ceph/src/boost/libs/multiprecision/test/test_unchecked_cpp_int.cpp

   1 ///////////////////////////////////////////////////////////////
   2 //  Copyright 2017 John Maddock. Distributed under the Boost
   3 //  Software License, Version 1.0. (See accompanying file
   4 //  LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
   5
   6 //
   7 // Check results of truncated overflow.
   8 //
   9
  10 #ifdef _MSC_VER
  11 #define _SCL_SECURE_NO_WARNINGS
  12 #endif
  13
  14 #include <boost/multiprecision/cpp_int.hpp>
  15 #include "test.hpp"
  16 #include <boost/random/mersenne_twister.hpp>
  17 #include <boost/random/uniform_int.hpp>
  18
  19 template <class T>
  20 T generate_random(unsigned bits_wanted)
  21 {
  22    static boost::random::mt19937               gen;
  23    typedef boost::random::mt19937::result_type random_type;
  24
  25    T        max_val;
  26    unsigned digits;
  27    if (std::numeric_limits<T>::is_bounded && (bits_wanted == (unsigned)std::numeric_limits<T>::digits))
  28    {
  29       max_val = (std::numeric_limits<T>::max)();
  30       digits  = std::numeric_limits<T>::digits;
  31    }
  32    else
  33    {
  34       max_val = T(1) << bits_wanted;
  35       digits  = bits_wanted;
  36    }
  37
  38    unsigned bits_per_r_val = std::numeric_limits<random_type>::digits - 1;
  39    while ((random_type(1) << bits_per_r_val) > (gen.max)())
  40       --bits_per_r_val;
  41
  42    unsigned terms_needed = digits / bits_per_r_val + 1;
  43
  44    T val = 0;
  45    for (unsigned i = 0; i < terms_needed; ++i)
  46    {
  47       val *= (gen.max)();
  48       val += gen();
  49    }
  50    val %= max_val;
  51    return val;
  52 }
  53
  54 template <class Number>
  55 void test()
  56 {
  57    using namespace boost::multiprecision;
  58    typedef Number test_type;
  59
  60    for (unsigned i = 30; i < std::numeric_limits<test_type>::digits; ++i)
  61    {
  62       for (unsigned j = std::numeric_limits<test_type>::digits - i - 1; j < std::numeric_limits<test_type>::digits; ++j)
  63       {
  64          for (unsigned k = 0; k < 10; ++k)
  65          {
  66             test_type a = static_cast<test_type>(generate_random<cpp_int>(i));
  67             test_type b = static_cast<test_type>(generate_random<cpp_int>(j));
  68             test_type c = static_cast<test_type>(cpp_int(a) * cpp_int(b));
  69             test_type d = a * b;
  70             BOOST_CHECK_EQUAL(c, d);
  71
  72             if ((k == 0) && (j == 0))
  73             {
  74                for (unsigned s = 1; s < std::numeric_limits<test_type>::digits; ++s)
  75                   BOOST_CHECK_EQUAL(a << s, test_type(cpp_int(a) << s));
  76             }
  77          }
  78       }
  79    }
  80 }
  81
  82 int main()
  83 {
  84    using namespace boost::multiprecision;
  85
  86    test<int512_t>();
  87    test<uint512_t>();
  88
  89    //
  90    // We also need to test type with "odd" bit counts in order to ensure full code coverage:
  91    //
  92    test<number<cpp_int_backend<528, 528, signed_magnitude, unchecked, void> > >();
  93    test<number<cpp_int_backend<528, 528, unsigned_magnitude, unchecked, void> > >();
  94    test<number<cpp_int_backend<48, 48, signed_magnitude, unchecked, void> > >();
  95    test<number<cpp_int_backend<48, 48, unsigned_magnitude, unchecked, void> > >();
  96    return boost::report_errors();
  97 }