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581c785b | 1 | /* Copyright (C) 1995-2022 Free Software Foundation, Inc. |
84384f5b | 2 | This file is part of the GNU C Library. |
60478656 | 3 | |
84384f5b | 4 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
60478656 | 8 | |
84384f5b UD |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
60478656 | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 15 | License along with the GNU C Library; if not, see |
5a82c748 | 16 | <https://www.gnu.org/licenses/>. */ |
60478656 RM |
17 | |
18 | #include <errno.h> | |
19 | #include <stdlib.h> | |
1d8dc429 | 20 | #include <limits.h> |
d17c01f9 | 21 | #include <stdint.h> |
52e9a9d1 | 22 | #include <sys/types.h> |
60478656 | 23 | |
845dcb57 | 24 | /* Global state for non-reentrant functions. */ |
60478656 RM |
25 | struct drand48_data __libc_drand48_data; |
26 | ||
27 | ||
28 | int | |
a72ddc14 | 29 | __drand48_iterate (unsigned short int xsubi[3], struct drand48_data *buffer) |
60478656 | 30 | { |
d17c01f9 UD |
31 | uint64_t X; |
32 | uint64_t result; | |
60478656 RM |
33 | |
34 | /* Initialize buffer, if not yet done. */ | |
a1ffb40e | 35 | if (__glibc_unlikely (!buffer->__init)) |
60478656 | 36 | { |
d17c01f9 UD |
37 | buffer->__a = 0x5deece66dull; |
38 | buffer->__c = 0xb; | |
39 | buffer->__init = 1; | |
60478656 RM |
40 | } |
41 | ||
42 | /* Do the real work. We choose a data type which contains at least | |
43 | 48 bits. Because we compute the modulus it does not care how | |
44 | many bits really are computed. */ | |
45 | ||
d17c01f9 | 46 | X = (uint64_t) xsubi[2] << 32 | (uint32_t) xsubi[1] << 16 | xsubi[0]; |
52e9a9d1 | 47 | |
d17c01f9 | 48 | result = X * buffer->__a + buffer->__c; |
52e9a9d1 | 49 | |
d17c01f9 UD |
50 | xsubi[0] = result & 0xffff; |
51 | xsubi[1] = (result >> 16) & 0xffff; | |
52 | xsubi[2] = (result >> 32) & 0xffff; | |
60478656 RM |
53 | |
54 | return 0; | |
55 | } |