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57 lines
1.7 KiB
C
57 lines
1.7 KiB
C
/* Copyright (C) 1995-2017 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@gnu.ai.mit.edu>, August 1995.
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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 <errno.h>
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#include <stdlib.h>
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#include <limits.h>
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#include <stdint.h>
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#include <sys/types.h>
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/* Global state for non-reentrant functions. */
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struct drand48_data __libc_drand48_data;
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int
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__drand48_iterate (unsigned short int xsubi[3], struct drand48_data *buffer)
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{
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uint64_t X;
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uint64_t result;
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/* Initialize buffer, if not yet done. */
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if (__glibc_unlikely (!buffer->__init))
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{
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buffer->__a = 0x5deece66dull;
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buffer->__c = 0xb;
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buffer->__init = 1;
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}
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/* Do the real work. We choose a data type which contains at least
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48 bits. Because we compute the modulus it does not care how
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many bits really are computed. */
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X = (uint64_t) xsubi[2] << 32 | (uint32_t) xsubi[1] << 16 | xsubi[0];
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result = X * buffer->__a + buffer->__c;
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xsubi[0] = result & 0xffff;
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xsubi[1] = (result >> 16) & 0xffff;
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xsubi[2] = (result >> 32) & 0xffff;
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return 0;
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}
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