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/Forward.h>
#include <AK/Platform.h>

#if defined(AK_OS_MACOS)
#    include <libkern/OSByteOrder.h>
#    include <machine/endian.h>

#    define htobe16(x) OSSwapHostToBigInt16(x)
#    define htole16(x) OSSwapHostToLittleInt16(x)
#    define be16toh(x) OSSwapBigToHostInt16(x)
#    define le16toh(x) OSSwapLittleToHostInt16(x)

#    define htobe32(x) OSSwapHostToBigInt32(x)
#    define htole32(x) OSSwapHostToLittleInt32(x)
#    define be32toh(x) OSSwapBigToHostInt32(x)
#    define le32toh(x) OSSwapLittleToHostInt32(x)

#    define htobe64(x) OSSwapHostToBigInt64(x)
#    define htole64(x) OSSwapHostToLittleInt64(x)
#    define be64toh(x) OSSwapBigToHostInt64(x)
#    define le64toh(x) OSSwapLittleToHostInt64(x)

#    define __BIG_ENDIAN BIG_ENDIAN
#    define __LITTLE_ENDIAN LITTLE_ENDIAN
#    define __BYTE_ORDER BYTE_ORDER
#endif

namespace AK {

template<typename T>
ALWAYS_INLINE constexpr 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 constexpr 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 LittleEndian;

template<typename T>
InputStream& operator>>(InputStream&, LittleEndian<T>&);

template<typename T>
OutputStream& operator<<(OutputStream&, LittleEndian<T>);

template<typename T>
class [[gnu::packed]] LittleEndian
{
public:
    friend InputStream& operator>><T>(InputStream&, LittleEndian<T>&);
    friend OutputStream& operator<<<T>(OutputStream&, LittleEndian<T>);

    constexpr LittleEndian() { }

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

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

private:
    T m_value { 0 };
};

template<typename T>
class BigEndian;

template<typename T>
InputStream& operator>>(InputStream&, BigEndian<T>&);

template<typename T>
OutputStream& operator<<(OutputStream&, BigEndian<T>);

template<typename T>
class [[gnu::packed]] BigEndian
{
public:
    friend InputStream& operator>><T>(InputStream&, BigEndian<T>&);
    friend OutputStream& operator<<<T>(OutputStream&, BigEndian<T>);

    constexpr BigEndian() = default;

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

    constexpr 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;