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fix ctz/clz bitwise operation implementation

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This commit is contained in:
bolero-MURAKAMI 2014-04-13 17:48:24 +09:00
parent fb69a146dd
commit 3e4dd5de00
3 changed files with 125 additions and 39 deletions
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77
sprout/bit/ctz.hpp
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@ -11,6 +11,10 @@
#include <climits>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/limits.hpp>
#include <sprout/detail/integer.hpp>
#include <sprout/utility/pair/pair.hpp>
#include <sprout/bit/shlr.hpp>
namespace sprout {
namespace detail {
@ -28,27 +32,70 @@ namespace sprout {
return __builtin_ctzll(x);
}
# endif
template<typename Integral>
template<std::size_t N, typename Integral>
inline SPROUT_CONSTEXPR typename std::enable_if<
std::is_unsigned<Integral>::value,
int
(N == 1),
sprout::pair<Integral, int>
>::type
ctz_non0(Integral x) {
return x & 1 ? 0
: 1 + sprout::detail::ctz_non0(static_cast<Integral>(x >> 1))
;
ctz_bytes(sprout::pair<Integral, int> const& xn) SPROUT_NOEXCEPT {
return xn;
}
template<std::size_t N, typename Integral>
inline SPROUT_CONSTEXPR typename std::enable_if<
(N > 1),
sprout::pair<Integral, int>
>::type
ctz_bytes(sprout::pair<Integral, int> const& xn) SPROUT_NOEXCEPT {
typedef sprout::pair<Integral, int> type;
return sprout::detail::ctz_bytes<N / 2>(
(xn.first & static_cast<Integral>(sprout::numeric_limits<typename sprout::detail::uint_t<N / 2 * CHAR_BIT>::least>::max())) ? xn
: type(sprout::shlr(xn.first, N / 2 * CHAR_BIT), xn.second + N / 2 * CHAR_BIT)
);
}
template<typename Integral>
inline SPROUT_CONSTEXPR typename std::enable_if<
std::is_signed<Integral>::value,
int
>::type
ctz_non0(Integral x) {
return sprout::detail::ctz_non0(static_cast<typename std::make_unsigned<Integral>::type>(x));
inline SPROUT_CONSTEXPR sprout::pair<Integral, int>
ctz_bytes(sprout::pair<Integral, int> const& xn) SPROUT_NOEXCEPT {
return sprout::detail::ctz_bytes<sizeof(Integral)>(xn);
}
template<typename Integral>
inline SPROUT_CONSTEXPR int
ctz(Integral x) {
ctz_bits1(sprout::pair<Integral, int> const& xn) SPROUT_NOEXCEPT {
return (xn.first & Integral(0x1ul)) ? xn.second
: xn.second + 1
;
}
template<typename Integral>
inline SPROUT_CONSTEXPR int
ctz_bits2(sprout::pair<Integral, int> const& xn) SPROUT_NOEXCEPT {
typedef sprout::pair<Integral, int> type;
return sprout::detail::ctz_bits1(
(xn.first & Integral(0x3ul)) ? xn
: type(sprout::shlr(xn.first, 2), xn.second + 2)
);
}
template<typename Integral>
inline SPROUT_CONSTEXPR int
ctz_bits4(sprout::pair<Integral, int> const& xn) SPROUT_NOEXCEPT {
typedef sprout::pair<Integral, int> type;
return sprout::detail::ctz_bits2(
(xn.first & Integral(0xful)) ? xn
: type(sprout::shlr(xn.first, 4), xn.second + 4)
);
}
template<typename Integral>
inline SPROUT_CONSTEXPR int
ctz_bits(sprout::pair<Integral, int> const& xn) SPROUT_NOEXCEPT {
return sprout::detail::ctz_bits4(xn);
}
template<typename Integral>
inline SPROUT_CONSTEXPR int
ctz_non0(Integral x) SPROUT_NOEXCEPT {
typedef sprout::pair<Integral, int> type;
return sprout::detail::ctz_bits(sprout::detail::ctz_bytes(type(x, 0)));
}
template<typename Integral>
inline SPROUT_CONSTEXPR int
ctz(Integral x) SPROUT_NOEXCEPT {
return x == 0 ? static_cast<int>(sizeof(x) * CHAR_BIT)
: sprout::detail::ctz_non0(x)
;
@ -62,7 +109,7 @@ namespace sprout {
std::is_integral<Integral>::value,
int
>::type
ctz(Integral x) {
ctz(Integral x) SPROUT_NOEXCEPT {
return sprout::detail::ctz(x);
}
} // namespace sprout