chromium/third_party/abseil-cpp/absl/numeric/internal/bits.h

// Copyright 2020 The Abseil Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ABSL_NUMERIC_INTERNAL_BITS_H_
#define ABSL_NUMERIC_INTERNAL_BITS_H_

#include <cstdint>
#include <limits>
#include <type_traits>

// Clang on Windows has __builtin_clzll; otherwise we need to use the
// windows intrinsic functions.
#if defined(_MSC_VER) && !defined(__clang__)
#include <intrin.h>
#endif

#include "absl/base/attributes.h"
#include "absl/base/config.h"

#if defined(__GNUC__) && !defined(__clang__)
// GCC
#define ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC …
#else
#define ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(x) …
#endif

#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_popcountl) && \
    ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_popcountll)
#define ABSL_INTERNAL_CONSTEXPR_POPCOUNT …
#define ABSL_INTERNAL_HAS_CONSTEXPR_POPCOUNT …
#else
#define ABSL_INTERNAL_CONSTEXPR_POPCOUNT
#define ABSL_INTERNAL_HAS_CONSTEXPR_POPCOUNT …
#endif

#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_clz) && \
    ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_clzll)
#define ABSL_INTERNAL_CONSTEXPR_CLZ …
#define ABSL_INTERNAL_HAS_CONSTEXPR_CLZ …
#else
#define ABSL_INTERNAL_CONSTEXPR_CLZ
#define ABSL_INTERNAL_HAS_CONSTEXPR_CLZ …
#endif

#if ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_ctz) && \
    ABSL_NUMERIC_INTERNAL_HAVE_BUILTIN_OR_GCC(__builtin_ctzll)
#define ABSL_INTERNAL_CONSTEXPR_CTZ …
#define ABSL_INTERNAL_HAS_CONSTEXPR_CTZ …
#else
#define ABSL_INTERNAL_CONSTEXPR_CTZ
#define ABSL_INTERNAL_HAS_CONSTEXPR_CTZ …
#endif

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace numeric_internal {

constexpr bool IsPowerOf2(unsigned int x) noexcept { … }

template <class T>
ABSL_MUST_USE_RESULT ABSL_ATTRIBUTE_ALWAYS_INLINE constexpr T RotateRight(
    T x, int s) noexcept { … }

template <class T>
ABSL_MUST_USE_RESULT ABSL_ATTRIBUTE_ALWAYS_INLINE constexpr T RotateLeft(
    T x, int s) noexcept { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline int
Popcount32(uint32_t x) noexcept { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline int
Popcount64(uint64_t x) noexcept { … }

template <class T>
ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline int
Popcount(T x) noexcept { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline int
CountLeadingZeroes32(uint32_t x) { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline int
CountLeadingZeroes16(uint16_t x) { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline int
CountLeadingZeroes64(uint64_t x) { … }

template <typename T>
ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline int
CountLeadingZeroes(T x) { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CTZ inline int
CountTrailingZeroesNonzero32(uint32_t x) { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CTZ inline int
CountTrailingZeroesNonzero64(uint64_t x) { … }

ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CTZ inline int
CountTrailingZeroesNonzero16(uint16_t x) { … }

template <class T>
ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CTZ inline int
CountTrailingZeroes(T x) noexcept { … }

// If T is narrower than unsigned, T{1} << bit_width will be promoted.  We
// want to force it to wraparound so that bit_ceil of an invalid value are not
// core constant expressions.
template <class T>
ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline
    typename std::enable_if<std::is_unsigned<T>::value, T>::type
    BitCeilPromotionHelper(T x, T promotion) { … }

template <class T>
ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_CLZ inline
    typename std::enable_if<std::is_unsigned<T>::value, T>::type
    BitCeilNonPowerOf2(T x) { … }

}  // namespace numeric_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_NUMERIC_INTERNAL_BITS_H_