1#include <unistd.h>
2#include <sys/time.h>
3#include <alsa/asoundlib.h>
4#include <alsa/seq.h>
5
6void normalize(struct timeval *tv)
7{
8    if (tv->tv_sec == 0) {
9	while (tv->tv_usec <= -1000000) { tv->tv_usec += 1000000; --tv->tv_sec; }
10	while (tv->tv_usec >=  1000000) { tv->tv_usec -= 1000000; ++tv->tv_sec; }
11    } else if (tv->tv_sec < 0) {
12	while (tv->tv_usec <= -1000000) { tv->tv_usec += 1000000; --tv->tv_sec; }
13	while (tv->tv_usec > 0) { tv->tv_usec -= 1000000; ++tv->tv_sec; }
14    } else {
15	while (tv->tv_usec >= 1000000) { tv->tv_usec -= 1000000; ++tv->tv_sec; }
16	while (tv->tv_usec < 0) { tv->tv_usec += 1000000; --tv->tv_sec; }
17    }
18}
19
20int
21main(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED)
22{
23    snd_seq_t *handle;
24    int portid;
25    /* int npfd;
26       struct pollfd *pfd;
27    */
28    int queue;
29    /* int i;
30       int rval;'
31    */
32    struct timeval starttv, prevdiff;
33    int countdown = -1;
34    /* snd_seq_queue_timer_t *timer;
35       snd_timer_id_t *timerid;
36    */
37
38    if (snd_seq_open(&handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
39	fprintf(stderr, "failed to open ALSA sequencer interface\n");
40	return 1;
41    }
42
43    snd_seq_set_client_name(handle, "generator");
44
45    if ((portid = snd_seq_create_simple_port
46	 (handle, "generator",
47	  SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_SUBS_READ, 0)) < 0) {
48	fprintf(stderr, "failed to create ALSA sequencer port\n");
49	return 1;
50    }
51
52    if ((queue = snd_seq_alloc_queue(handle)) < 0) {
53	fprintf(stderr, "failed to create ALSA sequencer queue\n");
54	return 1;
55    }
56/*
57    snd_seq_queue_timer_alloca(&timer);
58    snd_seq_get_queue_timer(handle, queue, timer);
59    snd_timer_id_alloca(&timerid);
60    snd_timer_id_set_class(timerid, SND_TIMER_CLASS_PCM);
61    snd_timer_id_set_sclass(timerid, SND_TIMER_SCLASS_NONE);
62    snd_timer_id_set_card(timerid, 0);
63    snd_timer_id_set_device(timerid, 0);
64    snd_timer_id_set_subdevice(timerid, 0);
65    snd_seq_queue_timer_set_id(timer, timerid);
66    snd_seq_set_queue_timer(handle, queue, timer);
67*/
68    snd_seq_start_queue(handle, queue, 0);
69    snd_seq_drain_output(handle);
70
71    gettimeofday(&starttv, 0);
72    prevdiff.tv_sec = 0;
73    prevdiff.tv_usec = 0;
74
75    while (countdown != 0) {
76
77	snd_seq_queue_status_t *status;
78	const snd_seq_real_time_t *rtime;
79	struct timeval tv, diff, diffdiff;
80	struct timespec ts;
81
82	snd_seq_queue_status_alloca(&status);
83
84	snd_seq_get_queue_status(handle, queue, status);
85	rtime = snd_seq_queue_status_get_real_time(status);
86
87	gettimeofday(&tv, 0);
88
89	tv.tv_sec -= starttv.tv_sec;
90	tv.tv_usec -= starttv.tv_usec;
91	normalize(&tv);
92
93	diff.tv_sec = tv.tv_sec - rtime->tv_sec;
94	diff.tv_usec = tv.tv_usec - rtime->tv_nsec / 1000;
95	normalize(&diff);
96
97	diffdiff.tv_sec = diff.tv_sec - prevdiff.tv_sec;
98	diffdiff.tv_usec = diff.tv_usec - prevdiff.tv_usec;
99	normalize(&diffdiff);
100	prevdiff = diff;
101
102	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",
103		tv.tv_sec, tv.tv_usec,
104		(long)rtime->tv_sec, (long)rtime->tv_nsec / 1000,
105		diff.tv_sec, diff.tv_usec,
106		(long)diffdiff.tv_sec, (long)diffdiff.tv_usec);
107
108	if (diffdiff.tv_usec >  5000 ||
109	    diffdiff.tv_usec < -5000) {
110	    fprintf(stderr, "oops! queue slipped\n");
111	    if (tv.tv_sec < 5) {
112		fprintf(stderr, "(ignoring in first few seconds)\n");
113	    } else {
114		countdown = 2;
115	    }
116	} else {
117	    if (countdown > 0) --countdown;
118	}
119
120	fprintf(stderr, "\n");
121//	sleep(1);
122	ts.tv_sec = 0;
123	ts.tv_nsec = 500000000;
124	nanosleep(&ts, 0);
125    }
126    return EXIT_SUCCESS;
127}
128
129