On Wed, 2001-11-28 at 15:51, Paul Davis wrote:
<cut>
>
> is there any existing code that uses poll(2) for full duplex and
> demonstrates working operation?
>
> --p
>
<cut>
I've attached the test code that I wrote with Jaroslav's modifications
which uses poll. It still has the clicking problem I mentioned.
--
Josh Green
Smurf Sound Font Editor (http://smurf.sourceforge.net)
/*
Full duplex ALSA test program
Do whatever you want with it and use it at your own risk
Josh Green <[EMAIL PROTECTED]>
Fixes by Jaroslav Kysela
November 28, 2001
*/
#include <stdio.h>
#include <alsa/asoundlib.h>
#include <string.h>
#include <sched.h>
#define OK 0
#define FAIL 1
#define TRUE 1
#define FALSE 0
char *audiobuf = NULL;
int audiobuf_bytes = 0;
int period_size = 384;
int buffer_size = 384 * 2;
snd_pcm_t *cards[2] = { NULL };
int fdcount[2] = { 0 };
struct pollfd *ufds[2] = { NULL };
int
setup_device (int index, char *device, int play)
{
int err;
snd_pcm_t *handle;
snd_pcm_hw_params_t *params; /* Hardware parameters */
snd_pcm_sw_params_t *swparams; /* Software parameters */
int thisbuf_bytes; /* this cards audio buffer size */
unsigned int rate;
snd_pcm_uframes_t start_threshold, stop_threshold;
/* Open output sound card */
if (err = snd_pcm_open (&handle, device,
play ? SND_PCM_STREAM_PLAYBACK : SND_PCM_STREAM_CAPTURE,
SND_PCM_NONBLOCK) < 0)
{
fprintf (stderr, "snd_pcm_open failed: %s\n", snd_strerror (err));
return (FAIL);
}
cards[index] = handle;
snd_pcm_hw_params_alloca (¶ms);
snd_pcm_sw_params_alloca (&swparams);
snd_pcm_hw_params_any (handle, params);
snd_pcm_hw_params_set_access(handle, params,
SND_PCM_ACCESS_RW_INTERLEAVED);
snd_pcm_hw_params_set_format (handle, params,
SND_PCM_FORMAT_S16_LE);
snd_pcm_hw_params_set_channels (handle, params, 2);
rate = snd_pcm_hw_params_set_rate_near (handle, params, 44100, 0);
if (snd_pcm_hw_params_set_period_size (handle, params, period_size, 0) < 0)
{
fprintf (stderr, "Failed to set period size!\n");
return (FAIL);
}
if (snd_pcm_hw_params_set_buffer_size (handle, params, buffer_size) < 0)
{
fprintf (stderr, "Failed to set buffer size!\n");
return (FAIL);
}
err = snd_pcm_hw_params (handle, params);
/* set software parameters */
snd_pcm_sw_params_current (handle, swparams);
snd_pcm_sw_params_set_sleep_min (handle, swparams, 0);
start_threshold = 0x7fffffff;
snd_pcm_sw_params_set_start_threshold(handle, swparams, start_threshold);
stop_threshold = buffer_size;
snd_pcm_sw_params_set_stop_threshold(handle, swparams, stop_threshold);
snd_pcm_sw_params (handle, swparams);
/* Prepare our buffer */
thisbuf_bytes = (period_size * (16 / 8) * 2) * 2;
if (audiobuf_bytes == 0)
{
audiobuf = malloc (thisbuf_bytes);
audiobuf_bytes = thisbuf_bytes;
}
else if (audiobuf_bytes != thisbuf_bytes)
{
fprintf (stderr, "audio buffers not same size (%d != %d)!\n",
audiobuf_bytes, thisbuf_bytes);
return (FAIL);
}
return (OK);
}
void
setup_pollfds (void)
{
int count1, count2;
count1 = snd_pcm_poll_descriptors_count (cards[0]);
count2 = snd_pcm_poll_descriptors_count (cards[1]);
fdcount[0] = count1;
fdcount[1] = count2;
ufds[0] = malloc (sizeof (struct pollfd) * (count1 + count2));
ufds[1] = (void *)ufds[0] + count1 * sizeof (struct pollfd);
snd_pcm_poll_descriptors (cards[0], ufds[0], count1);
snd_pcm_poll_descriptors (cards[1], ufds[1], count2);
}
void
xrun_recovery()
{
int err;
fprintf(stderr, "XRUN recovery\n");
if (err = snd_pcm_prepare(cards[0]) < 0) {
fprintf (stderr, "Failed to prepare devices\n");
exit (1);
}
if (err = snd_pcm_writei (cards[0], audiobuf, period_size * 2) < 0) {
fprintf (stderr, "Failed to write initial bytes\n");
exit (1);
}
fprintf (stderr, "Wrote %d start bytes\n", err);
snd_pcm_start(cards[1]);
}
int
main (void)
{
int i, r = 1;
short revents;
int err;
struct sched_param schp;
memset (&schp, 0, sizeof (schp));
schp.sched_priority = sched_get_priority_max (SCHED_FIFO);
if (sched_setscheduler (0, SCHED_FIFO, &schp) != 0)
fprintf (stderr, "Failed to run SCHED_FIFO\n");
/* Open output sound card */
if (setup_device (0, "plughw:0,0", TRUE) != OK)
{
fprintf (stderr, "Failed to setup output device\n");
exit (1);
}
/* Open input sound card */
if (setup_device (1, "plughw:0,0", FALSE) != OK)
{
fprintf (stderr, "Failed to setup input device\n");
exit (1);
}
setup_pollfds ();
if (snd_pcm_link (cards[1], cards[0]) < 0)
{
fprintf (stderr, "Failed to link devices\n");
exit (1);
}
if (err = snd_pcm_prepare (cards[0]) < 0) {
fprintf (stderr, "Failed to prepare devices\n");
exit (1);
}
if (err = snd_pcm_writei (cards[0], audiobuf, period_size * 2) < 0) {
fprintf (stderr, "Failed to write initial bytes\n");
exit (1);
}
fprintf (stderr, "Wrote %d start bytes\n", err);
snd_pcm_start (cards[1]);
do
{
poll (ufds[r], fdcount[r], -1);
for (i = fdcount[r]; i > 0; i--)
{
revents = ufds[r]->revents;
if (revents & POLLERR)
{
snd_pcm_t *handle;
snd_pcm_state_t state;
if (revents & POLLOUT) handle = cards[0];
else handle = cards[1];
if ((state = snd_pcm_state (handle)) == SND_PCM_STATE_XRUN)
{
fprintf (stderr, "XRUN on %s\n",
(revents & POLLOUT != 0) ? "output" : "input");
xrun_recovery();
r = 1;
break;
}
else fprintf (stderr, "Bad state %d on %s\n", state,
(revents & POLLOUT != 0) ? "output" : "input");
}
else if (revents & POLLIN)
{
err = snd_pcm_readi (cards[1], audiobuf, period_size);
if (err > 0 && err != period_size)
fprintf (stderr, "read error: requested %i read %i\n",
audiobuf_bytes, err);
r = 0;
break;
}
else if (revents & POLLOUT)
{
err = snd_pcm_writei (cards[0], audiobuf, period_size);
if (err > 0 && err != period_size)
fprintf (stderr, "write error: requested %i written %i\n",
audiobuf_bytes, err);
r = 1;
break;
}
}
}
while (1);
exit (0);
}
