endianTest.h

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/*
 *  endiantTest.h - Platform endian testing
 *  Copyright (C) 2014, D Haley 

 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.

 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.

 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef _ENDIAN_TEST_H_
#define _ENDIAN_TEST_H_

#if defined (_WIN32) || defined(_WIN64) || defined(__CYGWIN__)
    #ifndef __LITTLE_ENDIAN__
        #define __LITTLE_ENDIAN__
    #endif
#else
    #ifdef __linux__
        #include <endian.h>
    #endif
#endif

#ifdef __BYTE_ORDER
    #if __BYTE_ORDER == __BIG_ENDIAN
        #ifndef __BIG_ENDIAN__
            #define __BIG_ENDIAN__
        #endif
    #elif __BYTE_ORDER == __LITTLE_ENDIAN
        #ifndef __LITTLE_ENDIAN__
            #define __LITTLE_ENDIAN__
        #endif
    #elif __BYTE_ORDER == __PDP_ENDIAN
        #ifndef __ARM_ENDIAN__
            #define __ARM_ENDIAN__
        #endif
    #else
        #error "Endian determination failed"
    #endif
#endif

const int ENDIAN_TEST=1;
//Run-time detection
inline int is_bigendian() { return (*(char*)&ENDIAN_TEST) == 0 ;}

inline int is_littleendian() { return (*(char*)&ENDIAN_TEST) == 1 ;}

#include <inttypes.h>

inline void floatSwapBytes(float *inFloat)
{
    //Use a union to avoid strict-aliasing error
    union FloatSwapUnion{
       float f;
       char c[4];
    } ;
    FloatSwapUnion fa,fb;
    fa.f = *inFloat;

    fb.c[0] = fa.c[3];
    fb.c[1] = fa.c[2];
    fb.c[2] = fa.c[1];
    fb.c[3] = fa.c[0];

    *inFloat=fb.f;
}

inline void int4SwapBytes(int32_t *inInt)
{
    //Use a union to avoid strict-aliasing error
    union IntSwapUnion{
       int i;
       char c[4];
    } ;
    IntSwapUnion ia,ib;
    ia.i = *inInt;

    ib.c[0] = ia.c[3];
    ib.c[1] = ia.c[2];
    ib.c[2] = ia.c[1];
    ib.c[3] = ia.c[0];

    *inInt=ib.i;
}

#endif