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1219ddfe | 1 | /* Reentrant random function from POSIX.1c. |
b168057a | 2 | Copyright (C) 1996-2015 Free Software Foundation, Inc. |
84384f5b | 3 | This file is part of the GNU C Library. |
a18f587d | 4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. |
28f540f4 | 5 | |
84384f5b | 6 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
28f540f4 | 10 | |
84384f5b UD |
11 | The GNU C Library is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 14 | Lesser General Public License for more details. |
28f540f4 | 15 | |
41bdb6e2 | 16 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ | |
28f540f4 | 19 | |
a18f587d UD |
20 | #include <stdlib.h> |
21 | ||
22 | ||
23 | /* This algorithm is mentioned in the ISO C standard, here extended | |
24 | for 32 bits. */ | |
25 | int | |
26 | rand_r (unsigned int *seed) | |
27 | { | |
28 | unsigned int next = *seed; | |
29 | int result; | |
30 | ||
31 | next *= 1103515245; | |
32 | next += 12345; | |
33 | result = (unsigned int) (next / 65536) % 2048; | |
34 | ||
35 | next *= 1103515245; | |
36 | next += 12345; | |
253d0b23 | 37 | result <<= 10; |
a18f587d UD |
38 | result ^= (unsigned int) (next / 65536) % 1024; |
39 | ||
40 | next *= 1103515245; | |
41 | next += 12345; | |
42 | result <<= 10; | |
43 | result ^= (unsigned int) (next / 65536) % 1024; | |
44 | ||
45 | *seed = next; | |
46 | ||
47 | return result; | |
48 | } |