integers; that is, it is an integer sorting algorithm. It operates by counting the number of objects that have each distinct key value, and using arithmetic on those counts to determine the positions of each key value in the output sequence. Its running time is linear in the number of items and the difference between the maximum and minimum key values, so it is only suitable for direct use in situations where the variation in keys is not significantly greater than the number of items. However, it is often used as a subroutine in another sorting algorithm, radix sort, that can handle larger keys more efficiently.. See also the historical notes on page 181... Because counting sort uses key values as indexes into an array, it is not a comparison sort, and the Ω(n log n) lower bound for comparison sorting does not apply to it.
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For example, as mentioned above, the time complexity of binary search depends on whether a Turing machine or a random access machine is used; but regardless of the machine choice, it lies in P, the class of polynomial-time algorithms. In general, P is considered a machine-independent class because any operation that can be simulated in polynomial time can be assumed to require constant time, since it can be treated as a subroutine without exceeding the polynomial-time bound. Oracle machines are machines that have a specific operation that they can perform in constant time; this operation can be arbitrarily complex and can dramatically affect the complexity of algorithms performed on the machine. For example, if one has an oracle to solve any NP-complete problem, then any problem in NP can be solved in polynomial time (whereas without the oracle, no polynomial-time algorithm is known for many of these problems).
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As stated before, median-of- medians is used as a pivot selection strategy in the quickselect algorithm, which in pseudocode looks as follows. Be careful to handle `left`, `right` and `n` when implementing. It's better to use the same index for `left`, `right` and `n` to avoid handle index converting. Note that this returns the index of the n'th largest number after rearranging the list, rather than the actual value of the n'th largest number. function select(list, left, right, n) loop if left = right then return left pivotIndex := pivot(list, left, right) pivotIndex := partition(list, left, right, pivotIndex, n) if n = pivotIndex then return n else if n < pivotIndex then''' right := pivotIndex - 1 else left := pivotIndex + 1 There is a subroutine called that can, in linear time, group a list (ranging from indices `left` to `right`) into three parts, those less than a certain element, those equal to it, and those greater than the element (a three-way partition).
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Because it is the bipartite half of a distance- regular graph, the halved cube graph is itself distance-regular.. And because it contains a hypercube as a spanning subgraph, it inherits from the hypercube all monotone graph properties, such as the property of containing a Hamiltonian cycle. As with the hypercube graphs, and their isometric (distance-preserving) subgraphs the partial cubes, a halved cube graph may be embedded isometrically into a real vector space with the Manhattan metric (L1 distance function). The same is true for the isometric subgraphs of halved cube graphs, which may be recognized in polynomial time; this forms a key subroutine for an algorithm which tests whether a given graph may be embedded isometrically into a Manhattan metric.. For every halved cube graph of order five or more, it is possible to (improperly) color the vertices with two colors, in such a way that the resulting colored graph has no nontrivial symmetries. For the graphs of order three and four, four colors are needed to eliminate all symmetries..
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Modern languages have a specialized structured construct for exception handling which does not rely on the use of `GOTO` or (multi-level) breaks or returns. For example, in C++ one can write: try { xxx1 // Somewhere in here xxx2 // use: throw someValue; xxx3 } catch (someClass& someId) { // catch value of someClass actionForSomeClass } catch (someType& anotherId) { // catch value of someType actionForSomeType } catch (...) { // catch anything not already caught actionForAnythingElse } Any number and variety of `catch` clauses can be used above. If there is no `catch` matching a particular `throw`, control percolates back through subroutine calls and/or nested blocks until a matching `catch` is found or until the end of the main program is reached, at which point the program is forcibly stopped with a suitable error message. Via C++'s influence, `catch` is the keyword reserved for declaring a pattern-matching exception handler in other languages popular today, like Java or C#. Some other languages like Ada use the keyword `exception` to introduce an exception handler and then may even employ a different keyword (`when` in Ada) for the pattern matching.
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As the Turing Machine was encouraging the construction of computers, the UTM was encouraging the development of the fledgling computer sciences. An early, if not the very first, assembler was proposed "by a young hot-shot programmer" for the EDVAC (Davis 2000:192). Von Neumann's "first serious program ... [was] to simply sort data efficiently" (Davis 2000:184). Knuth observes that the subroutine return embedded in the program itself rather than in special registers is attributable to von Neumann and Goldstine.In particular: Burks, Goldstine, von Neumann (1946), Preliminary discussion of the logical design of an electronic computing instrument, reprinted in Bell and Newell 1971 Knuth furthermore states that :"The first interpretive routine may be said to be the "Universal Turing Machine" ... Interpretive routines in the conventional sense were mentioned by John Mauchly in his lectures at the Moore School in 1946 ... Turing took part in this development also; interpretive systems for the Pilot ACE computer were written under his direction" (Knuth 1973:226). Davis briefly mentions operating systems and compilers as outcomes of the notion of program- as-data (Davis 2000:185).
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While Fox influenced the development of numerical analysis through his undergraduate teaching and postgraduate supervision (he supervised around 19 doctoral students), industrial collaboration he also made significant contributions to course material for the Open University. He lectured widely on 'meaningless answers', describing some of the pitfalls of numerical computation from the uncritical use of simple methods Fox played a significant part in the early days of the Numerical Algorithms Group (NAG), which set out as a collaborative venture between Oxford, Nottingham and Manchester to provide a reliable and well-tested mathematical subroutine library. The Oxford Computing Laboratory was one of the founder members of NAG when it started in 1970, and Fox supported it strongly and he became a member of its council when the Group was incorporated in 1976 continuing in this capacity until 1984. Fox was an active member of the Institute of Mathematics and its Applications from its beginnings, as a member of the Council and as an editor first of the main 'IMA Journal and later the specialised Journal of Numerical Analysis, started in 1981.
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Kelly's proof of the existence of an ordinary line can be turned into an algorithm that finds an ordinary line by searching for the closest pair of a point and a line through two other points. report the time for this closest-pair search as O(n^3), based on a brute-force search of all triples of points, but an algorithm to find the closest given point to each line through two given points, in time O(n^2), was given earlier by , as a subroutine for finding the minimum-area triangle determined by three of a given set of points. The same paper of also shows how to construct the dual arrangement of lines to the given points (as used in Melchior and Steenrod's proof) in the same time, O(n^2), from which it is possible to identify all ordinary vertices and all ordinary lines. first showed how to find a single ordinary line (not necessarily the one from Kelly's proof) in time O(n\log n), and a simpler algorithm with the same time bound was described by .
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Additional instructions in support of 24/31-bit addressing include two new register-register call/return instructions which also effect an addressing mode change (e.g. Branch and Save and Set Mode, BASSM,"BASSM (branch and save and set mode)" the 24/31 bit version of a call where the linkage address including the mode is saved and a branch is taken to an address in a possibly different mode, and BSM, Branch and Set Mode, the 24/31 bit version of a return, where the return is directly to the previously saved linkage address and in its previous mode). Taken together, BASSM and BSM allow 24-bit calls to 31-bit (and return to 24-bit), 31-bit calls to 24-bit (and return to 31-bit), 24-bit calls to 24-bit (and return to 24-bit) and 31-bit calls to 31-bit (and return to 31-bit). Like BALR 14,15 (the 24-bit- only form of a call), BASSM is used as BASSM 14,15, where the linkage address and mode are saved in register 14, and a branch is taken to the subroutine address and mode specified in register 15.
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In Ramsey theory, parameter words and combinatorial cubes may be used to formulate the Graham–Rothschild theorem, according to which, for every finite alphabet and group action, and every combination of integer values m, k, and r, there exists a sufficiently large number n such that if each combinatorial cube over strings of length n is assigned one of r colors, then there exists a combinatorial cube all of whose subcubes have the same color. This result is a key foundation for structural Ramsey theory, and is used to define Graham's number, an enormous number used to estimate the value of n for a certain combination of values. In computer science, in the problem of searching for duplicate code, the source code for a given routine or module may be transformed into a parameter word by converting it into a sequence of tokens, and for each variable or subroutine name, replacing each copy of the same name with the same wildcard character. If code is duplicated, the resulting parameter words will remain equal even if some of the variables or subroutines have been renamed.
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In computability theory, a Turing reduction (also known as a Cook reduction) from a problem A to a problem B, is a reduction which solves A, assuming the solution to B is already known (Rogers 1967, Soare 1987). It can be understood as an algorithm that could be used to solve A if it had available to it a subroutine for solving B. More formally, a Turing reduction is a function computable by an oracle machine with an oracle for B. Turing reductions can be applied to both decision problems and function problems. If a Turing reduction of A to B exists then every algorithm for B can be used to produce an algorithm for A, by inserting the algorithm for B at each place where the oracle machine computing A queries the oracle for B. However, because the oracle machine may query the oracle a large number of times, the resulting algorithm may require more time asymptotically than either the algorithm for B or the oracle machine computing A, and may require as much space as both together. The first formal definition of relative computability, then called relative reducibility, was given by Alan Turing in 1939 in terms of oracle machines.
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For example, to move the cursor to (10, 15), needed, in 6502 assembler: LDA #31: JSR OSWRCH \ move text cursor LDA #10: JSR OSWRCH \ x-coordinate LDA #15: JSR OSWRCH \ y-coordinate (LDA loads a value into the accumulator; JSR is "jump to subroutine".) On the third OS call, the cursor will move. The following code would draw a line from (0, 0) to (0, +100): LDA #25: JSR OSWRCH \ begin "PLOT" (ASCII 25) command LDA #4: JSR OSWRCH \ command k=4, or move absolute LDA #0: JSR OSWRCH: JSR OSWRCH: JSR OSWRCH: JSR OSWRCH \ send (0, 0) as low, high byte pairs LDA #25: JSR OSWRCH \ begin PLOT LDA #1: JSR OSWRCH \ k=1 - draw relative LDA #0: JSR OSWRCH: JSR OSWRCH \ x = 0 LDA #100: JSR OSWRCH \ y = 100 (low byte) LDA #0: JSR OSWRCH \ high byte BBC BASIC allows performing the above as any of the following: VDU 25, 4, 0; 0; 25, 4, 100; 0; PRINT CHR$(25); CHR$(4); CHR$(0); ... etc. PLOT 4, 0, 0: PLOT 1, 0, 100 MOVE 0, 0: DRAW 0, 100: REM absolute co-ords only! OSWRCH=&FFEE;: A%=25: CALL OSWRCH: A%=4: CALL OSWRCH: A%=0: CALL OSWRCH ... etc.
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