zig/lib/libcxx/include/bit

466 lines
14 KiB
C++

// -*- C++ -*-
//===------------------------------ bit ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===---------------------------------------------------------------------===//
#ifndef _LIBCPP_BIT
#define _LIBCPP_BIT
/*
bit synopsis
namespace std {
template <class T>
constexpr bool ispow2(T x) noexcept; // C++20
template <class T>
constexpr T ceil2(T x); // C++20
template <class T>
constexpr T floor2(T x) noexcept; // C++20
template <class T>
constexpr T log2p1(T x) noexcept; // C++20
// 23.20.2, rotating
template<class T>
constexpr T rotl(T x, unsigned int s) noexcept; // C++20
template<class T>
constexpr T rotr(T x, unsigned int s) noexcept; // C++20
// 23.20.3, counting
template<class T>
constexpr int countl_zero(T x) noexcept; // C++20
template<class T>
constexpr int countl_one(T x) noexcept; // C++20
template<class T>
constexpr int countr_zero(T x) noexcept; // C++20
template<class T>
constexpr int countr_one(T x) noexcept; // C++20
template<class T>
constexpr int popcount(T x) noexcept; // C++20
} // namespace std
*/
#include <__config>
#include <limits>
#include <type_traits>
#include <version>
#include <__debug>
#if defined(__IBMCPP__)
#include "support/ibm/support.h"
#endif
#if defined(_LIBCPP_COMPILER_MSVC)
#include <intrin.h>
#endif
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#ifndef _LIBCPP_COMPILER_MSVC
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_clz(unsigned __x) _NOEXCEPT { return __builtin_clz(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_clz(unsigned long __x) _NOEXCEPT { return __builtin_clzl(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_popcount(unsigned __x) _NOEXCEPT { return __builtin_popcount(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_popcount(unsigned long __x) _NOEXCEPT { return __builtin_popcountl(__x); }
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }
#else // _LIBCPP_COMPILER_MSVC
// Precondition: __x != 0
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_ctz(unsigned __x) {
static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
static_assert(sizeof(unsigned long) == 4, "");
unsigned long __where;
if (_BitScanForward(&__where, __x))
return static_cast<int>(__where);
return 32;
}
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_ctz(unsigned long __x) {
static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
return __ctz(static_cast<unsigned>(__x));
}
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_ctz(unsigned long long __x) {
unsigned long __where;
#if defined(_LIBCPP_HAS_BITSCAN64)
(defined(_M_AMD64) || defined(__x86_64__))
if (_BitScanForward64(&__where, __x))
return static_cast<int>(__where);
#else
// Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
return static_cast<int>(__where);
if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
return static_cast<int>(__where + 32);
#endif
return 64;
}
// Precondition: __x != 0
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_clz(unsigned __x) {
static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
static_assert(sizeof(unsigned long) == 4, "");
unsigned long __where;
if (_BitScanReverse(&__where, __x))
return static_cast<int>(31 - __where);
return 32; // Undefined Behavior.
}
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_clz(unsigned long __x) {
static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
return __libcpp_clz(static_cast<unsigned>(__x));
}
inline _LIBCPP_INLINE_VISIBILITY
int __libcpp_clz(unsigned long long __x) {
unsigned long __where;
#if defined(_LIBCPP_HAS_BITSCAN64)
if (_BitScanReverse64(&__where, __x))
return static_cast<int>(63 - __where);
#else
// Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
return static_cast<int>(63 - (__where + 32));
if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
return static_cast<int>(63 - __where);
#endif
return 64; // Undefined Behavior.
}
inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) {
static_assert(sizeof(unsigned) == 4, "");
return __popcnt(__x);
}
inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) {
static_assert(sizeof(unsigned long) == 4, "");
return __popcnt(__x);
}
inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) {
static_assert(sizeof(unsigned long long) == 8, "");
return __popcnt64(__x);
}
#endif // _LIBCPP_COMPILER_MSVC
template <class _Tp>
using __bitop_unsigned_integer _LIBCPP_NODEBUG_TYPE = integral_constant<bool,
is_integral<_Tp>::value &&
is_unsigned<_Tp>::value &&
_IsNotSame<typename remove_cv<_Tp>::type, bool>::value &&
_IsNotSame<typename remove_cv<_Tp>::type, signed char>::value &&
_IsNotSame<typename remove_cv<_Tp>::type, wchar_t>::value &&
_IsNotSame<typename remove_cv<_Tp>::type, char16_t>::value &&
_IsNotSame<typename remove_cv<_Tp>::type, char32_t>::value
>;
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp __rotl(_Tp __t, unsigned int __cnt) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotl requires unsigned");
const unsigned int __dig = numeric_limits<_Tp>::digits;
if ((__cnt % __dig) == 0)
return __t;
return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotr requires unsigned");
const unsigned int __dig = numeric_limits<_Tp>::digits;
if ((__cnt % __dig) == 0)
return __t;
return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig)));
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countr_zero(_Tp __t) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_zero requires unsigned");
if (__t == 0)
return numeric_limits<_Tp>::digits;
if (sizeof(_Tp) <= sizeof(unsigned int))
return __libcpp_ctz(static_cast<unsigned int>(__t));
else if (sizeof(_Tp) <= sizeof(unsigned long))
return __libcpp_ctz(static_cast<unsigned long>(__t));
else if (sizeof(_Tp) <= sizeof(unsigned long long))
return __libcpp_ctz(static_cast<unsigned long long>(__t));
else
{
int __ret = 0;
int __iter = 0;
const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
while ((__iter = __libcpp_ctz(static_cast<unsigned long long>(__t))) == __ulldigits)
{
__ret += __iter;
__t >>= __ulldigits;
}
return __ret + __iter;
}
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countl_zero(_Tp __t) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_zero requires unsigned");
if (__t == 0)
return numeric_limits<_Tp>::digits;
if (sizeof(_Tp) <= sizeof(unsigned int))
return __libcpp_clz(static_cast<unsigned int>(__t))
- (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits);
else if (sizeof(_Tp) <= sizeof(unsigned long))
return __libcpp_clz(static_cast<unsigned long>(__t))
- (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits);
else if (sizeof(_Tp) <= sizeof(unsigned long long))
return __libcpp_clz(static_cast<unsigned long long>(__t))
- (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits);
else
{
int __ret = 0;
int __iter = 0;
const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
while (true) {
__t = __rotr(__t, __ulldigits);
if ((__iter = __countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits)
break;
__ret += __iter;
}
return __ret + __iter;
}
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countl_one(_Tp __t) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_one requires unsigned");
return __t != numeric_limits<_Tp>::max()
? __countl_zero(static_cast<_Tp>(~__t))
: numeric_limits<_Tp>::digits;
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int __countr_one(_Tp __t) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_one requires unsigned");
return __t != numeric_limits<_Tp>::max()
? __countr_zero(static_cast<_Tp>(~__t))
: numeric_limits<_Tp>::digits;
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
int
__popcount(_Tp __t) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__libcpp_popcount requires unsigned");
if (sizeof(_Tp) <= sizeof(unsigned int))
return __libcpp_popcount(static_cast<unsigned int>(__t));
else if (sizeof(_Tp) <= sizeof(unsigned long))
return __libcpp_popcount(static_cast<unsigned long>(__t));
else if (sizeof(_Tp) <= sizeof(unsigned long long))
return __libcpp_popcount(static_cast<unsigned long long>(__t));
else
{
int __ret = 0;
while (__t != 0)
{
__ret += __libcpp_popcount(static_cast<unsigned long long>(__t));
__t >>= numeric_limits<unsigned long long>::digits;
}
return __ret;
}
}
// integral log base 2
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
unsigned __bit_log2(_Tp __t) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__bit_log2 requires unsigned");
return std::numeric_limits<_Tp>::digits - 1 - __countl_zero(__t);
}
template <class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
bool __ispow2(_Tp __t) _NOEXCEPT
{
static_assert(__bitop_unsigned_integer<_Tp>::value, "__ispow2 requires unsigned");
return __t != 0 && (((__t & (__t - 1)) == 0));
}
#if _LIBCPP_STD_VER > 17
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
rotl(_Tp __t, unsigned int __cnt) noexcept
{
return __rotl(__t, __cnt);
}
// rotr
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
rotr(_Tp __t, unsigned int __cnt) noexcept
{
return __rotr(__t, __cnt);
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countl_zero(_Tp __t) noexcept
{
return __countl_zero(__t);
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countl_one(_Tp __t) noexcept
{
return __countl_one(__t);
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countr_zero(_Tp __t) noexcept
{
return __countr_zero(__t);
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
countr_one(_Tp __t) noexcept
{
return __countr_one(__t);
}
template<class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, int>
popcount(_Tp __t) noexcept
{
return __popcount(__t);
}
template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, bool>
ispow2(_Tp __t) noexcept
{
return __ispow2(__t);
}
template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
floor2(_Tp __t) noexcept
{
return __t == 0 ? 0 : _Tp{1} << __bit_log2(__t);
}
template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
ceil2(_Tp __t) noexcept
{
if (__t < 2) return 1;
const unsigned __n = numeric_limits<_Tp>::digits - countl_zero((_Tp)(__t - 1u));
_LIBCPP_DEBUG_ASSERT(__libcpp_is_constant_evaluated() || __n != numeric_limits<_Tp>::digits, "Bad input to ceil2");
if constexpr (sizeof(_Tp) >= sizeof(unsigned))
return _Tp{1} << __n;
else
{
const unsigned __extra = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits;
const unsigned __retVal = 1u << (__n + __extra);
return (_Tp) (__retVal >> __extra);
}
}
template <class _Tp>
_LIBCPP_INLINE_VISIBILITY constexpr
enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp>
log2p1(_Tp __t) noexcept
{
return __t == 0 ? 0 : __bit_log2(__t) + 1;
}
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP_BIT