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#include <alsa/asoundlib.h>
#include <alsa/seq.h>
#include <sys/time.h>
void normalize(struct timeval *tv)
{
if (tv->tv_sec == 0) {
while (tv->tv_usec <= -1000000) { tv->tv_usec += 1000000; --tv->tv_sec; }
while (tv->tv_usec >= 1000000) { tv->tv_usec -= 1000000; ++tv->tv_sec; }
} else if (tv->tv_sec < 0) {
while (tv->tv_usec <= -1000000) { tv->tv_usec += 1000000; --tv->tv_sec; }
while (tv->tv_usec > 0) { tv->tv_usec -= 1000000; ++tv->tv_sec; }
} else {
while (tv->tv_usec >= 1000000) { tv->tv_usec -= 1000000; ++tv->tv_sec; }
while (tv->tv_usec < 0) { tv->tv_usec += 1000000; --tv->tv_sec; }
}
}
int
main(int argc, char **argv)
{
snd_seq_t *handle;
int portid;
int npfd;
struct pollfd *pfd;
int queue;
int i;
int rval;
struct timeval starttv, prevdiff;
int countdown = -1;
snd_seq_queue_timer_t *timer;
snd_timer_id_t *timerid;
if (snd_seq_open(&handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
fprintf(stderr, "failed to open ALSA sequencer interface\n");
return 1;
}
snd_seq_set_client_name(handle, "generator");
if ((portid = snd_seq_create_simple_port
(handle, "generator",
SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ, 0)) < 0) {
fprintf(stderr, "failed to create ALSA sequencer port\n");
return 1;
}
if ((queue = snd_seq_alloc_queue(handle)) < 0) {
fprintf(stderr, "failed to create ALSA sequencer queue\n");
return 1;
}
/*
snd_seq_queue_timer_alloca(&timer);
snd_seq_get_queue_timer(handle, queue, timer);
snd_timer_id_alloca(&timerid);
snd_timer_id_set_class(timerid, SND_TIMER_CLASS_PCM);
snd_timer_id_set_sclass(timerid, SND_TIMER_SCLASS_NONE);
snd_timer_id_set_card(timerid, 0);
snd_timer_id_set_device(timerid, 0);
snd_timer_id_set_subdevice(timerid, 0);
snd_seq_queue_timer_set_id(timer, timerid);
snd_seq_set_queue_timer(handle, queue, timer);
*/
snd_seq_start_queue(handle, queue, 0);
snd_seq_drain_output(handle);
gettimeofday(&starttv, 0);
prevdiff.tv_sec = 0;
prevdiff.tv_usec = 0;
while (countdown != 0) {
snd_seq_queue_status_t *status;
const snd_seq_real_time_t *rtime;
struct timeval tv, diff, diffdiff;
snd_seq_queue_status_alloca(&status);
snd_seq_get_queue_status(handle, queue, status);
rtime = snd_seq_queue_status_get_real_time(status);
gettimeofday(&tv, 0);
tv.tv_sec -= starttv.tv_sec;
tv.tv_usec -= starttv.tv_usec;
normalize(&tv);
diff.tv_sec = tv.tv_sec - rtime->tv_sec;
diff.tv_usec = tv.tv_usec - rtime->tv_nsec / 1000;
normalize(&diff);
diffdiff.tv_sec = diff.tv_sec - prevdiff.tv_sec;
diffdiff.tv_usec = diff.tv_usec - prevdiff.tv_usec;
normalize(&diffdiff);
prevdiff = diff;
fprintf(stderr, " real time: %12ld sec %8ld usec\nqueue time: %12ld sec %8ld usec\n diff: %12ld sec %8ld usec\n diffdiff: %12ld sec %8ld usec\n",
tv.tv_sec, tv.tv_usec,
rtime->tv_sec, rtime->tv_nsec / 1000,
diff.tv_sec, diff.tv_usec,
diffdiff.tv_sec, diffdiff.tv_usec);
if (diffdiff.tv_usec > 5000 ||
diffdiff.tv_usec < -5000) {
fprintf(stderr, "oops! queue slipped\n");
if (tv.tv_sec < 5) {
fprintf(stderr, "(ignoring in first few seconds)\n");
} else {
countdown = 2;
}
} else {
if (countdown > 0) --countdown;
}
fprintf(stderr, "\n");
struct timespec ts;
ts.tv_sec = 1;
ts.tv_nsec = 0;
nanosleep(&ts, 0);
}
}
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