alsa.c

#include <alsa/asoundlib.h>
#include <alsa/pcm.h>
#include <math.h>
#define BUFFER_LEN 480000

static char *device = "default";                       //soundcard
snd_output_t *output = NULL;
float buffer [BUFFER_LEN];


int main(void)
{
  int err;
  int j,k;

  //int f = 440;                //frequency

  int f = 880;                //frequency
  int fs = 48000;             //sampling frequency

  snd_pcm_t *handle;
  snd_pcm_sframes_t frames;

  // ERROR HANDLING
  if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
    printf("Playback open error: %s\n", snd_strerror(err));
    exit(EXIT_FAILURE);
  }

  if ((err = snd_pcm_set_params(handle,
                                SND_PCM_FORMAT_FLOAT,
                                SND_PCM_ACCESS_RW_INTERLEAVED,
                                1,
                                48000,
                                1,
                                500000)) < 0) {   
    printf("Playback open error: %s\n", snd_strerror(err));
    exit(EXIT_FAILURE);
  }

  // SINE WAVE
  int freq = 0;
  for ( freq = 1000; freq < 20000; freq *= 2 ) {
    printf("Sine tone at %dHz\n ",freq);

    for (k=0; k<BUFFER_LEN; k++){
        buffer[k] = ( sin(2*M_PI * k * freq));                 //sine wave value generation                        
    }       
    
    for (j=0; j<5; j++){
      frames = snd_pcm_writei(handle, buffer, BUFFER_LEN);    //sending values to sound driver
    }
  }

  snd_pcm_close(handle);
  return 0;
}