1/*
2 * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include "../testutil.h"
11
12/*
13 * This is an implementation of the algorithm used by the GNU C library's
14 * random(3) pseudorandom number generator as described:
15 *      https://www.mscs.dal.ca/~selinger/random/
16 */
17static uint32_t test_random_state[31];
18
19uint32_t test_random(void) {
20    static unsigned int pos = 3;
21
22    if (pos == 31)
23        pos = 0;
24    test_random_state[pos] += test_random_state[(pos + 28) % 31];
25    return test_random_state[pos++] / 2;
26}
27
28void test_random_seed(uint32_t sd) {
29    int i;
30    int32_t s;
31    const unsigned int mod = (1u << 31) - 1;
32
33    test_random_state[0] = sd;
34    for (i = 1; i < 31; i++) {
35        s = (int32_t)test_random_state[i - 1];
36        test_random_state[i] = (uint32_t)((16807 * (int64_t)s) % mod);
37    }
38    for (i = 34; i < 344; i++)
39        test_random();
40}
41