gistfile1.c

void fill_audio(void *udata, Uint8 *stream, int len)
{
    int fLen = len/sizeof(float);

    /* Mix as much data as possible */
    // copy the output to the stream
    for(int i=0;i<fLen;i+=2){
        // =======================
        //
        //  my c code goes here
        // =======================
        ((float*)stream)[i] = 0;
        ((float*)stream)[i+1] = 0;
    }
}
int main(int argc, char **argv){
    SDL_AudioSpec wanted;
    /* Set the audio format */
    wanted.freq = 44100;
    wanted.format = AUDIO_F32;
    wanted.channels = 2;    /* 1 = mono, 2 = stereo */
    wanted.samples = 2048;  /* Good low-latency value for callback */
    wanted.callback = &fill_audio;
    wanted.userdata = NULL;
    
    output = new float[2048*2];    

    /* Open the audio device, forcing the desired format */
    if ( SDL_OpenAudio(&wanted, NULL) < 0 ) {
        fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError());
        return(-1);
    }
    SDL_PauseAudio(0);
}