endian.hpp

/*
    SPDX-License-Identifier: MIT
    Copyright © 2023-2024 Amebis
*/
 
#pragma once
 
#include "compat.hpp"
#include "system.hpp"
#include <stdint.h>
 
#ifndef LITTLE_ENDIAN
#define LITTLE_ENDIAN 1234
#endif
#ifndef BIG_ENDIAN
#define BIG_ENDIAN    4321
#endif
#ifndef BYTE_ORDER
#if defined(_WIN32)
#if REG_DWORD == REG_DWORD_LITTLE_ENDIAN
#define BYTE_ORDER    LITTLE_ENDIAN
#elif REG_DWORD == REG_DWORD_BIG_ENDIAN
#define BYTE_ORDER    BIG_ENDIAN
#endif
#elif defined(__APPLE__)
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define BYTE_ORDER    LITTLE_ENDIAN
#elif __BYTE_ORDER == __ORDER_BIG_ENDIAN__
#define BYTE_ORDER    BIG_ENDIAN
#endif
#else
#include <endian.h>
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define BYTE_ORDER    LITTLE_ENDIAN
#elif __BYTE_ORDER == __BIG_ENDIAN
#define BYTE_ORDER    BIG_ENDIAN
#endif
#endif
#ifndef BYTE_ORDER
#error Unknown endian
#endif
#endif
 
namespace stdex
{
    inline constexpr uint8_t byteswap(_In_ const uint8_t value)
    {
        return value;
    }
 
    inline uint16_t byteswap(_In_ const uint16_t value)
    {
#if _MSC_VER >= 1300
        return _byteswap_ushort(value);
#elif defined(_MSC_VER)
        uint16_t t = (value & 0x00ff) << 8;
        t |= (value) >> 8;
        return t;
#else
        return __builtin_bswap16(value);
#endif
    }
 
    inline uint32_t byteswap(_In_ const uint32_t value)
    {
#if _MSC_VER >= 1300
        return _byteswap_ulong(value);
#elif defined(_MSC_VER)
        uint32_t t = (value & 0x000000ff) << 24;
        t |= (value & 0x0000ff00) << 8;
        t |= (value & 0x00ff0000) >> 8;
        t |= (value) >> 24;
        return t;
#else
        return __builtin_bswap32(value);
#endif
    }
 
    inline uint64_t byteswap(_In_ const uint64_t value)
    {
#if _MSC_VER >= 1300
        return _byteswap_uint64(value);
#elif defined(_MSC_VER)
        uint64_t t = (value & 0x00000000000000ff) << 56;
        t |= (value & 0x000000000000ff00) << 40;
        t |= (value & 0x0000000000ff0000) << 24;
        t |= (value & 0x00000000ff000000) << 8;
        t |= (value & 0x000000ff00000000) >> 8;
        t |= (value & 0x0000ff0000000000) >> 24;
        t |= (value & 0x00ff000000000000) >> 40;
        t |= (value) >> 56;
        return t;
#else
        return __builtin_bswap64(value);
#endif
    }
 
    inline constexpr int8_t byteswap(_In_ const char value) { return byteswap(static_cast<uint8_t>(value)); }
    inline constexpr int8_t byteswap(_In_ const int8_t value) { return byteswap(static_cast<uint8_t>(value)); }
    inline int16_t byteswap(_In_ const int16_t value) { return byteswap(static_cast<uint16_t>(value)); }
    inline int32_t byteswap(_In_ const int32_t value) { return byteswap(static_cast<uint32_t>(value)); }
    inline int64_t byteswap(_In_ const int64_t value) { return byteswap(static_cast<uint64_t>(value)); }
 
    inline float byteswap(_In_ const float value)
    {
        uint32_t r = byteswap(*reinterpret_cast<const uint32_t*>(&value));
        return *reinterpret_cast<float*>(&r);
    }
 
    inline double byteswap(_In_ const double value)
    {
        uint64_t r = byteswap(*reinterpret_cast<const uint64_t*>(&value));
        return *reinterpret_cast<double*>(&r);
    }
 
    inline void byteswap(_Inout_ uint8_t* value) { _Assume_(value); *value = byteswap(*value); }
    inline void byteswap(_Inout_ uint16_t* value) { _Assume_(value); *value = byteswap(*value); }
    inline void byteswap(_Inout_ uint32_t* value) { _Assume_(value); *value = byteswap(*value); }
    inline void byteswap(_Inout_ uint64_t* value) { _Assume_(value); *value = byteswap(*value); }
 
    inline void byteswap(_Inout_ char* value) { byteswap(reinterpret_cast<uint8_t*>(value)); }
    inline void byteswap(_Inout_ int8_t* value) { byteswap(reinterpret_cast<uint8_t*>(value)); }
    inline void byteswap(_Inout_ int16_t* value) { byteswap(reinterpret_cast<uint16_t*>(value)); }
    inline void byteswap(_Inout_ int32_t* value) { byteswap(reinterpret_cast<uint32_t*>(value)); }
    inline void byteswap(_Inout_ int64_t* value) { byteswap(reinterpret_cast<uint64_t*>(value)); }
    inline void byteswap(_Inout_ float* value) { byteswap(reinterpret_cast<uint32_t*>(value)); }
    inline void byteswap(_Inout_ double* value) { byteswap(reinterpret_cast<uint64_t*>(value)); }
}
 
#if BYTE_ORDER == BIG_ENDIAN
#define LE2HE(x) stdex::byteswap(x)
#define BE2HE(x) (x)
#define HE2LE(x) stdex::byteswap(x)
#define HE2BE(x) (x)
#else
#define LE2HE(x) (x)
#define BE2HE(x) stdex::byteswap(x)
#define HE2LE(x) (x)
#define HE2BE(x) stdex::byteswap(x)
#endif