1/* Reentrant random function from POSIX.1c.
2 Copyright (C) 1996-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <stdlib.h>
20
21
22/* This algorithm is mentioned in the ISO C standard, here extended
23 for 32 bits. */
24int
25rand_r (unsigned int *seed)
26{
27 unsigned int next = *seed;
28 int result;
29
30 next *= 1103515245;
31 next += 12345;
32 result = (unsigned int) (next / 65536) % 2048;
33
34 next *= 1103515245;
35 next += 12345;
36 result <<= 10;
37 result ^= (unsigned int) (next / 65536) % 1024;
38
39 next *= 1103515245;
40 next += 12345;
41 result <<= 10;
42 result ^= (unsigned int) (next / 65536) % 1024;
43
44 *seed = next;
45
46 return result;
47}
48