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// public:
15// engine characteristics
16// static constexpr result_type multiplier = a;
17// static constexpr result_type increment = c;
18// static constexpr result_type modulus = m;
19// static constexpr result_type min() { return c == 0u ? 1u: 0u;}
20// static constexpr result_type max() { return m - 1u;}
21// static constexpr result_type default_seed = 1u;
22
23#include <random>
24#include <cassert>
25#include <climits>
26#include <type_traits>
27
28#include "test_macros.h"
29
30template <class T>
31void where(const T &) {}
32
33template <class T, T a, T c, T m>
34void
35test1()
36{
37 typedef std::linear_congruential_engine<T, a, c, m> LCE;
38 typedef typename LCE::result_type result_type;
39 static_assert((LCE::multiplier == a), "");
40 static_assert((LCE::increment == c), "");
41 static_assert((LCE::modulus == m), "");
42#if TEST_STD_VER >= 11
43 static_assert((LCE::min() == (c == 0u ? 1u: 0u)), "");
44#else
45 assert((LCE::min() == (c == 0u ? 1u: 0u)));
46#endif
47
48 TEST_DIAGNOSTIC_PUSH
49 TEST_MSVC_DIAGNOSTIC_IGNORED(4310) // cast truncates constant value
50
51#if TEST_STD_VER >= 11
52 static_assert((LCE::max() == result_type(m - 1u)), "");
53#else
54 assert((LCE::max() == result_type(m - 1u)));
55#endif
56
57 TEST_DIAGNOSTIC_POP
58
59 static_assert((LCE::default_seed == 1), "");
60 where(LCE::multiplier);
61 where(LCE::increment);
62 where(LCE::modulus);
63 where(LCE::default_seed);
64}
65
66template <class T>
67void
68test()
69{
70 const int W = sizeof(T) * CHAR_BIT;
71 const T M(static_cast<T>(-1));
72 const T A(static_cast<T>((static_cast<T>(1) << (W / 2)) - 1));
73
74 // Cases where m = 0
75 test1<T, 0, 0, 0>();
76 test1<T, A, 0, 0>();
77 test1<T, 0, 1, 0>();
78 test1<T, A, 1, 0>();
79
80 // Cases where m = 2^n for n < w
81 test1<T, 0, 0, 256>();
82 test1<T, 5, 0, 256>();
83 test1<T, 0, 1, 256>();
84 test1<T, 5, 1, 256>();
85
86 // Cases where m is odd and a = 0
87 test1<T, 0, 0, M>();
88 test1<T, 0, M - 2, M>();
89 test1<T, 0, M - 1, M>();
90
91 // Cases where m is odd and m % a <= m / a (Schrage)
92 test1<T, A, 0, M>();
93 test1<T, A, M - 2, M>();
94 test1<T, A, M - 1, M>();
95}
96
97template <class T>
98void test_ext() {
99 const T M(static_cast<T>(-1));
100
101 // Cases where m is odd and m % a > m / a
102 test1<T, M - 2, 0, M>();
103 test1<T, M - 2, M - 2, M>();
104 test1<T, M - 2, M - 1, M>();
105 test1<T, M - 1, 0, M>();
106 test1<T, M - 1, M - 2, M>();
107 test1<T, M - 1, M - 1, M>();
108}
109
110int main(int, char**)
111{
112 test<unsigned short>();
113 test_ext<unsigned short>();
114 test<unsigned int>();
115 test_ext<unsigned int>();
116 test<unsigned long>();
117 test_ext<unsigned long>();
118 test<unsigned long long>();
119 // This isn't implemented on platforms without __int128
120#ifndef TEST_HAS_NO_INT128
121 test_ext<unsigned long long>();
122#endif
123
124 return 0;
125}
126

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