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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// 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___BITS
#define _LIBCPP___BITS
#include <__config>
#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); }
# ifndef _LIBCPP_HAS_NO_INT128
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
int __libcpp_clz(__uint128_t __x) _NOEXCEPT {
// The function is written in this form due to C++ constexpr limitations.
// The algorithm:
// - Test whether any bit in the high 64-bits is set
// - No bits set:
// - The high 64-bits contain 64 leading zeros,
// - Add the result of the low 64-bits.
// - Any bits set:
// - The number of leading zeros of the input is the number of leading
// zeros in the high 64-bits.
return ((__x >> 64) == 0)
? (64 + __builtin_clzll(static_cast<unsigned long long>(__x)))
: __builtin_clzll(static_cast<unsigned long long>(__x >> 64));
}
# endif
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)
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
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___BITS
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