xref: /llvm-project/libcxx/test/std/numerics/rand/rand.eng/rand.eng.lcong/assign.pass.cpp (revision fea29ee41d50c5603338f5af4728ddbdf93aaec2)
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& operator=(const linear_congruential_engine&);
15 
16 #include <random>
17 #include <cassert>
18 #include <climits>
19 
20 #include "test_macros.h"
21 
22 template <class T, T a, T c, T m>
23 void
test1()24 test1()
25 {
26     typedef std::linear_congruential_engine<T, a, c, m> E;
27     E e1;
28     E e2;
29     assert(e1 == e2);
30     (void)e1();
31     e2 = e1;
32     assert(e1 == e2);
33 }
34 
35 template <class T>
36 void
test()37 test()
38 {
39   const int W = sizeof(T) * CHAR_BIT;
40   const T M(static_cast<T>(-1));
41   const T A(static_cast<T>((static_cast<T>(1) << (W / 2)) - 1));
42 
43   // Cases where m = 0
44   test1<T, 0, 0, 0>();
45   test1<T, A, 0, 0>();
46   test1<T, 0, 1, 0>();
47   test1<T, A, 1, 0>();
48 
49   // Cases where m = 2^n for n < w
50   test1<T, 0, 0, 256>();
51   test1<T, 5, 0, 256>();
52   test1<T, 0, 1, 256>();
53   test1<T, 5, 1, 256>();
54 
55   // Cases where m is odd and a = 0
56   test1<T, 0, 0, M>();
57   test1<T, 0, M - 2, M>();
58   test1<T, 0, M - 1, M>();
59 
60   // Cases where m is odd and m % a <= m / a (Schrage)
61   test1<T, A, 0, M>();
62   test1<T, A, M - 2, M>();
63   test1<T, A, M - 1, M>();
64 }
65 
66 template <class T>
test_ext()67 void test_ext() {
68   const T M(static_cast<T>(-1));
69 
70   // Cases where m is odd and m % a > m / a
71   test1<T, M - 2, 0, M>();
72   test1<T, M - 2, M - 2, M>();
73   test1<T, M - 2, M - 1, M>();
74   test1<T, M - 1, 0, M>();
75   test1<T, M - 1, M - 2, M>();
76   test1<T, M - 1, M - 1, M>();
77 }
78 
main(int,char **)79 int main(int, char**)
80 {
81     test<unsigned short>();
82     test_ext<unsigned short>();
83     test<unsigned int>();
84     test_ext<unsigned int>();
85     test<unsigned long>();
86     // This isn't implemented on platforms without __int128
87 #ifndef TEST_HAS_NO_INT128
88     test_ext<unsigned long>();
89 #endif
90     test<unsigned long long>();
91     // This isn't implemented on platforms without __int128
92 #ifndef TEST_HAS_NO_INT128
93     test_ext<unsigned long long>();
94 #endif
95 
96     return 0;
97 }
98