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