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- ///////////////////////////////////////////////////////////////
- // Copyright 2017 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
- //
- // Check results of truncated overflow.
- //
- #ifdef _MSC_VER
- #define _SCL_SECURE_NO_WARNINGS
- #endif
- #include <boost/multiprecision/cpp_int.hpp>
- #include "test.hpp"
- #include <boost/random/mersenne_twister.hpp>
- #include <boost/random/uniform_int.hpp>
- 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 Number>
- void test()
- {
- using namespace boost::multiprecision;
- typedef Number test_type;
- for (unsigned i = 30; i < std::numeric_limits<test_type>::digits; ++i)
- {
- for (unsigned j = std::numeric_limits<test_type>::digits - i - 1; j < std::numeric_limits<test_type>::digits; ++j)
- {
- for (unsigned k = 0; k < 10; ++k)
- {
- test_type a = static_cast<test_type>(generate_random<cpp_int>(i));
- test_type b = static_cast<test_type>(generate_random<cpp_int>(j));
- test_type c = static_cast<test_type>(cpp_int(a) * cpp_int(b));
- test_type d = a * b;
- BOOST_CHECK_EQUAL(c, d);
- if ((k == 0) && (j == 0))
- {
- for (unsigned s = 1; s < std::numeric_limits<test_type>::digits; ++s)
- BOOST_CHECK_EQUAL(a << s, test_type(cpp_int(a) << s));
- }
- }
- }
- }
- }
- int main()
- {
- using namespace boost::multiprecision;
- test<int512_t>();
- test<uint512_t>();
- //
- // We also need to test type with "odd" bit counts in order to ensure full code coverage:
- //
- test<number<cpp_int_backend<528, 528, signed_magnitude, unchecked, void> > >();
- test<number<cpp_int_backend<528, 528, unsigned_magnitude, unchecked, void> > >();
- test<number<cpp_int_backend<48, 48, signed_magnitude, unchecked, void> > >();
- test<number<cpp_int_backend<48, 48, unsigned_magnitude, unchecked, void> > >();
- return boost::report_errors();
- }
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