Директива препроцессора pragma

 
#if defined(WIN32) || defined(__WATCOMC__) || defined(_WIN32) || defined(__WIN32__)
    #define __PACKED                         /* dummy */
#else
    #define __PACKED __attribute__((packed)) /* gcc packed */
#endif
 
 
/*
[
    [DESCRIPTION]
    Writes out the contents of a record buffer to a file.
 
    [PARAMETERS]
 
    [RETURN_VALUE]
    void
 
    [REMARKS]
]
*/
void WriteWavHeader(FILE *fp, FMOD::Sound *sound, int length)
{
    int             channels, bits;
    float           rate;
 
    if (!sound)
    {
        return;
    }
 
    fseek(fp, 0, SEEK_SET);
 
    sound->getFormat  (0, 0, &channels, &bits);
    sound->getDefaults(&rate, 0, 0, 0);
 
    {
        #if defined(WIN32) || defined(_WIN64) || defined(__WATCOMC__) || defined(_WIN32) || defined(__WIN32__)
        #pragma pack(1)
        #endif
        
        /*
            WAV Structures
        */
        typedef struct
        {
            signed char id[4];
            int         size;
        } RiffChunk;
    
        struct
        {
            RiffChunk       chunk           __PACKED;
            unsigned short  wFormatTag      __PACKED;    /* format type  */
            unsigned short  nChannels       __PACKED;    /* number of channels (i.e. mono, stereo...)  */
            unsigned int    nSamplesPerSec  __PACKED;    /* sample rate  */
            unsigned int    nAvgBytesPerSec __PACKED;    /* for buffer estimation  */
            unsigned short  nBlockAlign     __PACKED;    /* block size of data  */
            unsigned short  wBitsPerSample  __PACKED;    /* number of bits per sample of mono data */
        } FmtChunk  = { {{'f','m','t',' '}, sizeof(FmtChunk) - sizeof(RiffChunk) }, 1, channels, (int)rate, (int)rate * channels * bits / 8, 1 * channels * bits / 8, bits } __PACKED;
 
        struct
        {
            RiffChunk   chunk;
        } DataChunk = { {{'d','a','t','a'}, length } };
 
        struct
        {
            RiffChunk   chunk;
            signed char rifftype[4];
        } WavHeader = { {{'R','I','F','F'}, sizeof(FmtChunk) + sizeof(RiffChunk) + length }, {'W','A','V','E'} };
 
        #if defined(WIN32) || defined(_WIN64) || defined(__WATCOMC__) || defined(_WIN32) || defined(__WIN32__)
        #pragma pack()
        #endif
      
        /*
            Write out the WAV header.
        */
        fwrite(&WavHeader, sizeof(WavHeader), 1, fp);
        fwrite(&FmtChunk, sizeof(FmtChunk), 1, fp);
        fwrite(&DataChunk, sizeof(DataChunk), 1, fp);
    }
}

#define __PACKED

#define __PACKED __attribute__((packed)) /* gcc packed */