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add c++1y rightmost bit manipurations

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bolero-MURAKAMI 2014-03-31 17:18:22 +09:00
parent 56c9d52436
commit e244ea2932
21 changed files with 560 additions and 183 deletions
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68
sprout/bit/length.hpp
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@ -8,73 +8,7 @@
#ifndef SPROUT_BIT_LENGTH_HPP
#define SPROUT_BIT_LENGTH_HPP
#include <climits>
#include <cstddef>
#include <type_traits>
#include <sprout/config.hpp>
namespace sprout {
namespace detail {
SPROUT_STATIC_CONSTEXPR std::size_t bit_len_8_table[std::size_t(UCHAR_MAX) + 1] = {
0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8
};
template<std::size_t Size>
struct bit_len {
private:
SPROUT_STATIC_CONSTEXPR std::size_t next_size = Size - 1;
SPROUT_STATIC_CONSTEXPR std::size_t shift_bits = next_size * CHAR_BIT;
private:
template<typename IntType>
SPROUT_CONSTEXPR IntType
impl(IntType x, unsigned char i) const {
return bit_len_8_table[i]
? bit_len_8_table[i] + next_size * CHAR_BIT
: sprout::detail::bit_len<next_size>().template operator()(x)
;
}
public:
template<typename IntType>
SPROUT_CONSTEXPR IntType
operator()(IntType x) const {
return impl(x, static_cast<unsigned char>((x >> shift_bits) & UCHAR_MAX));
}
};
template<>
struct bit_len<1> {
public:
template<typename IntType>
SPROUT_CONSTEXPR IntType
operator()(IntType x) const {
return bit_len_8_table[static_cast<unsigned char>(x & UCHAR_MAX)];
}
};
} // namespace detail
//
// bit_length
//
template<typename IntType>
inline SPROUT_CONSTEXPR typename std::enable_if<
std::is_integral<IntType>::value,
IntType
>::type
bit_length(IntType x) {
return sprout::detail::bit_len<sizeof(IntType)>().template operator()(x);
}
} // namespace sprout
#include <sprout/bit/bit_length.hpp>
#endif // #ifndef SPROUT_BIT_LENGTH_HPP