1#ifndef _GNU_SOURCE
2#define _GNU_SOURCE
3#endif
4
5#include <assert.h>
6#include <inttypes.h>
7#include <time.h>
8#include <unistd.h>
9#include <pthread.h>
10
11#include <alsa/asoundlib.h>
12
13#define SAMPLE_RATE 44100
14#define CHANNELS 2
15
16static uint64_t timespec_us(const struct timespec *ts) {
17    return
18        ts->tv_sec * 1000000LLU +
19        ts->tv_nsec / 1000LLU;
20}
21
22int main(int argc, char *argv[]) {
23    const char *dev;
24    int r, cap, count = 0;
25    snd_pcm_hw_params_t *hwparams;
26    snd_pcm_sw_params_t *swparams;
27    snd_pcm_status_t *status;
28    snd_pcm_t *pcm;
29    unsigned rate = SAMPLE_RATE;
30    unsigned periods = 2;
31    snd_pcm_uframes_t boundary, buffer_size = SAMPLE_RATE/10; /* 100s */
32    int dir = 1;
33    int fillrate;
34    struct timespec start, last_timestamp = { 0, 0 };
35    uint64_t start_us, last_us = 0;
36    snd_pcm_sframes_t last_avail = 0, last_delay = 0;
37    struct pollfd *pollfds;
38    int n_pollfd;
39    int64_t sample_count = 0;
40    uint16_t *samples;
41    struct sched_param sp;
42
43    r = -1;
44#ifdef _POSIX_PRIORITY_SCHEDULING
45    sp.sched_priority = 5;
46    r = pthread_setschedparam(pthread_self(), SCHED_RR, &sp);
47#endif
48    if (r)
49        printf("Could not get RT prio. :(\n");
50
51    snd_pcm_hw_params_alloca(&hwparams);
52    snd_pcm_sw_params_alloca(&swparams);
53    snd_pcm_status_alloca(&status);
54
55    r = clock_gettime(CLOCK_MONOTONIC, &start);
56    assert(r == 0);
57
58    start_us = timespec_us(&start);
59
60    dev = argc > 1 ? argv[1] : "front:0";
61    cap = argc > 2 ? atoi(argv[2]) : 0;
62    fillrate = argc > 3 ? atoi(argv[3]) : 1;
63    assert(fillrate > 0);
64
65    samples = calloc(fillrate, CHANNELS*sizeof(uint16_t));
66    assert(samples);
67
68    if (cap == 0)
69      r = snd_pcm_open(&pcm, dev, SND_PCM_STREAM_PLAYBACK, 0);
70    else
71      r = snd_pcm_open(&pcm, dev, SND_PCM_STREAM_CAPTURE, 0);
72    assert(r == 0);
73
74    r = snd_pcm_hw_params_any(pcm, hwparams);
75    assert(r == 0);
76
77    r = snd_pcm_hw_params_set_rate_resample(pcm, hwparams, 0);
78    assert(r == 0);
79
80    r = snd_pcm_hw_params_set_access(pcm, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED);
81    assert(r == 0);
82
83    r = snd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16_LE);
84    assert(r == 0);
85
86    r = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, NULL);
87    assert(r == 0);
88
89    r = snd_pcm_hw_params_set_channels(pcm, hwparams, CHANNELS);
90    assert(r == 0);
91
92    r = snd_pcm_hw_params_set_periods_integer(pcm, hwparams);
93    assert(r == 0);
94
95    r = snd_pcm_hw_params_set_periods_near(pcm, hwparams, &periods, &dir);
96    assert(r == 0);
97
98    r = snd_pcm_hw_params_set_buffer_size_near(pcm, hwparams, &buffer_size);
99    assert(r == 0);
100
101    r = snd_pcm_hw_params(pcm, hwparams);
102    assert(r == 0);
103
104    r = snd_pcm_hw_params_current(pcm, hwparams);
105    assert(r == 0);
106
107    r = snd_pcm_sw_params_current(pcm, swparams);
108    assert(r == 0);
109
110    if (cap == 0)
111      r = snd_pcm_sw_params_set_avail_min(pcm, swparams, 1);
112    else
113      r = snd_pcm_sw_params_set_avail_min(pcm, swparams, 0);
114    assert(r == 0);
115
116    r = snd_pcm_sw_params_set_period_event(pcm, swparams, 0);
117    assert(r == 0);
118
119    r = snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size);
120    assert(r == 0);
121    r = snd_pcm_sw_params_set_start_threshold(pcm, swparams, buffer_size - (buffer_size % fillrate));
122    assert(r == 0);
123
124    r = snd_pcm_sw_params_get_boundary(swparams, &boundary);
125    assert(r == 0);
126    r = snd_pcm_sw_params_set_stop_threshold(pcm, swparams, boundary);
127    assert(r == 0);
128
129    r = snd_pcm_sw_params_set_tstamp_mode(pcm, swparams, SND_PCM_TSTAMP_ENABLE);
130    assert(r == 0);
131
132    r = snd_pcm_sw_params(pcm, swparams);
133    assert(r == 0);
134
135    r = snd_pcm_sw_params_current(pcm, swparams);
136    assert(r == 0);
137
138/*     assert(snd_pcm_hw_params_is_monotonic(hwparams) > 0); */
139
140    n_pollfd = snd_pcm_poll_descriptors_count(pcm);
141    assert(n_pollfd > 0);
142
143    pollfds = malloc(sizeof(struct pollfd) * n_pollfd);
144    assert(pollfds);
145
146    r = snd_pcm_poll_descriptors(pcm, pollfds, n_pollfd);
147    assert(r == n_pollfd);
148
149    printf("Starting. Buffer size is %u frames\n", (unsigned int) buffer_size);
150
151    if (cap) {
152      r = snd_pcm_start(pcm);
153      assert(r == 0);
154    }
155
156    for (;;) {
157        snd_pcm_sframes_t avail, delay;
158        struct timespec now, timestamp;
159        unsigned short revents;
160        int handled = 0;
161        uint64_t now_us, timestamp_us;
162        snd_pcm_state_t state;
163        unsigned long long pos;
164
165        r = poll(pollfds, n_pollfd, 0);
166        assert(r >= 0);
167
168        r = snd_pcm_poll_descriptors_revents(pcm, pollfds, n_pollfd, &revents);
169        assert(r == 0);
170
171        if (cap == 0)
172          assert((revents & ~POLLOUT) == 0);
173        else
174          assert((revents & ~POLLIN) == 0);
175
176        avail = snd_pcm_avail(pcm);
177        assert(avail >= 0);
178
179        r = snd_pcm_status(pcm, status);
180        assert(r == 0);
181
182        /* This assertion fails from time to time. ALSA seems to be broken */
183/*         assert(avail == (snd_pcm_sframes_t) snd_pcm_status_get_avail(status)); */
184/*         printf("%lu %lu\n", (unsigned long) avail, (unsigned long) snd_pcm_status_get_avail(status)); */
185
186        snd_pcm_status_get_htstamp(status, &timestamp);
187        delay = snd_pcm_status_get_delay(status);
188        state = snd_pcm_status_get_state(status);
189
190        r = clock_gettime(CLOCK_MONOTONIC, &now);
191        assert(r == 0);
192
193        assert(!revents || avail > 0);
194
195        if ((!cap && (avail >= fillrate)) || (cap && (unsigned)avail >= buffer_size)) {
196            snd_pcm_sframes_t sframes;
197
198            if (cap == 0)
199              sframes = snd_pcm_writei(pcm, samples, fillrate);
200            else
201              sframes = snd_pcm_readi(pcm, samples, fillrate);
202            assert(sframes == fillrate);
203
204            handled = fillrate;
205            sample_count += fillrate;
206        }
207
208        if (!handled &&
209            memcmp(&timestamp, &last_timestamp, sizeof(timestamp)) == 0 &&
210            avail == last_avail &&
211            delay == last_delay) {
212            /* This is boring */
213            continue;
214        }
215
216        now_us = timespec_us(&now);
217        timestamp_us = timespec_us(&timestamp);
218
219        if (cap == 0)
220            pos = (unsigned long long) ((sample_count - handled - delay) * 1000000LU / SAMPLE_RATE);
221        else
222            pos = (unsigned long long) ((sample_count - handled + delay) * 1000000LU / SAMPLE_RATE);
223
224        if (count++ % 50 == 0)
225            printf("Elapsed\tCPU\tALSA\tPos\tSamples\tavail\tdelay\trevents\thandled\tstate\n");
226
227        printf("%llu\t%llu\t%llu\t%llu\t%llu\t%li\t%li\t%i\t%i\t%i\n",
228               (unsigned long long) (now_us - last_us),
229               (unsigned long long) (now_us - start_us),
230               (unsigned long long) (timestamp_us ? timestamp_us - start_us : 0),
231               pos,
232               (unsigned long long) sample_count,
233               (signed long) avail,
234               (signed long) delay,
235               revents,
236               handled,
237               state);
238
239        if (cap == 0)
240          /** When this assert is hit, most likely something bad
241           * happened, i.e. the avail jumped suddenly. */
242          assert((unsigned) avail <= buffer_size);
243
244        last_avail = avail;
245        last_delay = delay;
246        last_timestamp = timestamp;
247        last_us = now_us;
248    }
249
250    return 0;
251}
252