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Implemented snd_pcm_sw_params_(set|get)_period_event for interrupt wakeup like behaviour

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Actually, PCM timer is used as source for poll(). It might be optimized
in the kernel code later.
This commit is contained in:
Jaroslav Kysela 2008-05-09 16:02:02 +02:00
parent c88672d86f
commit 8aaccc9484
6 changed files with 231 additions and 7 deletions
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24
test/pcm.c
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@ -19,8 +19,9 @@ static unsigned int channels = 1; /* count of channels */
static unsigned int buffer_time = 500000; /* ring buffer length in us */
static unsigned int period_time = 100000; /* period time in us */
static double freq = 440; /* sinusoidal wave frequency in Hz */
static int verbose = 0; /* verbose flag */
static int verbose = 0; /* verbose flag */
static int resample = 1; /* enable alsa-lib resampling */
static int period_event = 0; /* produce poll event after each period */
static snd_pcm_sframes_t buffer_size;
static snd_pcm_sframes_t period_size;
@ -172,11 +173,20 @@ static int set_swparams(snd_pcm_t *handle, snd_pcm_sw_params_t *swparams)
return err;
}
/* allow the transfer when at least period_size samples can be processed */
err = snd_pcm_sw_params_set_avail_min(handle, swparams, period_size);
/* or disable this mechanism when period event is enabled (aka interrupt like style processing) */
err = snd_pcm_sw_params_set_avail_min(handle, swparams, period_event ? buffer_size : period_size);
if (err < 0) {
printf("Unable to set avail min for playback: %s\n", snd_strerror(err));
return err;
}
/* enable period events when requested */
if (period_event) {
err = snd_pcm_sw_params_set_period_event(handle, swparams, 1);
if (err < 0) {
printf("Unable to set period event: %s\n", snd_strerror(err));
return err;
}
}
/* write the parameters to the playback device */
err = snd_pcm_sw_params(handle, swparams);
if (err < 0) {
@ -192,6 +202,8 @@ static int set_swparams(snd_pcm_t *handle, snd_pcm_sw_params_t *swparams)
static int xrun_recovery(snd_pcm_t *handle, int err)
{
if (verbose)
printf("stream recovery\n");
if (err == -EPIPE) { /* under-run */
err = snd_pcm_prepare(handle);
if (err < 0)
@ -711,6 +723,8 @@ static void help(void)
"-m,--method transfer method\n"
"-o,--format sample format\n"
"-v,--verbose show the PCM setup parameters\n"
"-n,--noresample do not resample\n"
"-e,--pevent enable poll event after each period\n"
"\n");
printf("Recognized sample formats are:");
for (k = 0; k < SND_PCM_FORMAT_LAST; ++k) {
@ -740,6 +754,7 @@ int main(int argc, char *argv[])
{"format", 1, NULL, 'o'},
{"verbose", 1, NULL, 'v'},
{"noresample", 1, NULL, 'n'},
{"pevent", 1, NULL, 'e'},
{NULL, 0, NULL, 0},
};
snd_pcm_t *handle;
@ -757,7 +772,7 @@ int main(int argc, char *argv[])
morehelp = 0;
while (1) {
int c;
if ((c = getopt_long(argc, argv, "hD:r:c:f:b:p:m:o:vn", long_option, NULL)) < 0)
if ((c = getopt_long(argc, argv, "hD:r:c:f:b:p:m:o:vne", long_option, NULL)) < 0)
break;
switch (c) {
case 'h':
@ -814,6 +829,9 @@ int main(int argc, char *argv[])
case 'n':
resample = 0;
break;
case 'e':
period_event = 1;
break;
}
}