| /* Copyright (C) 1995-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Ulrich Drepper <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, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #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 (__glibc_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; |
| } |