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

   1 ///////////////////////////////////////////////////////////////
   2 //  Copyright 2012 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 // Compare results of truncated left shift to gmp, see:
   8 // https://svn.boost.org/trac/boost/ticket/12790
   9 //
  10
  11 #ifdef _MSC_VER
  12 #define _SCL_SECURE_NO_WARNINGS
  13 #endif
  14
  15 #include <boost/multiprecision/gmp.hpp>
  16 #include <boost/multiprecision/cpp_int.hpp>
  17 #include <boost/random/mersenne_twister.hpp>
  18 #include <boost/random/uniform_int.hpp>
  19 #include "test.hpp"
  20
  21 #if !defined(TEST1) && !defined(TEST2) && !defined(TEST3)
  22 #define TEST1
  23 #define TEST2
  24 #define TEST3
  25 #endif
  26
  27 template <class T>
  28 T generate_random(unsigned bits_wanted)
  29 {
  30    static boost::random::mt19937               gen;
  31    typedef boost::random::mt19937::result_type random_type;
  32
  33    T        max_val;
  34    unsigned digits;
  35    if (std::numeric_limits<T>::is_bounded && (bits_wanted == (unsigned)std::numeric_limits<T>::digits))
  36    {
  37       max_val = (std::numeric_limits<T>::max)();
  38       digits  = std::numeric_limits<T>::digits;
  39    }
  40    else
  41    {
  42       max_val = T(1) << bits_wanted;
  43       digits  = bits_wanted;
  44    }
  45
  46    unsigned bits_per_r_val = std::numeric_limits<random_type>::digits - 1;
  47    while ((random_type(1) << bits_per_r_val) > (gen.max)())
  48       --bits_per_r_val;
  49
  50    unsigned terms_needed = digits / bits_per_r_val + 1;
  51
  52    T val = 0;
  53    for (unsigned i = 0; i < terms_needed; ++i)
  54    {
  55       val *= (gen.max)();
  56       val += gen();
  57    }
  58    val %= max_val;
  59    return val;
  60 }
  61
  62 template <class T>
  63 void test_value(const T& val)
  64 {
  65    boost::multiprecision::mpz_int z(val.str()), mask(1);
  66    mask <<= std::numeric_limits<T>::digits;
  67    --mask;
  68
  69    for (unsigned i = 0; i <= std::numeric_limits<T>::digits + 2; ++i)
  70    {
  71       BOOST_CHECK_EQUAL((val << i).str(), boost::multiprecision::mpz_int(((z << i) & mask)).str());
  72    }
  73 }
  74
  75 void test(const boost::mpl::int_<200>&) {}
  76
  77 template <int N>
  78 void test(boost::mpl::int_<N> const&)
  79 {
  80    test(boost::mpl::int_<N + 4>());
  81
  82    typedef boost::multiprecision::number<boost::multiprecision::cpp_int_backend<N, N, boost::multiprecision::unsigned_magnitude>, boost::multiprecision::et_off> mp_type;
  83
  84    std::cout << "Running tests for precision: " << N << std::endl;
  85
  86    mp_type mp(-1);
  87    test_value(mp);
  88
  89    for (unsigned i = 0; i < 1000; ++i)
  90       test_value(generate_random<mp_type>(std::numeric_limits<mp_type>::digits));
  91 }
  92
  93 int main()
  94 {
  95    test(boost::mpl::int_<24>());
  96    return boost::report_errors();
  97 }