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#include <sys/ioctl.h>
#include <alsa/asoundlib.h>
#include <stdint.h>
#include <unistd.h>
#include "palsa.h"
#include "threading.h"
#include "streamer.h"
static inline void
le_int16 (int16_t in, char *out) {
char *pin = (char *)∈
#if !BIGENDIAN
out[0] = pin[0];
out[1] = pin[1];
#else
out[1] = pin[0];
out[0] = pin[1];
#endif
}
static snd_pcm_t *audio;
static int16_t *samplebuffer;
static int bufsize = 4096*4;
static float volume = 1;
static int alsa_terminate = 0;
static int alsa_rate = 48000;
static int state = 0; // 0 = stopped, 1 = playing, 2 = pause
static uintptr_t mutex;
static void
palsa_callback (char *stream, int len);
static void
palsa_thread (uintptr_t context);
int
palsa_init (void) {
int err;
snd_pcm_hw_params_t *hw_params;
snd_pcm_sw_params_t *sw_params;
state = 0;
if ((err = snd_pcm_open (&audio, "default", SND_PCM_STREAM_PLAYBACK, 0))) {
fprintf (stderr, "could not open audio device (%s)\n",
snd_strerror (err));
return -1;
}
if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
fprintf (stderr, "cannot allocate hardware parameter structure (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_hw_params_any (audio, hw_params)) < 0) {
fprintf (stderr, "cannot initialize hardware parameter structure (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_hw_params_set_access (audio, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
fprintf (stderr, "cannot set access type (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_hw_params_set_format (audio, hw_params, SND_PCM_FORMAT_S16_LE)) < 0) {
fprintf (stderr, "cannot set sample format (%s)\n",
snd_strerror (err));
goto open_error;
}
int val = alsa_rate;
int ret = 0;
if ((err = snd_pcm_hw_params_set_rate_near (audio, hw_params, &val, &ret)) < 0) {
fprintf (stderr, "cannot set sample rate (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_hw_params_set_channels (audio, hw_params, 2)) < 0) {
fprintf (stderr, "cannot set channel count (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_hw_params (audio, hw_params)) < 0) {
fprintf (stderr, "cannot set parameters (%s)\n",
snd_strerror (err));
goto open_error;
}
snd_pcm_hw_params_free (hw_params);
if ((err = snd_pcm_sw_params_malloc (&sw_params)) < 0) {
fprintf (stderr, "cannot allocate software parameters structure (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_sw_params_current (audio, sw_params)) < 0) {
fprintf (stderr, "cannot initialize software parameters structure (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_sw_params_set_avail_min (audio, sw_params, bufsize/4)) < 0) {
fprintf (stderr, "cannot set minimum available count (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_sw_params_set_start_threshold (audio, sw_params, 0U)) < 0) {
fprintf (stderr, "cannot set start mode (%s)\n",
snd_strerror (err));
goto open_error;
}
if ((err = snd_pcm_sw_params (audio, sw_params)) < 0) {
fprintf (stderr, "cannot set software parameters (%s)\n",
snd_strerror (err));
goto open_error;
}
/* the interface will interrupt the kernel every N frames, and ALSA
will wake up this program very soon after that.
*/
if ((err = snd_pcm_prepare (audio)) < 0) {
fprintf (stderr, "cannot prepare audio interface for use (%s)\n",
snd_strerror (err));
goto open_error;
}
// take returned fragsize
samplebuffer = malloc (bufsize);
if (!samplebuffer)
{
printf ("AUDIO: Unable to allocate memory for sample buffers.\n");
goto open_error;
}
snd_pcm_pause (audio, 1); // put into STOPPED state
alsa_terminate = 0;
mutex = mutex_create ();
thread_start (palsa_thread, 0);
return 0;
open_error:
if (audio != NULL)
{
palsa_free ();
}
return -1;
}
void
palsa_free (void) {
if (audio) {
mutex_lock (mutex);
alsa_terminate = 1;
snd_pcm_close(audio);
audio = NULL;
if (samplebuffer) {
free (samplebuffer);
samplebuffer = NULL;
}
mutex_unlock (mutex);
mutex_free (mutex);
}
}
int
palsa_play (void) {
// start updating thread
int err;
if (state == 0) {
#if 0
if ((err = snd_pcm_drop (audio)) < 0) {
fprintf (stderr, "cannot drop audio interface(%s)\n",
snd_strerror (err));
}
#endif
if ((err = snd_pcm_prepare (audio)) < 0) {
fprintf (stderr, "cannot prepare audio interface for use (%s)\n",
snd_strerror (err));
}
streamer_reset (1);
}
if (state != 1) {
state = 1;
snd_pcm_pause (audio, 0);
}
return 0;
}
int
palsa_stop (void) {
// set stop state
state = 0;
snd_pcm_pause (audio, 1);
return 0;
}
int
palsa_ispaused (void) {
// return pause state
return (state == 2);
}
int
palsa_pause (void) {
// set pause state
state = 2;
snd_pcm_pause (audio, 1);
return 0;
}
int
palsa_unpause (void) {
// unset pause state
state = 1;
snd_pcm_pause (audio, 0);
return 0;
}
void
palsa_set_volume (float vol) {
volume = vol;
}
int
palsa_get_rate (void) {
return alsa_rate;
}
static void
palsa_thread (uintptr_t context) {
int err;
for (;;) {
mutex_lock (mutex);
if (alsa_terminate) {
mutex_unlock (mutex);
break;
}
/* wait till the interface is ready for data, or 1 second
has elapsed.
*/
// if (state != 1) {
// usleep (1000);
// continue;
// }
snd_pcm_wait (audio, 1000);
#if 0
if ((err = ) < 0) {
mutex_unlock (mutex);
fprintf (stderr, "alsa poll failed (%s)\n", strerror (errno));
// continue;
}
#endif
/* find out how much space is available for playback data */
snd_pcm_sframes_t frames_to_deliver;
if ((frames_to_deliver = snd_pcm_avail_update (audio)) < 0) {
if (frames_to_deliver == -EPIPE) {
mutex_unlock (mutex);
fprintf (stderr, "an xrun occured\n");
continue;
} else {
mutex_unlock (mutex);
fprintf (stderr, "unknown ALSA avail update return value (%d)\n",
frames_to_deliver);
continue;
}
}
frames_to_deliver = frames_to_deliver > bufsize/4 ? bufsize/4 : frames_to_deliver;
/* deliver the data */
char buf[bufsize];
palsa_callback (buf, frames_to_deliver*4);
if ((err = snd_pcm_writei (audio, buf, frames_to_deliver)) < 0) {
fprintf (stderr, "write failed (%s)\n", snd_strerror (err));
}
mutex_unlock (mutex);
usleep (0); // let other threads gain some spin (avoid deadlock)
}
}
static void
palsa_callback (char *stream, int len) {
int bytesread = streamer_read (stream, len);
int ivolume = volume * 1000;
for (int i = 0; i < bytesread/2; i++) {
int16_t sample = (int16_t)(((int32_t)(((int16_t*)stream)[i])) * ivolume / 1000);
le_int16 (sample, (char*)&(((int16_t*)stream)[i]));
}
if (bytesread < len) {
memset (stream + bytesread, 0, len-bytesread);
}
}
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