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[/] [or1k/] [trunk/] [linux/] [uClibc/] [libc/] [stdlib/] [drand48-iter.c] - Rev 1325
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/* Copyright (C) 1995, 1996, 2001 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu <mailto:drepper@gnu.ai.mit.edu>>, August 1995. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include <errno.h> #include <stdlib.h> #include <limits.h> #include <stdint.h> #include <sys/types.h> /* Global state for non-reentrant functions. */ struct drand48_data __libc_drand48_data; int __drand48_iterate (unsigned short int xsubi[3], struct drand48_data *buffer) { uint64_t X; uint64_t result; /* Initialize buffer, if not yet done. */ if (unlikely(!buffer->__init)) { buffer->__a = 0x5deece66dull; buffer->__c = 0xb; buffer->__init = 1; } /* Do the real work. We choose a data type which contains at least 48 bits. Because we compute the modulus it does not care how many bits really are computed. */ X = (uint64_t) xsubi[2] << 32 | (uint32_t) xsubi[1] << 16 | xsubi[0]; result = X * buffer->__a + buffer->__c; xsubi[0] = result & 0xffff; xsubi[1] = (result >> 16) & 0xffff; xsubi[2] = (result >> 32) & 0xffff; return 0; }
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