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253d0b2377
1999-10-27 Andreas Jaeger <aj@suse.de> * stdlib/rand_r.c (rand_r): Really use 31 bits, the result was shifted a bit too much. Reported by Eugen Dedu <dedu@ese-metz.fr>.
50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
/* Reentrant random function frm POSIX.1c.
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Copyright (C) 1996, 1999 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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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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}
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