endianness.h

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/*
* Copyright 2016 Autodesk, Inc. All rights reserved.
* Use of this software is subject to the terms of the Autodesk license agreement and any attachments or Appendices thereto provided at the time of installation or download,
* or which otherwise accompanies this software in either electronic or hard copy form, or which is signed by you and accepted by Autodesk.
*/

#pragma once

#include "gwnavruntime/base/types.h"

namespace Kaim
{

class Endianness
{
public:
    enum Type
    {
        LittleEndian = 0, 
        BigEndian = 1,    
    };

    enum Target
    {
        SYSTEM_ENDIANNESS = 0,         
        INVERSE_SYSTEM_ENDIANNESS = 1, 
    };

    static Type GetSystemEndianness() { return LittleEndian; }

    static Type GetInverseSystemEndianness() { return GetInverseEndianness(GetSystemEndianness()); }

    static Type GetInverseEndianness(Type endianness) { return (endianness == BigEndian) ? LittleEndian : BigEndian; }

    static Type GetEndiannessFromMem32(const KyUInt32* mem) { return (*mem == 0) ? LittleEndian : BigEndian; }

    static void SetEndiannessToMem32(Type endianness, KyUInt32* mem)
    {
        *mem = 0;
        if (endianness == BigEndian)
            *((char*)mem) = 1; // set first byte to 1 regardless of the endianness
    }

    static void SwapEndiannessInMem32(KyUInt32* mem)
    {
        Type endianness = GetEndiannessFromMem32(mem);
        Type inverseEndianness = GetInverseEndianness(endianness);
        SetEndiannessToMem32(inverseEndianness, mem);
    }

    static inline void Swap16(void* x)
    {
        (*(KyUInt16*)x) =
            ( (*(KyUInt16*)x) >> 8 ) |
            ( (*(KyUInt16*)x) << 8 );
    }

    static inline void Swap32(void* x)
    {
        (*(KyUInt32*)x) =
            ( ( (*(KyUInt32*)x) >> 24 )              ) |
            ( ( (*(KyUInt32*)x) <<  8 ) & 0x00FF0000 ) |
            ( ( (*(KyUInt32*)x) >>  8 ) & 0x0000FF00 ) |
            ( ( (*(KyUInt32*)x) << 24 )              );
    }

    static inline void Swap64(void* x)
    {
        (*(KyUInt64*)x) =
            ( ( (*(KyUInt64*)x) << 56 )                         ) |
            ( ( (*(KyUInt64*)x) << 40 ) & 0x00FF000000000000ULL ) |
            ( ( (*(KyUInt64*)x) << 24 ) & 0x0000FF0000000000ULL ) |
            ( ( (*(KyUInt64*)x) <<  8 ) & 0x000000FF00000000ULL ) |
            ( ( (*(KyUInt64*)x) >>  8 ) & 0x00000000FF000000ULL ) |
            ( ( (*(KyUInt64*)x) >> 24 ) & 0x0000000000FF0000ULL ) |
            ( ( (*(KyUInt64*)x) >> 40 ) & 0x000000000000FF00ULL ) |
            ( ( (*(KyUInt64*)x) >> 56 )                         );
    }
};

inline void SwapEndianness(Endianness::Target, KyInt32&  x ) { Endianness::Swap32(&x); }
inline void SwapEndianness(Endianness::Target, KyUInt32& x ) { Endianness::Swap32(&x); }
inline void SwapEndianness(Endianness::Target, KyInt16&  x ) { Endianness::Swap16(&x); }
inline void SwapEndianness(Endianness::Target, KyUInt16& x ) { Endianness::Swap16(&x); }
inline void SwapEndianness(Endianness::Target, KyInt8&     ) {}
inline void SwapEndianness(Endianness::Target, KyUInt8&    ) {}
inline void SwapEndianness(Endianness::Target, char&       ) {}
inline void SwapEndianness(Endianness::Target, KyFloat32& x) { Endianness::Swap32(&x); }
inline void SwapEndianness(Endianness::Target, KyInt64&  x ) { Endianness::Swap64(&x); }
inline void SwapEndianness(Endianness::Target, KyUInt64& x ) { Endianness::Swap64(&x); }


template <class OSTREAM>
inline OSTREAM& operator<<(OSTREAM& os, Endianness::Type& endianess)
{
    switch (endianess)
    {
    case Endianness::LittleEndian: os << "LittleEndian"; break;
    case Endianness::BigEndian:    os << "BigEndian";    break;
    }
    return os;
}


}