/*

Example 3 - Simple sound playback

This example reads standard from input and writes
to the default PCM device 

*/

/* Use the newer ALSA API */
#define ALSA_PCM_NEW_HW_PARAMS_API

#include <alsa/asoundlib.h>


  snd_pcm_t *handle;
  snd_pcm_hw_params_t *params;
  snd_pcm_uframes_t frames;
  char *buffer;

void init() {
int rc;
int dir;
int val;

/* Open PCM device for playback. */
rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0);
if (rc < 0) {
    fprintf(stderr, "unable to open pcm device: %s\n",
            snd_strerror(rc));
    exit(1);
 }

/* Allocate a hardware parameters object. */
snd_pcm_hw_params_alloca(&params);

/* Fill it in with default values. */
snd_pcm_hw_params_any(handle, params);

/* Set the desired hardware parameters. */

/* Interleaved mode */
snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);

/* Signed 16-bit big-endian format */
snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_BE);

/* Two channels (stereo) */
snd_pcm_hw_params_set_channels(handle, params, 2);

/* 44100 bits/second sampling rate (CD quality) */
val = 44100;
snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir);

/* Set period size to 32 frames. */
frames = 32;
snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir);

/* Write the parameters to the driver */
rc = snd_pcm_hw_params(handle, params);
if (rc < 0) {
    fprintf(stderr, "unable to set hw parameters: %s\n", snd_strerror(rc));
    exit(1);
  }
}

void suona(int fd) {
int rc;
int size;
int dir;

 /* Use a buffer large enough to hold one period */
  snd_pcm_hw_params_get_period_size(params, &frames, &dir);
  size = frames * 4; /* 2 bytes/sample, 2 channels */
  buffer = (char *) malloc(size);
 rc=1;
  while (rc!=0) {
    rc = read(fd, buffer, size);
    if (rc == 0) {
      fprintf(stderr, "end of file on input\n");
      break;
    } else if (rc != size) {
      fprintf(stderr, "short read: read %d bytes\n", rc);
    }
    rc = snd_pcm_writei(handle, buffer, frames);
    if (rc == -EPIPE) {
      /* EPIPE means underrun */
      fprintf(stderr, "underrun occurred\n");
      snd_pcm_prepare(handle);
    } else if (rc < 0) {
      fprintf(stderr, "error from writei: %s\n", snd_strerror(rc));
    }  else if (rc != (int)frames) {
      fprintf(stderr, "short write, write %d frames\n", rc);
    }
  }
 
}

int main() {

int fd;

init() ; 
fd=open("audio_02.cdr",O_RDONLY);
suona(fd);
close(fd);

fd=open("audio_03.cdr",O_RDONLY);
suona(fd);
close(fd);
snd_pcm_drain(handle);
snd_pcm_close(handle);
free(buffer);
  
return 0;
}