1/* Reentrant random function from POSIX.1c.
2 Copyright (C) 1996-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
5
6 The GNU C Library is free software; you can redistribute it and/or
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.
10
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
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <stdlib.h>
21
22
23/* This algorithm is mentioned in the ISO C standard, here extended
24 for 32 bits. */
25int
26rand_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;
37 result <<= 10;
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}
49