Kontron KTAM3874-pITX - Manual (Page 99)

KTD-S0057-I Page 95 Linux® Programming Examples (DebianTM)
KTAM3874/pITX Software Guide
break; /* skip one period */
}
ptr += err * channels;
cptr -= err;
}
}
}
/* Transfer method - write and wait for room in buffer using poll */
static int wait_for_poll (snd_pcm_t *handle, struct pollfd *ufds, unsigned int count)
{
unsigned short revents;
while (1)
{
poll (ufds, count, -1);
snd_pcm_poll_descriptors_revents (handle, ufds, count, &revents);
if (revents & POLLERR)
return -EIO;
if (revents & POLLOUT)
return 0;
}
}
static int write_and_poll_loop (snd_pcm_t *handle, signed short *samples, snd_pcm_channel_area_t *areas)
{
struct pollfd *ufds;
double phase = 0;
signed short *ptr;
int err, count, cptr, init;
count = snd_pcm_poll_descriptors_count (handle);
if (count <= 0)
{
printf ("Invalid poll descriptors count\n");
return count;
}
ufds = malloc (sizeof (struct pollfd) * count);
if (ufds == NULL)
{
printf ("Not enough memory\n");
return -ENOMEM;
}
if ((err = snd_pcm_poll_descriptors (handle, ufds, count)) < 0)
{
printf ("Unable to obtain poll descriptors for playback: %s\n", snd_strerror (err));
return err;
}