serenity/AK/Endian.h

/*
 * Copyright (c) 2020, the SerenityOS developers.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include <AK/Platform.h>

namespace AK {

template<typename T>
ALWAYS_INLINE T convert_between_host_and_little_endian(T value)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
    return value;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
    if constexpr (sizeof(T) == 8)
        return __builtin_bswap64(value);
    if constexpr (sizeof(T) == 4)
        return __builtin_bswap32(value);
    if constexpr (sizeof(T) == 2)
        return __builtin_bswap16(value);
    if constexpr (sizeof(T) == 1)
        return value;
#endif
}

template<typename T>
ALWAYS_INLINE T convert_between_host_and_big_endian(T value)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
    if constexpr (sizeof(T) == 8)
        return __builtin_bswap64(value);
    if constexpr (sizeof(T) == 4)
        return __builtin_bswap32(value);
    if constexpr (sizeof(T) == 2)
        return __builtin_bswap16(value);
    if constexpr (sizeof(T) == 1)
        return value;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
    return value;
#endif
}

template<typename T>
ALWAYS_INLINE T convert_between_host_and_network_endian(T value)
{
    return convert_between_host_and_big_endian(value);
}

template<typename T>
class [[gnu::packed]] LittleEndian
{
public:
    LittleEndian() { }

    LittleEndian(T value)
        : m_value(convert_between_host_and_little_endian(value))
    {
    }

    operator T() const { return convert_between_host_and_little_endian(m_value); }

private:
    T m_value { 0 };
};

template<typename T>
class [[gnu::packed]] BigEndian
{
public:
    BigEndian() { }

    BigEndian(T value)
        : m_value(convert_between_host_and_big_endian(value))
    {
    }

    operator T() const { return convert_between_host_and_big_endian(m_value); }

private:
    T m_value { 0 };
};

template<typename T>
using NetworkOrdered = BigEndian<T>;

}

using AK::BigEndian;
using AK::LittleEndian;
using AK::NetworkOrdered;