ByteSwapper.h

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------
 
Copyright (c) 2006-2020, assimp team
 
 
All rights reserved.
 
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* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.
 
* 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.
 
* Neither the name of the assimp team, nor the names of its
  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the assimp team.
 
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
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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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
#ifndef AI_BYTESWAPPER_H_INC
#define AI_BYTESWAPPER_H_INC
 
#ifdef __GNUC__
#   pragma GCC system_header
#endif
 
#include <assimp/ai_assert.h>
#include <assimp/types.h>
#include <stdint.h>
 
#if _MSC_VER >= 1400
#include <stdlib.h>
#endif
 
namespace Assimp    {
// --------------------------------------------------------------------------------------
// --------------------------------------------------------------------------------------
class ByteSwap {
    ByteSwap() AI_NO_EXCEPT {}
 
public:
 
    // ----------------------------------------------------------------------
    static inline void Swap2(void* _szOut)
    {
        ai_assert(_szOut);
 
#if _MSC_VER >= 1400
        uint16_t* const szOut = reinterpret_cast<uint16_t*>(_szOut);
        *szOut = _byteswap_ushort(*szOut);
#else
        uint8_t* const szOut = reinterpret_cast<uint8_t*>(_szOut);
        std::swap(szOut[0],szOut[1]);
#endif
    }
 
    // ----------------------------------------------------------------------
    static inline void Swap4(void* _szOut)
    {
        ai_assert(_szOut);
 
#if _MSC_VER >= 1400
        uint32_t* const szOut = reinterpret_cast<uint32_t*>(_szOut);
        *szOut = _byteswap_ulong(*szOut);
#else
        uint8_t* const szOut = reinterpret_cast<uint8_t*>(_szOut);
        std::swap(szOut[0],szOut[3]);
        std::swap(szOut[1],szOut[2]);
#endif
    }
 
    // ----------------------------------------------------------------------
    static inline void Swap8(void* _szOut)
    {
    ai_assert(_szOut);
 
#if _MSC_VER >= 1400
        uint64_t* const szOut = reinterpret_cast<uint64_t*>(_szOut);
        *szOut = _byteswap_uint64(*szOut);
#else
        uint8_t* const szOut = reinterpret_cast<uint8_t*>(_szOut);
        std::swap(szOut[0],szOut[7]);
        std::swap(szOut[1],szOut[6]);
        std::swap(szOut[2],szOut[5]);
        std::swap(szOut[3],szOut[4]);
#endif
    }
 
    // ----------------------------------------------------------------------
    static inline void Swap(float* fOut) {
        Swap4(fOut);
    }
 
    // ----------------------------------------------------------------------
    static inline void Swap(double* fOut) {
        Swap8(fOut);
    }
 
 
    // ----------------------------------------------------------------------
    static inline void Swap(int16_t* fOut) {
        Swap2(fOut);
    }
 
    static inline void Swap(uint16_t* fOut) {
        Swap2(fOut);
    }
 
    // ----------------------------------------------------------------------
    static inline void Swap(int32_t* fOut){
        Swap4(fOut);
    }
 
    static inline void Swap(uint32_t* fOut){
        Swap4(fOut);
    }
 
    // ----------------------------------------------------------------------
    static inline void Swap(int64_t* fOut) {
        Swap8(fOut);
    }
 
    static inline void Swap(uint64_t* fOut) {
        Swap8(fOut);
    }
 
    // ----------------------------------------------------------------------
    template<typename Type>
    static inline Type Swapped(Type tOut)
    {
        return _swapper<Type,sizeof(Type)>()(tOut);
    }
 
private:
 
    template <typename T, size_t size> struct _swapper;
};
 
template <typename T> struct ByteSwap::_swapper<T,2> {
    T operator() (T tOut) {
        Swap2(&tOut);
        return tOut;
    }
};
 
template <typename T> struct ByteSwap::_swapper<T,4> {
    T operator() (T tOut) {
        Swap4(&tOut);
        return tOut;
    }
};
 
template <typename T> struct ByteSwap::_swapper<T,8> {
    T operator() (T tOut) {
        Swap8(&tOut);
        return tOut;
    }
};
 
 
// --------------------------------------------------------------------------------------
// ByteSwap macros for BigEndian/LittleEndian support
// --------------------------------------------------------------------------------------
#if (defined AI_BUILD_BIG_ENDIAN)
#   define AI_LE(t) (t)
#   define AI_BE(t) ByteSwap::Swapped(t)
#   define AI_LSWAP2(p)
#   define AI_LSWAP4(p)
#   define AI_LSWAP8(p)
#   define AI_LSWAP2P(p)
#   define AI_LSWAP4P(p)
#   define AI_LSWAP8P(p)
#   define LE_NCONST const
#   define AI_SWAP2(p) ByteSwap::Swap2(&(p))
#   define AI_SWAP4(p) ByteSwap::Swap4(&(p))
#   define AI_SWAP8(p) ByteSwap::Swap8(&(p))
#   define AI_SWAP2P(p) ByteSwap::Swap2((p))
#   define AI_SWAP4P(p) ByteSwap::Swap4((p))
#   define AI_SWAP8P(p) ByteSwap::Swap8((p))
#   define BE_NCONST
#else
#   define AI_BE(t) (t)
#   define AI_LE(t) ByteSwap::Swapped(t)
#   define AI_SWAP2(p)
#   define AI_SWAP4(p)
#   define AI_SWAP8(p)
#   define AI_SWAP2P(p)
#   define AI_SWAP4P(p)
#   define AI_SWAP8P(p)
#   define BE_NCONST const
#   define AI_LSWAP2(p)     ByteSwap::Swap2(&(p))
#   define AI_LSWAP4(p)     ByteSwap::Swap4(&(p))
#   define AI_LSWAP8(p)     ByteSwap::Swap8(&(p))
#   define AI_LSWAP2P(p)    ByteSwap::Swap2((p))
#   define AI_LSWAP4P(p)    ByteSwap::Swap4((p))
#   define AI_LSWAP8P(p)    ByteSwap::Swap8((p))
#   define LE_NCONST
#endif
 
 
namespace Intern {
 
// --------------------------------------------------------------------------------------------
template <typename T, bool doit>
struct ByteSwapper  {
    void operator() (T* inout) {
        ByteSwap::Swap(inout);
    }
};
 
template <typename T>
struct ByteSwapper<T,false> {
    void operator() (T*) {
    }
};
 
// --------------------------------------------------------------------------------------------
template <bool SwapEndianess, typename T, bool RuntimeSwitch>
struct Getter {
    void operator() (T* inout, bool le) {
#ifdef AI_BUILD_BIG_ENDIAN
        le =  le;
#else
        le =  !le;
#endif
        if (le) {
            ByteSwapper<T,(sizeof(T)>1?true:false)> () (inout);
        }
        else ByteSwapper<T,false> () (inout);
    }
};
 
template <bool SwapEndianess, typename T>
struct Getter<SwapEndianess,T,false> {
 
    void operator() (T* inout, bool /*le*/) {
        // static branch
        ByteSwapper<T,(SwapEndianess && sizeof(T)>1)> () (inout);
    }
};
} // end Intern
} // end Assimp
 
#endif