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239c2bf93e
* libc/misc/unctrl.c: Replace FUNCTION description.
* libc/signal/signal.c: Remove documentation for raise and _raise_r.
* libc/stdio/getdelim.c: Fix spelling errors.
* libc/stdio/getw.c: Put RETURNS on a separate line. Fix punctuation.
* libc/stdio/putw.c: Likewise.
* libc/stdlib/a64l.c: Fix formatting, spelling and punctuation in
documentation.
* libc/stdlib/assert.c: Do not capitalize FUNCTION description.
* libc/stdlib/efgcvt.c: Add spaces to FUNCTION description.
* libc/stdlib/envlock.c: Use em-dash in FUNCTION description.
* libc/stdlib/mlock.c: Likewise.
* libc/stdlib/mstats.c: Likewise.
* libc/time/tzlock.c: Likewise.
* libc/stdlib/rand.c: Use "multi-threaded" and "thread-safe" in NOTES.
* libc/stdlib/rand48.c: Remove extra space in FUNCTION description
and hyphenate "pseudo-random".
* libc/string/bcmp.c: Remove extra blank lines in documentation.
* libc/string/strncat.c: Likewise.
* libc/string/memchr.c: Remove extra ">" character in documentation.
* libc/string/strcspn.c: Use "characters" instead of "chars".
* libc/string/strpbrk.c: Likewise.
* libc/string/strerror_r.c: Capitalize "GNU".
* libc/string/strnlen.c: Likewise.
* libc/string/strtok.c: Fix formatting, spelling and punctuation in
documentation. Use "multi-threaded" and "thread-safe" in NOTES.
* libc/string/wcscat.c: Split PORTABILITY into two paragraphs.
* libc/string/wcschr.c: Likewise.
* libc/string/wcscmp.c: Likewise.
* libc/string/wcscpy.c: Likewise.
* libc/string/wcscspn.c: Likewise.
* libc/string/wcslen.c: Likewise.
* libc/string/wcsncat.c: Likewise.
* libc/string/wcsncmp.c: Likewise.
* libc/string/wcsncpy.c: Likewise.
* libc/string/wcsnlen.c: Likewise.
* libc/string/wcspbrk.c: Likewise.
* libc/string/wcsrchr.c: Likewise.
* libc/string/wcsspn.c: Likewise.
* libc/string/wmemchr.c: Likewise.
* libc/string/wmemcmp.c: Likewise.
* libc/string/wmemcpy.c: Likewise.
* libc/string/wmemset.c: Likewise.
* libc/string/wmemmove.c: Likewise. Also fix FUNCTION description.
* libc/string/wcswidth.c: Formatting and punctuation in documentation.
* libc/string/wcwidth.c: Likewise.
* libm/common/s_modf.c: Remove extra period from documentation.
* libm/math/s_isnan.c: Fix formatting, grammar and punctuation in
documentation.
* libm/mathfp/s_isnan.c: Likewise.
* libm/math/s_ldexp.c: Fix punctuation.
* libm/mathfp/s_ldexp.c: Likewise.
* libm/math/w_log.c: Likewise.
* libm/mathfp/s_logarithm.c: Likewise.
* libm/math/w_j0.c: Add spaces to FUNCTION description.
* libm/mathfp/w_jn.c: Likewise.
91 lines
2.5 KiB
C
91 lines
2.5 KiB
C
/*
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FUNCTION
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<<rand>>, <<srand>>---pseudo-random numbers
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INDEX
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rand
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INDEX
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srand
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INDEX
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rand_r
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ANSI_SYNOPSIS
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#include <stdlib.h>
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int rand(void);
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void srand(unsigned int <[seed]>);
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int rand_r(unsigned int *<[seed]>);
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TRAD_SYNOPSIS
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#include <stdlib.h>
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int rand();
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void srand(<[seed]>)
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unsigned int <[seed]>;
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void rand_r(<[seed]>)
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unsigned int *<[seed]>;
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DESCRIPTION
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<<rand>> returns a different integer each time it is called; each
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integer is chosen by an algorithm designed to be unpredictable, so
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that you can use <<rand>> when you require a random number.
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The algorithm depends on a static variable called the ``random seed'';
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starting with a given value of the random seed always produces the
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same sequence of numbers in successive calls to <<rand>>.
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You can set the random seed using <<srand>>; it does nothing beyond
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storing its argument in the static variable used by <<rand>>. You can
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exploit this to make the pseudo-random sequence less predictable, if
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you wish, by using some other unpredictable value (often the least
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significant parts of a time-varying value) as the random seed before
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beginning a sequence of calls to <<rand>>; or, if you wish to ensure
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(for example, while debugging) that successive runs of your program
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use the same ``random'' numbers, you can use <<srand>> to set the same
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random seed at the outset.
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RETURNS
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<<rand>> returns the next pseudo-random integer in sequence; it is a
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number between <<0>> and <<RAND_MAX>> (inclusive).
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<<srand>> does not return a result.
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NOTES
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<<rand>> and <<srand>> are unsafe for multi-threaded applications.
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<<rand_r>> is thread-safe and should be used instead.
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PORTABILITY
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<<rand>> is required by ANSI, but the algorithm for pseudo-random
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number generation is not specified; therefore, even if you use
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the same random seed, you cannot expect the same sequence of results
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on two different systems.
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<<rand>> requires no supporting OS subroutines.
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*/
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#ifndef _REENT_ONLY
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#include <stdlib.h>
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#include <reent.h>
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void
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_DEFUN (srand, (seed), unsigned int seed)
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{
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_REENT_RAND_NEXT(_REENT) = seed;
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}
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int
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_DEFUN_VOID (rand)
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{
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/* This multiplier was obtained from Knuth, D.E., "The Art of
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Computer Programming," Vol 2, Seminumerical Algorithms, Third
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Edition, Addison-Wesley, 1998, p. 106 (line 26) & p. 108 */
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_REENT_CHECK_RAND48(_REENT);
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_REENT_RAND_NEXT(_REENT) =
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_REENT_RAND_NEXT(_REENT) * __extension__ 6364136223846793005LL + 1;
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return (int)((_REENT_RAND_NEXT(_REENT) >> 32) & RAND_MAX);
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}
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#endif /* _REENT_ONLY */
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