48 lines
1.3 KiB
C
48 lines
1.3 KiB
C
/* Reentrant random function from POSIX.1c.
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Copyright (C) 1996-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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<https://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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}
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