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
19#include "test_macros.h"
20
21template <class T, T a, T c, T m>
22void
23test1()
24{
25 typedef std::linear_congruential_engine<T, a, c, m> LCE;
26 LCE e1;
27 LCE e2;
28 e2.seed();
29 assert(e1 == e2);
30}
31
32template <class T>
33void
34test()
35{
36 const int W = sizeof(T) * CHAR_BIT;
37 const T M(static_cast<T>(-1));
38 const T A(static_cast<T>((static_cast<T>(1) << (W / 2)) - 1));
39
40 // Cases where m = 0
41 test1<T, 0, 0, 0>();
42 test1<T, A, 0, 0>();
43 test1<T, 0, 1, 0>();
44 test1<T, A, 1, 0>();
45
46 // Cases where m = 2^n for n < w
47 test1<T, 0, 0, 256>();
48 test1<T, 5, 0, 256>();
49 test1<T, 0, 1, 256>();
50 test1<T, 5, 1, 256>();
51
52 // Cases where m is odd and a = 0
53 test1<T, 0, 0, M>();
54 test1<T, 0, M - 2, M>();
55 test1<T, 0, M - 1, M>();
56
57 // Cases where m is odd and m % a <= m / a (Schrage)
58 test1<T, A, 0, M>();
59 test1<T, A, M - 2, M>();
60 test1<T, A, M - 1, M>();
61}
62
63template <class T>
64void test_ext() {
65 const T M(static_cast<T>(-1));
66
67 // Cases where m is odd and m % a > m / a
68 test1<T, M - 2, 0, M>();
69 test1<T, M - 2, M - 2, M>();
70 test1<T, M - 2, M - 1, M>();
71 test1<T, M - 1, 0, M>();
72 test1<T, M - 1, M - 2, M>();
73 test1<T, M - 1, M - 1, M>();
74}
75
76int main(int, char**)
77{
78 test<unsigned short>();
79 test_ext<unsigned short>();
80 test<unsigned int>();
81 test_ext<unsigned int>();
82 test<unsigned long>();
83 test_ext<unsigned long>();
84 test<unsigned long long>();
85 // This isn't implemented on platforms without __int128
86#ifndef _LIBCPP_HAS_NO_INT128
87 test_ext<unsigned long long>();
88#endif
89
90 return 0;
91}
92

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