chromium/base/numerics/basic_ops_impl.h

// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_NUMERICS_BASIC_OPS_IMPL_H_
#define BASE_NUMERICS_BASIC_OPS_IMPL_H_

#include <array>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <span>
#include <type_traits>

namespace base::internal {

// The correct type to perform math operations on given values of type `T`. This
// may be a larger type than `T` to avoid promotion to `int` which involves sign
// conversion!
MathType;

// Reverses the byte order of the integer.
template <class T>
  requires(std::is_unsigned_v<T> && std::is_integral_v<T>)
inline constexpr T SwapBytes(T value) { … }

// Signed values are byte-swapped as unsigned values.
template <class T>
  requires(std::is_signed_v<T> && std::is_integral_v<T>)
inline constexpr T SwapBytes(T value) { … }

// Converts from a byte array to an integer.
template <class T>
  requires(std::is_unsigned_v<T> && std::is_integral_v<T>)
inline constexpr T FromLittleEndian(std::span<const uint8_t, sizeof(T)> bytes) { … }

template <class T>
  requires(std::is_signed_v<T> && std::is_integral_v<T>)
inline constexpr T FromLittleEndian(std::span<const uint8_t, sizeof(T)> bytes) { … }

// Converts to a byte array from an integer.
template <class T>
  requires(std::is_unsigned_v<T> && std::is_integral_v<T>)
inline constexpr std::array<uint8_t, sizeof(T)> ToLittleEndian(T val) { … }

template <class T>
  requires(std::is_signed_v<T> && std::is_integral_v<T>)
inline constexpr std::array<uint8_t, sizeof(T)> ToLittleEndian(T val) { … }
}  // namespace base::internal

#endif  //  BASE_NUMERICS_BASIC_OPS_IMPL_H_