libcxx/test/std/numerics/rand/rand.eng/rand.eng.lcong/copy.pass.cpp

   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(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
  24 test1()
  25 {
  26     typedef std::linear_congruential_engine<T, a, c, m> E;
  27     E e1;
  28     E e2 = e1;
  29     assert(e1 == e2);
  30     (void)e1();
  31     (void)e2();
  32     assert(e1 == e2);
  33 }
  34
  35 template <class T>
  36 void
  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>
  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
  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 }