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