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487 lines
14 KiB
487 lines
14 KiB
// -*- C++ -*-
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//===------------------------------ bit ----------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===---------------------------------------------------------------------===//
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#ifndef _LIBCPP_BIT
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#define _LIBCPP_BIT
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/*
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bit synopsis
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namespace std {
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// [bit.pow.two], integral powers of 2
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template <class T>
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constexpr bool has_single_bit(T x) noexcept; // C++20
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template <class T>
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constexpr T bit_ceil(T x); // C++20
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template <class T>
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constexpr T bit_floor(T x) noexcept; // C++20
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template <class T>
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constexpr T bit_width(T x) noexcept; // C++20
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// [bit.rotate], rotating
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template<class T>
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constexpr T rotl(T x, unsigned int s) noexcept; // C++20
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template<class T>
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constexpr T rotr(T x, unsigned int s) noexcept; // C++20
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// [bit.count], counting
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template<class T>
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constexpr int countl_zero(T x) noexcept; // C++20
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template<class T>
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constexpr int countl_one(T x) noexcept; // C++20
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template<class T>
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constexpr int countr_zero(T x) noexcept; // C++20
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template<class T>
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constexpr int countr_one(T x) noexcept; // C++20
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template<class T>
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constexpr int popcount(T x) noexcept; // C++20
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// [bit.endian], endian
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enum class endian {
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little = see below, // C++20
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big = see below, // C++20
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native = see below // C++20
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};
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} // namespace std
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*/
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#include <__config>
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#include <limits>
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#include <type_traits>
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#include <version>
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#include <__debug>
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#if defined(__IBMCPP__)
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#include "support/ibm/support.h"
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#endif
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#if defined(_LIBCPP_COMPILER_MSVC)
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#include <intrin.h>
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#endif
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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#pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#ifndef _LIBCPP_COMPILER_MSVC
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_clz(unsigned __x) _NOEXCEPT { return __builtin_clz(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_clz(unsigned long __x) _NOEXCEPT { return __builtin_clzl(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_popcount(unsigned __x) _NOEXCEPT { return __builtin_popcount(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_popcount(unsigned long __x) _NOEXCEPT { return __builtin_popcountl(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }
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#else // _LIBCPP_COMPILER_MSVC
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// Precondition: __x != 0
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_ctz(unsigned __x) {
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static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
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static_assert(sizeof(unsigned long) == 4, "");
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unsigned long __where;
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if (_BitScanForward(&__where, __x))
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return static_cast<int>(__where);
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return 32;
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_ctz(unsigned long __x) {
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static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
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return __ctz(static_cast<unsigned>(__x));
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_ctz(unsigned long long __x) {
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unsigned long __where;
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#if defined(_LIBCPP_HAS_BITSCAN64)
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(defined(_M_AMD64) || defined(__x86_64__))
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if (_BitScanForward64(&__where, __x))
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return static_cast<int>(__where);
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#else
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// Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
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if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
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return static_cast<int>(__where);
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if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
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return static_cast<int>(__where + 32);
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#endif
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return 64;
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}
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// Precondition: __x != 0
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_clz(unsigned __x) {
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static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
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static_assert(sizeof(unsigned long) == 4, "");
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unsigned long __where;
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if (_BitScanReverse(&__where, __x))
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return static_cast<int>(31 - __where);
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return 32; // Undefined Behavior.
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_clz(unsigned long __x) {
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static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
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return __libcpp_clz(static_cast<unsigned>(__x));
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}
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inline _LIBCPP_INLINE_VISIBILITY
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int __libcpp_clz(unsigned long long __x) {
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unsigned long __where;
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#if defined(_LIBCPP_HAS_BITSCAN64)
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if (_BitScanReverse64(&__where, __x))
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return static_cast<int>(63 - __where);
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#else
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// Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
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if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
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return static_cast<int>(63 - (__where + 32));
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if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
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return static_cast<int>(63 - __where);
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#endif
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return 64; // Undefined Behavior.
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}
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inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) {
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static_assert(sizeof(unsigned) == 4, "");
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return __popcnt(__x);
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}
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inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) {
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static_assert(sizeof(unsigned long) == 4, "");
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return __popcnt(__x);
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}
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inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) {
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static_assert(sizeof(unsigned long long) == 8, "");
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return __popcnt64(__x);
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}
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#endif // _LIBCPP_COMPILER_MSVC
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template <class _Tp>
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using __bitop_unsigned_integer _LIBCPP_NODEBUG_TYPE = integral_constant<bool,
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is_integral<_Tp>::value &&
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is_unsigned<_Tp>::value &&
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_IsNotSame<typename remove_cv<_Tp>::type, bool>::value &&
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_IsNotSame<typename remove_cv<_Tp>::type, signed char>::value &&
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_IsNotSame<typename remove_cv<_Tp>::type, wchar_t>::value &&
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_IsNotSame<typename remove_cv<_Tp>::type, char16_t>::value &&
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_IsNotSame<typename remove_cv<_Tp>::type, char32_t>::value
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>;
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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_Tp __rotl(_Tp __t, unsigned int __cnt) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotl requires unsigned");
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const unsigned int __dig = numeric_limits<_Tp>::digits;
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if ((__cnt % __dig) == 0)
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return __t;
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return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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_Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotr requires unsigned");
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const unsigned int __dig = numeric_limits<_Tp>::digits;
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if ((__cnt % __dig) == 0)
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return __t;
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return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig)));
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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int __countr_zero(_Tp __t) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_zero requires unsigned");
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if (__t == 0)
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return numeric_limits<_Tp>::digits;
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if (sizeof(_Tp) <= sizeof(unsigned int))
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return __libcpp_ctz(static_cast<unsigned int>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long))
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return __libcpp_ctz(static_cast<unsigned long>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long long))
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return __libcpp_ctz(static_cast<unsigned long long>(__t));
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else
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{
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int __ret = 0;
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int __iter = 0;
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const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
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while ((__iter = __libcpp_ctz(static_cast<unsigned long long>(__t))) == __ulldigits)
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{
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__ret += __iter;
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__t >>= __ulldigits;
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}
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return __ret + __iter;
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}
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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int __countl_zero(_Tp __t) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_zero requires unsigned");
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if (__t == 0)
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return numeric_limits<_Tp>::digits;
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if (sizeof(_Tp) <= sizeof(unsigned int))
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return __libcpp_clz(static_cast<unsigned int>(__t))
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- (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits);
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else if (sizeof(_Tp) <= sizeof(unsigned long))
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return __libcpp_clz(static_cast<unsigned long>(__t))
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- (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits);
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else if (sizeof(_Tp) <= sizeof(unsigned long long))
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return __libcpp_clz(static_cast<unsigned long long>(__t))
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- (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits);
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else
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{
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int __ret = 0;
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int __iter = 0;
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const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
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while (true) {
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__t = __rotr(__t, __ulldigits);
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if ((__iter = __countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits)
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break;
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__ret += __iter;
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}
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return __ret + __iter;
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}
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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int __countl_one(_Tp __t) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_one requires unsigned");
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return __t != numeric_limits<_Tp>::max()
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? __countl_zero(static_cast<_Tp>(~__t))
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: numeric_limits<_Tp>::digits;
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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int __countr_one(_Tp __t) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_one requires unsigned");
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return __t != numeric_limits<_Tp>::max()
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? __countr_zero(static_cast<_Tp>(~__t))
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: numeric_limits<_Tp>::digits;
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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int
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__popcount(_Tp __t) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__libcpp_popcount requires unsigned");
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if (sizeof(_Tp) <= sizeof(unsigned int))
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return __libcpp_popcount(static_cast<unsigned int>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long))
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return __libcpp_popcount(static_cast<unsigned long>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long long))
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return __libcpp_popcount(static_cast<unsigned long long>(__t));
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else
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{
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int __ret = 0;
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while (__t != 0)
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{
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__ret += __libcpp_popcount(static_cast<unsigned long long>(__t));
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__t >>= numeric_limits<unsigned long long>::digits;
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}
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return __ret;
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}
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}
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// integral log base 2
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
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unsigned __bit_log2(_Tp __t) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__bit_log2 requires unsigned");
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return numeric_limits<_Tp>::digits - 1 - __countl_zero(__t);
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}
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template <class _Tp>
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_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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bool __has_single_bit(_Tp __t) _NOEXCEPT
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{
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static_assert(__bitop_unsigned_integer<_Tp>::value, "__has_single_bit requires unsigned");
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return __t != 0 && (((__t & (__t - 1)) == 0));
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}
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#if _LIBCPP_STD_VER > 17
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
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rotl(_Tp __t, unsigned int __cnt) noexcept
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{
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return __rotl(__t, __cnt);
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}
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// rotr
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
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rotr(_Tp __t, unsigned int __cnt) noexcept
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{
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return __rotr(__t, __cnt);
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
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countl_zero(_Tp __t) noexcept
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{
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return __countl_zero(__t);
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
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countl_one(_Tp __t) noexcept
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{
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return __countl_one(__t);
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
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countr_zero(_Tp __t) noexcept
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{
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return __countr_zero(__t);
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
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countr_one(_Tp __t) noexcept
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{
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return __countr_one(__t);
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}
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template<class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
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popcount(_Tp __t) noexcept
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{
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return __popcount(__t);
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}
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template <class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, bool>
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has_single_bit(_Tp __t) noexcept
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{
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return __has_single_bit(__t);
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}
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template <class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
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bit_floor(_Tp __t) noexcept
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{
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return __t == 0 ? 0 : _Tp{1} << __bit_log2(__t);
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}
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template <class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
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bit_ceil(_Tp __t) noexcept
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{
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if (__t < 2) return 1;
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const unsigned __n = numeric_limits<_Tp>::digits - countl_zero((_Tp)(__t - 1u));
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_LIBCPP_DEBUG_ASSERT(__libcpp_is_constant_evaluated() || __n != numeric_limits<_Tp>::digits, "Bad input to bit_ceil");
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if constexpr (sizeof(_Tp) >= sizeof(unsigned))
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return _Tp{1} << __n;
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else
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{
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const unsigned __extra = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits;
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const unsigned __retVal = 1u << (__n + __extra);
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return (_Tp) (__retVal >> __extra);
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}
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}
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template <class _Tp>
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_LIBCPP_INLINE_VISIBILITY constexpr
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enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
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bit_width(_Tp __t) noexcept
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{
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return __t == 0 ? 0 : __bit_log2(__t) + 1;
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}
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enum class endian
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{
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little = 0xDEAD,
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big = 0xFACE,
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#if defined(_LIBCPP_LITTLE_ENDIAN)
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native = little
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#elif defined(_LIBCPP_BIG_ENDIAN)
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native = big
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#else
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native = 0xCAFE
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#endif
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};
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#endif // _LIBCPP_STD_VER > 17
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP_BIT
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