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 http://www.boost.org/LICENSE_1_
   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)()) --bits_per_r_val;
  40
  41    unsigned terms_needed = digits / bits_per_r_val + 1;
  42
  43    T val = 0;
  44    for(unsigned i = 0; i < terms_needed; ++i)
  45    {
  46       val *= (gen.max)();
  47       val += gen();
  48    }
  49    val %= max_val;
  50    return val;
  51 }
  52
  53
  54 template <class Number>
  55 void test()
  56 {
  57    using namespace boost::multiprecision;
  58    typedef Number test_type;
  59
  60
  61    for(unsigned i = 30; i < std::numeric_limits<test_type>::digits; ++i)
  62    {
  63       for(unsigned j = std::numeric_limits<test_type>::digits - i - 1; j < std::numeric_limits<test_type>::digits; ++j)
  64       {
  65          for(unsigned k = 0; k < 10; ++k)
  66          {
  67             test_type a = static_cast<test_type>(generate_random<cpp_int>(i));
  68             test_type b = static_cast<test_type>(generate_random<cpp_int>(j));
  69             test_type c = static_cast<test_type>(cpp_int(a) * cpp_int(b));
  70             test_type d = a * b;
  71             BOOST_CHECK_EQUAL(c, d);
  72
  73             if((k == 0) && (j == 0))
  74             {
  75                for(unsigned s = 1; s < std::numeric_limits<test_type>::digits; ++s)
  76                   BOOST_CHECK_EQUAL(a << s, test_type(cpp_int(a) << s));
  77             }
  78          }
  79       }
  80    }
  81 }
  82
  83 int main()
  84 {
  85    using namespace boost::multiprecision;
  86
  87    test<int512_t>();
  88    test<uint512_t>();
  89
  90    //
  91    // We also need to test type with "odd" bit counts in order to ensure full code coverage:
  92    //
  93    test<number<cpp_int_backend<528, 528, signed_magnitude, unchecked, void> > >();
  94    test<number<cpp_int_backend<528, 528, unsigned_magnitude, unchecked, void> > >();
  95    test<number<cpp_int_backend<48, 48, signed_magnitude, unchecked, void> > >();
  96    test<number<cpp_int_backend<48, 48, unsigned_magnitude, unchecked, void> > >();
  97    return boost::report_errors();
  98 }
  99
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