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/*- | ||
* Copyright (c) 1990, 1993 | ||
* The Regents of the University of California. All rights reserved. | ||
* | ||
* Redistribution and use in source and binary forms, with or without | ||
* modification, are permitted provided that the following conditions | ||
* are met: | ||
* 1. Redistributions of source code must retain the above copyright | ||
* notice, this list of conditions and the following disclaimer. | ||
* 2. Redistributions in binary form must reproduce the above copyright | ||
* notice, this list of conditions and the following disclaimer in the | ||
* documentation and/or other materials provided with the distribution. | ||
* 3. Neither the name of the University nor the names of its contributors | ||
* may be used to endorse or promote products derived from this software | ||
* without specific prior written permission. | ||
* | ||
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | ||
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | ||
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | ||
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | ||
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | ||
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | ||
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | ||
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | ||
* SUCH DAMAGE. | ||
* | ||
* Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>. | ||
* | ||
* $Id$ | ||
*/ | ||
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/* | ||
* From: | ||
static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93"; | ||
*/ | ||
#ifndef RANDOM_MAX | ||
#define RANDOM_MAX 0x7FFFFFFF | ||
#endif | ||
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#include <stdlib.h> | ||
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static long | ||
do_random(unsigned long *ctx) | ||
{ | ||
/* | ||
* Compute x = (7^5 * x) mod (2^31 - 1) | ||
* wihout overflowing 31 bits: | ||
* (2^31 - 1) = 127773 * (7^5) + 2836 | ||
* From "Random number generators: good ones are hard to find", | ||
* Park and Miller, Communications of the ACM, vol. 31, no. 10, | ||
* October 1988, p. 1195. | ||
*/ | ||
long hi, lo, x; | ||
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x = *ctx; | ||
/* Can't be initialized with 0, so use another value. */ | ||
if (x == 0) | ||
x = 123459876L; | ||
hi = x / 127773L; | ||
lo = x % 127773L; | ||
x = 16807L * lo - 2836L * hi; | ||
if (x < 0) | ||
x += 0x7fffffffL; | ||
return ((*ctx = x) % ((unsigned long)RANDOM_MAX + 1)); | ||
} | ||
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long | ||
random_r(unsigned long *ctx) | ||
{ | ||
return do_random(ctx); | ||
} | ||
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static unsigned long next = 1; | ||
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long | ||
random(void) | ||
{ | ||
return do_random(&next); | ||
} | ||
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void | ||
srandom(unsigned long seed) | ||
{ | ||
next = seed; | ||
} | ||
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