/usr/share/doc/libasound2-dev/examples/queue_timer.c is in libasound2-dev 1.1.0-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 | #include <unistd.h>
#include <sys/time.h>
#include <alsa/asoundlib.h>
#include <alsa/seq.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 ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED)
{
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;
struct timespec ts;
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,
(long)rtime->tv_sec, (long)rtime->tv_nsec / 1000,
diff.tv_sec, diff.tv_usec,
(long)diffdiff.tv_sec, (long)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");
// sleep(1);
ts.tv_sec = 0;
ts.tv_nsec = 500000000;
nanosleep(&ts, 0);
}
return EXIT_SUCCESS;
}
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