Byteorder.h

/*
 * Copyright (C) 2004-2006 Marc Boris Duerner
 * Copyright (C)      2006 Aloysius Indrayanto
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * As a special exception, you may use this file as part of a free
 * software library without restriction. Specifically, if other files
 * instantiate templates or use macros or inline functions from this
 * file, or you compile this file and link it with other files to
 * produce an executable, this file does not by itself cause the
 * resulting executable to be covered by the GNU General Public
 * License. This exception does not however invalidate any other
 * reasons why the executable file might be covered by the GNU Library
 * General Public License.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifndef Pt_Byteorder_h
#define Pt_Byteorder_h

#include <Pt/Api.h>
#include <Pt/Types.h>
#include <cassert>

// build systems can specify byte-order by defining PT_LE or PT_BE.
// If these are not defined it is still possible to detect the
// endianess correctly on many common targets.
#if defined(PT_LE) || defined(PT_BE)
    // user defined endianess
#elif defined (_BYTE_ORDER)
#   if (_BYTE_ORDER == _LITTLE_ENDIAN)
#       define PT_LE
#   elif (_BYTE_ORDER == _BIG_ENDIAN)
#       define PT_BE
#   else
#       error: unknown _BYTE_ORDER
#   endif
#elif defined (__BYTE_ORDER)
#    if (__BYTE_ORDER == __LITTLE_ENDIAN)
#        define PT_LE
#    elif (__BYTE_ORDER == __BIG_ENDIAN)
#        define PT_BE
#    else
#        error: unknown __BYTE_ORDER
#    endif
#elif defined (__LITTLE_ENDIAN__) || \
      defined (i386) || defined(__i386) || defined (__i386__) || \
      defined(_X86_) || defined(sun386) || defined (_M_IX86) ||  \
      defined (_M_IA64) || defined (__ia64__) || \
      defined(__IA64__) || defined(_IA64) || \
      defined (_M_AMD64) || defined (__amd64) || \
      defined(MIPSEL) || defined(_MIPSEL) || \
      defined (ARM) || defined(__arm__) || defined(_M_ARM) || defined(_M_ARMT) || \
      defined (vax) || defined (__alpha) || defined(__THW_INTEL)
    #define PT_LE
#elif defined(__BIG_ENDIAN__) || \
      defined(__hppa__) || defined(__hppa) || defined(__hp9000) || \
      defined(__hp9000s300) || defined(hp9000s300) || \
      defined(__hp9000s700) || defined(hp9000s700) || \
      defined(__hp9000s800) || defined(hp9000s800) || defined(hp9000s820) || \
      defined(__sparc__) || defined(sparc) || defined(__sparc) || \
      defined(ibm032) || defined(ibm370) || defined(_IBMR2) || \
      defined(MIPSEB) || defined(_MIPSEB) || \
      defined(mc68000) || defined(is68k) || defined(macII) || defined(m68k) || \
      defined(apollo) || defined(__convex__) || defined(_CRAY) || defined(sel)
    #define PT_BE
#else
    #error: PT_LE or PT_BE is not defined
#endif

namespace Pt {

    template <typename T>
    inline T swab16(T value)
    {
        //union {
        //    uint16_t v;
        //    uint8_t  b[2];
        //} u;
        //u.v = value;
        //const uint8_t b0 = u.b[0];
        //const uint8_t b1 = u.b[1];
        //u.b[0] = b1;
        //u.b[1] = b0;
        //return(u.v);

        return ( (value & 0x00FF) << 8 ) |
               ( (value & 0xFF00) >> 8 );
    }

    template <typename T>
    inline T swab32(T value)
    {
        return ( (value & 0x000000FF) << 24 ) |
               ( (value & 0x0000FF00) <<  8 ) |
               ( (value & 0x00FF0000) >>  8 ) |
               ( (value & 0xFF000000) >> 24 );
    }

#ifdef PT_WITH_INT64

    template <typename T>
    inline T swab64(T value)
    {
        return ( (value & 0x00000000000000FFULL) << 56 ) |
               ( (value & 0x000000000000FF00ULL) << 40 ) |
               ( (value & 0x0000000000FF0000ULL) << 24 ) |
               ( (value & 0x00000000FF000000ULL) <<  8 ) |
               ( (value & 0x000000FF00000000ULL) >>  8 ) |
               ( (value & 0x0000FF0000000000ULL) >> 24 ) |
               ( (value & 0x00FF000000000000ULL) >> 40 ) |
               ( (value & 0xFF00000000000000ULL) >> 56 );
    }
#endif

    inline int8_t swab(int8_t value)
    { return value; }

    inline uint8_t swab(uint8_t value)
    { return value; }

    inline int16_t swab(int16_t value)
    { return swab16(value); }

    inline uint16_t swab(uint16_t value)
    { return swab16(value); }

    inline int32_t swab(int32_t value)
    { return swab32(value); }

    inline uint32_t swab(uint32_t value)
    { return swab32(value); }

#ifdef PT_WITH_INT64
    inline int64_t swab(int64_t value)
    { return swab64(value); }

    inline uint64_t swab(uint64_t value)
    { return swab64(value); }
#endif

    inline bool isBigEndian()
    {
        const int i = 1;
        return *reinterpret_cast<const int8_t*>(&i) == 0;
    }

    inline bool isLittleEndian()
    {
        const int i = 1;
        return *reinterpret_cast<const int8_t*>(&i) == 1;
    }

    template <typename T>
    inline T hostToLe(const T& value)
    {
#ifdef PT_LE
        return value;
#else
        return swab(value);
#endif
    }

    template <typename T>
    inline T leToHost(const T& value)
    {
#ifdef PT_LE
        return value;
#else
        return swab(value);
#endif
    }

    template <typename T>
    inline T hostToBe(const T& value)
    {
#ifdef PT_LE
        return swab(value);
#else
        return value;
#endif
    }

    template <typename T>
    inline T beToHost(const T& value)
    {
#ifdef PT_LE
        return swab(value);
#else
        return value;
#endif
    }

} // namespace Pt

#endif