1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// <random>
10
11// template <class UIntType, UIntType a, UIntType c, UIntType m>
12// class linear_congruential_engine;
13
14// linear_congruential_engine();
15
16#include <random>
17#include <cassert>
18#include <climits>
19
20#include "test_macros.h"
21
22template <class T, T a, T c, T m>
23void
24test1()
25{
26 typedef std::linear_congruential_engine<T, a, c, m> LCE;
27 LCE e1;
28 LCE e2;
29 e2.seed();
30 assert(e1 == e2);
31}
32
33template <class T>
34void
35test()
36{
37 const int W = sizeof(T) * CHAR_BIT;
38 const T M(static_cast<T>(-1));
39 const T A(static_cast<T>((static_cast<T>(1) << (W / 2)) - 1));
40
41 // Cases where m = 0
42 test1<T, 0, 0, 0>();
43 test1<T, A, 0, 0>();
44 test1<T, 0, 1, 0>();
45 test1<T, A, 1, 0>();
46
47 // Cases where m = 2^n for n < w
48 test1<T, 0, 0, 256>();
49 test1<T, 5, 0, 256>();
50 test1<T, 0, 1, 256>();
51 test1<T, 5, 1, 256>();
52
53 // Cases where m is odd and a = 0
54 test1<T, 0, 0, M>();
55 test1<T, 0, M - 2, M>();
56 test1<T, 0, M - 1, M>();
57
58 // Cases where m is odd and m % a <= m / a (Schrage)
59 test1<T, A, 0, M>();
60 test1<T, A, M - 2, M>();
61 test1<T, A, M - 1, M>();
62}
63
64template <class T>
65void test_ext() {
66 const T M(static_cast<T>(-1));
67
68 // Cases where m is odd and m % a > m / a
69 test1<T, M - 2, 0, M>();
70 test1<T, M - 2, M - 2, M>();
71 test1<T, M - 2, M - 1, M>();
72 test1<T, M - 1, 0, M>();
73 test1<T, M - 1, M - 2, M>();
74 test1<T, M - 1, M - 1, M>();
75}
76
77int main(int, char**)
78{
79 test<unsigned short>();
80 test_ext<unsigned short>();
81 test<unsigned int>();
82 test_ext<unsigned int>();
83 test<unsigned long>();
84 test_ext<unsigned long>();
85 test<unsigned long long>();
86 // This isn't implemented on platforms without __int128
87#ifndef TEST_HAS_NO_INT128
88 test_ext<unsigned long long>();
89#endif
90
91 return 0;
92}
93

source code of libcxx/test/std/numerics/rand/rand.eng/rand.eng.lcong/default.pass.cpp