multiprecision/test/test_cpp_int_left_shift.cpp

99 lines
2.5 KiB
C++

///////////////////////////////////////////////////////////////
// Copyright 2012 John Maddock. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
//
// Compare results of truncated left shift to gmp, see:
// https://svn.boost.org/trac/boost/ticket/12790
//
#ifdef _MSC_VER
#define _SCL_SECURE_NO_WARNINGS
#endif
#include <boost/multiprecision/gmp.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/random/mersenne_twister.hpp>
#include <boost/random/uniform_int.hpp>
#include <boost/timer.hpp>
#include "test.hpp"
#if !defined(TEST1) && !defined(TEST2) && !defined(TEST3)
#define TEST1
#define TEST2
#define TEST3
#endif
template <class T>
T generate_random(unsigned bits_wanted)
{
static boost::random::mt19937 gen;
typedef boost::random::mt19937::result_type random_type;
T max_val;
unsigned digits;
if (std::numeric_limits<T>::is_bounded && (bits_wanted == (unsigned)std::numeric_limits<T>::digits))
{
max_val = (std::numeric_limits<T>::max)();
digits = std::numeric_limits<T>::digits;
}
else
{
max_val = T(1) << bits_wanted;
digits = bits_wanted;
}
unsigned bits_per_r_val = std::numeric_limits<random_type>::digits - 1;
while ((random_type(1) << bits_per_r_val) > (gen.max)())
--bits_per_r_val;
unsigned terms_needed = digits / bits_per_r_val + 1;
T val = 0;
for (unsigned i = 0; i < terms_needed; ++i)
{
val *= (gen.max)();
val += gen();
}
val %= max_val;
return val;
}
template <class T>
void test_value(const T& val)
{
boost::multiprecision::mpz_int z(val.str()), mask(1);
mask <<= std::numeric_limits<T>::digits;
--mask;
for (unsigned i = 0; i <= std::numeric_limits<T>::digits + 2; ++i)
{
BOOST_CHECK_EQUAL((val << i).str(), boost::multiprecision::mpz_int(((z << i) & mask)).str());
}
}
void test(const boost::mpl::int_<200>&) {}
template <int N>
void test(boost::mpl::int_<N> const&)
{
test(boost::mpl::int_<N + 4>());
typedef boost::multiprecision::number<boost::multiprecision::cpp_int_backend<N, N, boost::multiprecision::unsigned_magnitude>, boost::multiprecision::et_off> mp_type;
std::cout << "Running tests for precision: " << N << std::endl;
mp_type mp(-1);
test_value(mp);
for (unsigned i = 0; i < 1000; ++i)
test_value(generate_random<mp_type>(std::numeric_limits<mp_type>::digits));
}
int main()
{
test(boost::mpl::int_<24>());
return boost::report_errors();
}