| // Test for boost/core/bit.hpp (bit_width) |
| // |
| // Copyright 2020 Peter Dimov |
| // Distributed under the Boost Software License, Version 1.0. |
| // https://www.boost.org/LICENSE_1_0.txt |
| |
| #include <boost/core/bit.hpp> |
| #include <boost/core/lightweight_test.hpp> |
| #include <boost/core/detail/splitmix64.hpp> |
| #include <boost/cstdint.hpp> |
| #include <limits> |
| |
| template<class T> void test_width( T x ) |
| { |
| BOOST_TEST_EQ( boost::core::bit_width( x ), std::numeric_limits<T>::digits - boost::core::countl_zero( x ) ); |
| } |
| |
| int main() |
| { |
| { |
| boost::uint8_t x = 0; |
| |
| BOOST_TEST_EQ( boost::core::bit_width( x ), 0 ); |
| |
| x = 1; |
| |
| for( int i = 0; i < 8; ++i, x <<= 1 ) |
| { |
| BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint8_t>( x | ( x >> 1 ) ) ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint8_t>( x | ( x >> 2 ) ) ), i+1 ); |
| } |
| } |
| |
| { |
| boost::uint16_t x = 0; |
| |
| BOOST_TEST_EQ( boost::core::bit_width( x ), 0 ); |
| |
| x = 1; |
| |
| for( int i = 0; i < 16; ++i, x <<= 1 ) |
| { |
| BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint16_t>( x | ( x >> 1 ) ) ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint16_t>( x | ( x >> 2 ) ) ), i+1 ); |
| } |
| } |
| |
| { |
| boost::uint32_t x = 0; |
| |
| BOOST_TEST_EQ( boost::core::bit_width( x ), 0 ); |
| |
| x = 1; |
| |
| for( int i = 0; i < 32; ++i, x <<= 1 ) |
| { |
| BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint32_t>( x | ( x >> 1 ) ) ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint32_t>( x | ( x >> 2 ) ) ), i+1 ); |
| } |
| } |
| |
| { |
| boost::uint64_t x = 0; |
| |
| BOOST_TEST_EQ( boost::core::bit_width( x ), 0 ); |
| |
| x = 1; |
| |
| for( int i = 0; i < 64; ++i, x <<= 1 ) |
| { |
| BOOST_TEST_EQ( boost::core::bit_width( x ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint64_t>( x | ( x >> 1 ) ) ), i+1 ); |
| BOOST_TEST_EQ( boost::core::bit_width( static_cast<boost::uint64_t>( x | ( x >> 2 ) ) ), i+1 ); |
| } |
| } |
| |
| boost::detail::splitmix64 rng; |
| |
| for( int i = 0; i < 1000; ++i ) |
| { |
| boost::uint64_t x = rng(); |
| |
| test_width( static_cast<unsigned char>( x ) ); |
| test_width( static_cast<unsigned short>( x ) ); |
| test_width( static_cast<unsigned int>( x ) ); |
| test_width( static_cast<unsigned long>( x ) ); |
| test_width( static_cast<unsigned long long>( x ) ); |
| } |
| |
| return boost::report_errors(); |
| } |