byte_order_helper.h

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#ifndef _PFC_BYTE_ORDER_HELPER_
#define _PFC_BYTE_ORDER_HELPER_

namespace pfc {
    void byteswap_raw(void * p_buffer,t_size p_bytes);

    template<typename T> T byteswap_t(T p_source);

    template<> inline char byteswap_t<char>(char p_source) {return p_source;}
    template<> inline unsigned char byteswap_t<unsigned char>(unsigned char p_source) {return p_source;}
    template<> inline signed char byteswap_t<signed char>(signed char p_source) {return p_source;}

    template<typename T> T byteswap_int_t(T p_source) {
        enum { width = sizeof(T) };
        typedef typename sized_int_t<width>::t_unsigned tU;
        tU in = p_source, out = 0;
        for(unsigned walk = 0; walk < width; ++walk) {
            out |= ((in >> (walk * 8)) & 0xFF) << ((width - 1 - walk) * 8);
        }
        return out;
    }

#ifdef _MSC_VER//does this even help with performance/size?
    template<> inline wchar_t byteswap_t<wchar_t>(wchar_t p_source) {return _byteswap_ushort(p_source);}

    template<> inline short byteswap_t<short>(short p_source) {return _byteswap_ushort(p_source);}
    template<> inline unsigned short byteswap_t<unsigned short>(unsigned short p_source) {return _byteswap_ushort(p_source);}

    template<> inline int byteswap_t<int>(int p_source) {return _byteswap_ulong(p_source);}
    template<> inline unsigned int byteswap_t<unsigned int>(unsigned int p_source) {return _byteswap_ulong(p_source);}

    template<> inline long byteswap_t<long>(long p_source) {return _byteswap_ulong(p_source);}
    template<> inline unsigned long byteswap_t<unsigned long>(unsigned long p_source) {return _byteswap_ulong(p_source);}

    template<> inline long long byteswap_t<long long>(long long p_source) {return _byteswap_uint64(p_source);}
    template<> inline unsigned long long byteswap_t<unsigned long long>(unsigned long long p_source) {return _byteswap_uint64(p_source);}
#else
    template<> inline wchar_t byteswap_t<wchar_t>(wchar_t p_source) {return byteswap_int_t(p_source);}

    template<> inline short byteswap_t<short>(short p_source) {return byteswap_int_t(p_source);}
    template<> inline unsigned short byteswap_t<unsigned short>(unsigned short p_source) {return byteswap_int_t(p_source);}

    template<> inline int byteswap_t<int>(int p_source) {return byteswap_int_t(p_source);}
    template<> inline unsigned int byteswap_t<unsigned int>(unsigned int p_source) {return byteswap_int_t(p_source);}

    template<> inline long byteswap_t<long>(long p_source) {return byteswap_int_t(p_source);}
    template<> inline unsigned long byteswap_t<unsigned long>(unsigned long p_source) {return byteswap_int_t(p_source);}

    template<> inline long long byteswap_t<long long>(long long p_source) {return byteswap_int_t(p_source);}
    template<> inline unsigned long long byteswap_t<unsigned long long>(unsigned long long p_source) {return byteswap_int_t(p_source);}
#endif

    template<> inline float byteswap_t<float>(float p_source) {
        float ret;
        *(t_uint32*) &ret = byteswap_t(*(const t_uint32*)&p_source );
        return ret;
    }

    template<> inline double byteswap_t<double>(double p_source) {
        double ret;
        *(t_uint64*) &ret = byteswap_t(*(const t_uint64*)&p_source );
        return ret;
    }

    //blargh at GUID byteswap issue
    template<> inline GUID byteswap_t<GUID>(GUID p_guid) {
        GUID ret;
        ret.Data1 = pfc::byteswap_t(p_guid.Data1);
        ret.Data2 = pfc::byteswap_t(p_guid.Data2);
        ret.Data3 = pfc::byteswap_t(p_guid.Data3);
        ret.Data4[0] = p_guid.Data4[0];
        ret.Data4[1] = p_guid.Data4[1];
        ret.Data4[2] = p_guid.Data4[2];
        ret.Data4[3] = p_guid.Data4[3];
        ret.Data4[4] = p_guid.Data4[4];
        ret.Data4[5] = p_guid.Data4[5];
        ret.Data4[6] = p_guid.Data4[6];
        ret.Data4[7] = p_guid.Data4[7];
        return ret;
    }


    
};

#ifdef _MSC_VER

#if defined(_M_IX86) || defined(_M_X64) || defined(_M_ARM)
#define PFC_BYTE_ORDER_IS_BIG_ENDIAN 0
#endif

#else//_MSC_VER

#if defined(__APPLE__)
#include <architecture/byte_order.h>
#else
#include <endian.h>
#endif

#if __BYTE_ORDER == __LITTLE_ENDIAN
#define PFC_BYTE_ORDER_IS_BIG_ENDIAN 0
#else
#define PFC_BYTE_ORDER_IS_BIG_ENDIAN 1
#endif

#endif//_MSC_VER

#ifdef PFC_BYTE_ORDER_IS_BIG_ENDIAN
#define PFC_BYTE_ORDER_IS_LITTLE_ENDIAN (!(PFC_BYTE_ORDER_IS_BIG_ENDIAN))
#else
#error please update byte order #defines
#endif


namespace pfc {
    static const bool byte_order_is_big_endian = !!PFC_BYTE_ORDER_IS_BIG_ENDIAN;
    static const bool byte_order_is_little_endian = !!PFC_BYTE_ORDER_IS_LITTLE_ENDIAN;

    template<typename T> T byteswap_if_be_t(T p_param) {return byte_order_is_big_endian ? byteswap_t(p_param) : p_param;}
    template<typename T> T byteswap_if_le_t(T p_param) {return byte_order_is_little_endian ? byteswap_t(p_param) : p_param;}
}

namespace byte_order {

#if PFC_BYTE_ORDER_IS_BIG_ENDIAN//big endian
    template<typename T> inline void order_native_to_le_t(T& param) {param = pfc::byteswap_t(param);}
    template<typename T> inline void order_native_to_be_t(T& param) {}
    template<typename T> inline void order_le_to_native_t(T& param) {param = pfc::byteswap_t(param);}
    template<typename T> inline void order_be_to_native_t(T& param) {}
#else//little endian
    template<typename T> inline void order_native_to_le_t(T& param) {}
    template<typename T> inline void order_native_to_be_t(T& param) {param = pfc::byteswap_t(param);}
    template<typename T> inline void order_le_to_native_t(T& param) {}
    template<typename T> inline void order_be_to_native_t(T& param) {param = pfc::byteswap_t(param);}
#endif
};



namespace pfc {
    template<typename TInt,unsigned width,bool IsBigEndian>
    class __EncodeIntHelper {
    public:
        inline static void Run(TInt p_value,t_uint8 * p_out) {
            *p_out = (t_uint8)(p_value);
            __EncodeIntHelper<TInt,width-1,IsBigEndian>::Run(p_value >> 8,p_out + (IsBigEndian ? -1 : 1));
        }
    };

    template<typename TInt,bool IsBigEndian>
    class __EncodeIntHelper<TInt,1,IsBigEndian> {
    public:
        inline static void Run(TInt p_value,t_uint8* p_out) {
            *p_out = (t_uint8)(p_value);
        }
    };
    template<typename TInt,bool IsBigEndian>
    class __EncodeIntHelper<TInt,0,IsBigEndian> {
    public:
        inline static void Run(TInt,t_uint8*) {}
    };

    template<typename TInt>
    inline void encode_little_endian(t_uint8 * p_buffer,TInt p_value) {
        __EncodeIntHelper<TInt,sizeof(TInt),false>::Run(p_value,p_buffer);
    }
    template<typename TInt>
    inline void encode_big_endian(t_uint8 * p_buffer,TInt p_value) {
        __EncodeIntHelper<TInt,sizeof(TInt),true>::Run(p_value,p_buffer + (sizeof(TInt) - 1));
    }


    template<typename TInt,unsigned width,bool IsBigEndian>
    class __DecodeIntHelper {
    public:
        inline static TInt Run(const t_uint8 * p_in) {
            return (__DecodeIntHelper<TInt,width-1,IsBigEndian>::Run(p_in + (IsBigEndian ? -1 : 1)) << 8) + *p_in;
        }
    };
    
    template<typename TInt,bool IsBigEndian>
    class __DecodeIntHelper<TInt,1,IsBigEndian> {
    public:
        inline static TInt Run(const t_uint8* p_in) {return *p_in;}
    };

    template<typename TInt,bool IsBigEndian>
    class __DecodeIntHelper<TInt,0,IsBigEndian> {
    public:
        inline static TInt Run(const t_uint8*) {return 0;}
    };

    template<typename TInt>
    inline void decode_little_endian(TInt & p_out,const t_uint8 * p_buffer) {
        p_out = __DecodeIntHelper<TInt,sizeof(TInt),false>::Run(p_buffer);
    }

    template<typename TInt>
    inline void decode_big_endian(TInt & p_out,const t_uint8 * p_buffer) {
        p_out = __DecodeIntHelper<TInt,sizeof(TInt),true>::Run(p_buffer + (sizeof(TInt) - 1));
    }

    template<typename TInt>
    inline TInt decode_little_endian(const t_uint8 * p_buffer) {
        TInt temp;
        decode_little_endian(temp,p_buffer);
        return temp;
    }

    template<typename TInt>
    inline TInt decode_big_endian(const t_uint8 * p_buffer) {
        TInt temp;
        decode_big_endian(temp,p_buffer);
        return temp;
    }

    template<bool IsBigEndian,typename TInt>
    inline void decode_endian(TInt & p_out,const t_uint8 * p_buffer) {
        if (IsBigEndian) decode_big_endian(p_out,p_buffer);
        else decode_little_endian(p_out,p_buffer);
    }
    template<bool IsBigEndian,typename TInt>
    inline void encode_endian(t_uint8 * p_buffer,TInt p_in) {
        if (IsBigEndian) encode_big_endian(p_in,p_buffer);
        else encode_little_endian(p_in,p_buffer);
    }



    template<unsigned width>
    inline void reverse_bytes(t_uint8 * p_buffer) {
        pfc::swap_t(p_buffer[0],p_buffer[width-1]);
        reverse_bytes<width-2>(p_buffer+1);
    }

    template<> inline void reverse_bytes<1>(t_uint8 * p_buffer) { }
    template<> inline void reverse_bytes<0>(t_uint8 * p_buffer) { }

}



#endif