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 <boost/timer.hpp>
  20 #include "test.hpp"
  21
  22 #if !defined(TEST1) && !defined(TEST2) && !defined(TEST3)
  23 #define TEST1
  24 #define TEST2
  25 #define TEST3
  26 #endif
  27
  28 template <class T>
  29 T generate_random(unsigned bits_wanted)
  30 {
  31    static boost::random::mt19937               gen;
  32    typedef boost::random::mt19937::result_type random_type;
  33
  34    T        max_val;
  35    unsigned digits;
  36    if (std::numeric_limits<T>::is_bounded && (bits_wanted == (unsigned)std::numeric_limits<T>::digits))
  37    {
  38       max_val = (std::numeric_limits<T>::max)();
  39       digits  = std::numeric_limits<T>::digits;
  40    }
  41    else
  42    {
  43       max_val = T(1) << bits_wanted;
  44       digits  = bits_wanted;
  45    }
  46
  47    unsigned bits_per_r_val = std::numeric_limits<random_type>::digits - 1;
  48    while ((random_type(1) << bits_per_r_val) > (gen.max)())
  49       --bits_per_r_val;
  50
  51    unsigned terms_needed = digits / bits_per_r_val + 1;
  52
  53    T val = 0;
  54    for (unsigned i = 0; i < terms_needed; ++i)
  55    {
  56       val *= (gen.max)();
  57       val += gen();
  58    }
  59    val %= max_val;
  60    return val;
  61 }
  62
  63 template <class T>
  64 void test_value(const T& val)
  65 {
  66    boost::multiprecision::mpz_int z(val.str()), mask(1);
  67    mask <<= std::numeric_limits<T>::digits;
  68    --mask;
  69
  70    for (unsigned i = 0; i <= std::numeric_limits<T>::digits + 2; ++i)
  71    {
  72       BOOST_CHECK_EQUAL((val << i).str(), boost::multiprecision::mpz_int(((z << i) & mask)).str());
  73    }
  74 }
  75
  76 void test(const boost::mpl::int_<200>&) {}
  77
  78 template <int N>
  79 void test(boost::mpl::int_<N> const&)
  80 {
  81    test(boost::mpl::int_<N + 4>());
  82
  83    typedef boost::multiprecision::number<boost::multiprecision::cpp_int_backend<N, N, boost::multiprecision::unsigned_magnitude>, boost::multiprecision::et_off> mp_type;
  84
  85    std::cout << "Running tests for precision: " << N << std::endl;
  86
  87    mp_type mp(-1);
  88    test_value(mp);
  89
  90    for (unsigned i = 0; i < 1000; ++i)
  91       test_value(generate_random<mp_type>(std::numeric_limits<mp_type>::digits));
  92 }
  93
  94 int main()
  95 {
  96    test(boost::mpl::int_<24>());
  97    return boost::report_errors();
  98 }