56 lines
2.5 KiB
Plaintext
56 lines
2.5 KiB
Plaintext
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Program: GNU bc
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Author: Philip A. Nelson
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E-mail: phil@cs.wwu.edu
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OS: UNIX (BSD, System V, MINIX, POSIX)
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Copying: GNU GPL version 2
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Copyright holder: Free Software Foundation, Inc.
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Version: bc version 1.01
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Required: vsprintf and vfprintf routines.
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Machines: It has been compiled and run on the following environments:
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BSD4.3 (VAX 11)
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MINIX 1.5 (IBM PC, both K&R and ANSI compilers)
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MINIX 1.5 (pc532)
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SUN-OS 4.1 (SUN 3 and SUN 4)
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SVR3V5 (Motorola 68K)
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SVR3.2 (3B2)
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SVR4.0.2 (a 386 box)
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ULTRIX 4.1 (DEC 5000)
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UTS (Amdahl)
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bc is an arbitrary precision numeric processing language. Syntax is
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similar to C, but differs in many substantial areas. It supports
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interactive execution of statements. bc is a utility included in the
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POSIX P1003.2/D11 draft standard.
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This version was written to be a POSIX compliant bc processor with
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several extensions to the draft standard. Option flags are available
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to cause warning or rejection of the extensions to the POSIX standard.
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For those who want only POSIX bc with no extensions, a grammar is
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provided for exactly the language described in the POSIX document.
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The grammar (sbc.y) comes from the POSIX document. The Makefile
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contains rules to make sbc. (for Standard BC)
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Since the POSIX document does not specify how bc must be implemented,
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this version does not use the historical method of having bc be a
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compiler for the dc calculator. This version has a single executable
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that both compiles the language and runs the a resulting "byte code".
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The "byte code" is NOT the dc language.
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Also, included in the initial distribution is the library file
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vfprintf.c for MINIX systems. My minix 1.5 did not have this file.
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Also, you should verify that vsprintf.c works correctly on your
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system.
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The extensions add some features I think are missing. The major
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changes and additions for bc are (a) names are allowed to be full
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identifiers ([a-z][a-z0-9_]*), (b) addition of the &&, ||, and !
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operators, (c) allowing comparison and boolean operations in any
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expression, (d) addition of an else clause to the if statement, (e)
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addition of a new standard function "read()" that reads a number from
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the standard input under program control, (f) passing of arrays as
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parameters by variable, (g) addition of the "halt" statement that is
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an executable statement unlike the quit (i.e. "if (1 == 0) quit" will
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halt bc but "if (1 == 0) halt" will not halt bc.), and (h) the
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addition of the special variable "last" that is assigned the value of
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each print as the number is printed.
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