Blame stdlib/rand_r.c

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/* Reentrant random function from POSIX.1c.
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   Copyright (C) 1996-2018 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <http://www.gnu.org/licenses/>.  */
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#include <stdlib.h>
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/* This algorithm is mentioned in the ISO C standard, here extended
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   for 32 bits.  */
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int
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rand_r (unsigned int *seed)
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{
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  unsigned int next = *seed;
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  int result;
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  next *= 1103515245;
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  next += 12345;
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  result = (unsigned int) (next / 65536) % 2048;
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  next *= 1103515245;
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  next += 12345;
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  result <<= 10;
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  result ^= (unsigned int) (next / 65536) % 1024;
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  next *= 1103515245;
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  next += 12345;
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  result <<= 10;
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  result ^= (unsigned int) (next / 65536) % 1024;
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  *seed = next;
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  return result;
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}