1 /* pcm.c
2 **
3 ** Copyright 2011, The Android Open Source Project
4 **
5 ** Redistribution and use in source and binary forms, with or without
6 ** modification, are permitted provided that the following conditions are met:
7 ** * Redistributions of source code must retain the above copyright
8 ** notice, this list of conditions and the following disclaimer.
9 ** * Redistributions in binary form must reproduce the above copyright
10 ** notice, this list of conditions and the following disclaimer in the
11 ** documentation and/or other materials provided with the distribution.
12 ** * Neither the name of The Android Open Source Project nor the names of
13 ** its contributors may be used to endorse or promote products derived
14 ** from this software without specific prior written permission.
15 **
16 ** THIS SOFTWARE IS PROVIDED BY The Android Open Source Project ``AS IS'' AND
17 ** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 ** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 ** ARE DISCLAIMED. IN NO EVENT SHALL The Android Open Source Project BE LIABLE
20 ** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 ** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 ** SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 ** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
26 ** DAMAGE.
27 */
28
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <fcntl.h>
32 #include <stdarg.h>
33 #include <string.h>
34 #include <errno.h>
35 #include <unistd.h>
36 #include <poll.h>
37
38 #include <sys/ioctl.h>
39 #include <sys/mman.h>
40 #include <sys/time.h>
41 #include <limits.h>
42
43 #include <linux/ioctl.h>
44 #define __force
45 #define __bitwise
46 #define __user
47 #include <sound/asound.h>
48
49 #include <tinyalsa/asoundlib.h>
50
51 #define PARAM_MAX SNDRV_PCM_HW_PARAM_LAST_INTERVAL
52 #define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2)
53
param_is_mask(int p)54 static inline int param_is_mask(int p)
55 {
56 return (p >= SNDRV_PCM_HW_PARAM_FIRST_MASK) &&
57 (p <= SNDRV_PCM_HW_PARAM_LAST_MASK);
58 }
59
param_is_interval(int p)60 static inline int param_is_interval(int p)
61 {
62 return (p >= SNDRV_PCM_HW_PARAM_FIRST_INTERVAL) &&
63 (p <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL);
64 }
65
param_to_interval(struct snd_pcm_hw_params * p,int n)66 static inline struct snd_interval *param_to_interval(struct snd_pcm_hw_params *p, int n)
67 {
68 return &(p->intervals[n - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL]);
69 }
70
param_to_mask(struct snd_pcm_hw_params * p,int n)71 static inline struct snd_mask *param_to_mask(struct snd_pcm_hw_params *p, int n)
72 {
73 return &(p->masks[n - SNDRV_PCM_HW_PARAM_FIRST_MASK]);
74 }
75
param_set_mask(struct snd_pcm_hw_params * p,int n,unsigned int bit)76 static void param_set_mask(struct snd_pcm_hw_params *p, int n, unsigned int bit)
77 {
78 if (bit >= SNDRV_MASK_MAX)
79 return;
80 if (param_is_mask(n)) {
81 struct snd_mask *m = param_to_mask(p, n);
82 m->bits[0] = 0;
83 m->bits[1] = 0;
84 m->bits[bit >> 5] |= (1 << (bit & 31));
85 }
86 }
87
param_set_min(struct snd_pcm_hw_params * p,int n,unsigned int val)88 static void param_set_min(struct snd_pcm_hw_params *p, int n, unsigned int val)
89 {
90 if (param_is_interval(n)) {
91 struct snd_interval *i = param_to_interval(p, n);
92 i->min = val;
93 }
94 }
95
param_set_max(struct snd_pcm_hw_params * p,int n,unsigned int val)96 static void param_set_max(struct snd_pcm_hw_params *p, int n, unsigned int val)
97 {
98 if (param_is_interval(n)) {
99 struct snd_interval *i = param_to_interval(p, n);
100 i->max = val;
101 }
102 }
103
param_set_int(struct snd_pcm_hw_params * p,int n,unsigned int val)104 static void param_set_int(struct snd_pcm_hw_params *p, int n, unsigned int val)
105 {
106 if (param_is_interval(n)) {
107 struct snd_interval *i = param_to_interval(p, n);
108 i->min = val;
109 i->max = val;
110 i->integer = 1;
111 }
112 }
113
param_get_int(struct snd_pcm_hw_params * p,int n)114 static unsigned int param_get_int(struct snd_pcm_hw_params *p, int n)
115 {
116 if (param_is_interval(n)) {
117 struct snd_interval *i = param_to_interval(p, n);
118 if (i->integer)
119 return i->max;
120 }
121 return 0;
122 }
123
param_init(struct snd_pcm_hw_params * p)124 static void param_init(struct snd_pcm_hw_params *p)
125 {
126 int n;
127
128 memset(p, 0, sizeof(*p));
129 for (n = SNDRV_PCM_HW_PARAM_FIRST_MASK;
130 n <= SNDRV_PCM_HW_PARAM_LAST_MASK; n++) {
131 struct snd_mask *m = param_to_mask(p, n);
132 m->bits[0] = ~0;
133 m->bits[1] = ~0;
134 }
135 for (n = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL;
136 n <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; n++) {
137 struct snd_interval *i = param_to_interval(p, n);
138 i->min = 0;
139 i->max = ~0;
140 }
141 }
142
143 #define PCM_ERROR_MAX 128
144
145 struct pcm {
146 int fd;
147 unsigned int flags;
148 int running:1;
149 int underruns;
150 unsigned int buffer_size;
151 unsigned int boundary;
152 char error[PCM_ERROR_MAX];
153 struct pcm_config config;
154 struct snd_pcm_mmap_status *mmap_status;
155 struct snd_pcm_mmap_control *mmap_control;
156 struct snd_pcm_sync_ptr *sync_ptr;
157 void *mmap_buffer;
158 unsigned int noirq_frames_per_msec;
159 int wait_for_avail_min;
160 };
161
pcm_get_buffer_size(struct pcm * pcm)162 unsigned int pcm_get_buffer_size(struct pcm *pcm)
163 {
164 return pcm->buffer_size;
165 }
166
pcm_get_error(struct pcm * pcm)167 const char* pcm_get_error(struct pcm *pcm)
168 {
169 return pcm->error;
170 }
171
oops(struct pcm * pcm,int e,const char * fmt,...)172 static int oops(struct pcm *pcm, int e, const char *fmt, ...)
173 {
174 va_list ap;
175 int sz;
176
177 va_start(ap, fmt);
178 vsnprintf(pcm->error, PCM_ERROR_MAX, fmt, ap);
179 va_end(ap);
180 sz = strlen(pcm->error);
181
182 if (errno)
183 snprintf(pcm->error + sz, PCM_ERROR_MAX - sz,
184 ": %s", strerror(e));
185 return -1;
186 }
187
pcm_format_to_alsa(enum pcm_format format)188 static unsigned int pcm_format_to_alsa(enum pcm_format format)
189 {
190 switch (format) {
191 case PCM_FORMAT_S32_LE:
192 return SNDRV_PCM_FORMAT_S32_LE;
193 default:
194 case PCM_FORMAT_S16_LE:
195 return SNDRV_PCM_FORMAT_S16_LE;
196 };
197 }
198
pcm_format_to_bits(enum pcm_format format)199 static unsigned int pcm_format_to_bits(enum pcm_format format)
200 {
201 switch (format) {
202 case PCM_FORMAT_S32_LE:
203 return 32;
204 default:
205 case PCM_FORMAT_S16_LE:
206 return 16;
207 };
208 }
209
pcm_bytes_to_frames(struct pcm * pcm,unsigned int bytes)210 unsigned int pcm_bytes_to_frames(struct pcm *pcm, unsigned int bytes)
211 {
212 return bytes / (pcm->config.channels *
213 (pcm_format_to_bits(pcm->config.format) >> 3));
214 }
215
pcm_frames_to_bytes(struct pcm * pcm,unsigned int frames)216 unsigned int pcm_frames_to_bytes(struct pcm *pcm, unsigned int frames)
217 {
218 return frames * pcm->config.channels *
219 (pcm_format_to_bits(pcm->config.format) >> 3);
220 }
221
pcm_sync_ptr(struct pcm * pcm,int flags)222 static int pcm_sync_ptr(struct pcm *pcm, int flags) {
223 if (pcm->sync_ptr) {
224 pcm->sync_ptr->flags = flags;
225 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SYNC_PTR, pcm->sync_ptr) < 0)
226 return -1;
227 }
228 return 0;
229 }
230
pcm_hw_mmap_status(struct pcm * pcm)231 static int pcm_hw_mmap_status(struct pcm *pcm) {
232
233 if (pcm->sync_ptr)
234 return 0;
235
236 int page_size = sysconf(_SC_PAGE_SIZE);
237 pcm->mmap_status = mmap(NULL, page_size, PROT_READ, MAP_FILE | MAP_SHARED,
238 pcm->fd, SNDRV_PCM_MMAP_OFFSET_STATUS);
239 if (pcm->mmap_status == MAP_FAILED)
240 pcm->mmap_status = NULL;
241 if (!pcm->mmap_status)
242 goto mmap_error;
243
244 pcm->mmap_control = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
245 MAP_FILE | MAP_SHARED, pcm->fd, SNDRV_PCM_MMAP_OFFSET_CONTROL);
246 if (pcm->mmap_control == MAP_FAILED)
247 pcm->mmap_control = NULL;
248 if (!pcm->mmap_control) {
249 munmap(pcm->mmap_status, page_size);
250 pcm->mmap_status = NULL;
251 goto mmap_error;
252 }
253 if (pcm->flags & PCM_MMAP)
254 pcm->mmap_control->avail_min = pcm->config.avail_min;
255 else
256 pcm->mmap_control->avail_min = 1;
257
258 return 0;
259
260 mmap_error:
261
262 pcm->sync_ptr = calloc(1, sizeof(*pcm->sync_ptr));
263 if (!pcm->sync_ptr)
264 return -ENOMEM;
265 pcm->mmap_status = &pcm->sync_ptr->s.status;
266 pcm->mmap_control = &pcm->sync_ptr->c.control;
267 if (pcm->flags & PCM_MMAP)
268 pcm->mmap_control->avail_min = pcm->config.avail_min;
269 else
270 pcm->mmap_control->avail_min = 1;
271
272 pcm_sync_ptr(pcm, 0);
273
274 return 0;
275 }
276
pcm_hw_munmap_status(struct pcm * pcm)277 static void pcm_hw_munmap_status(struct pcm *pcm) {
278 if (pcm->sync_ptr) {
279 free(pcm->sync_ptr);
280 pcm->sync_ptr = NULL;
281 } else {
282 int page_size = sysconf(_SC_PAGE_SIZE);
283 if (pcm->mmap_status)
284 munmap(pcm->mmap_status, page_size);
285 if (pcm->mmap_control)
286 munmap(pcm->mmap_control, page_size);
287 }
288 pcm->mmap_status = NULL;
289 pcm->mmap_control = NULL;
290 }
291
pcm_areas_copy(struct pcm * pcm,unsigned int pcm_offset,const char * src,unsigned int src_offset,unsigned int frames)292 static int pcm_areas_copy(struct pcm *pcm, unsigned int pcm_offset,
293 const char *src, unsigned int src_offset,
294 unsigned int frames)
295 {
296 int size_bytes = pcm_frames_to_bytes(pcm, frames);
297 int pcm_offset_bytes = pcm_frames_to_bytes(pcm, pcm_offset);
298 int src_offset_bytes = pcm_frames_to_bytes(pcm, src_offset);
299
300 /* interleaved only atm */
301 memcpy((char*)pcm->mmap_buffer + pcm_offset_bytes,
302 src + src_offset_bytes, size_bytes);
303 return 0;
304 }
305
pcm_mmap_write_areas(struct pcm * pcm,const char * src,unsigned int offset,unsigned int size)306 static int pcm_mmap_write_areas(struct pcm *pcm, const char *src,
307 unsigned int offset, unsigned int size)
308 {
309 void *pcm_areas;
310 int commit;
311 unsigned int pcm_offset, frames, count = 0;
312
313 while (size > 0) {
314 frames = size;
315 pcm_mmap_begin(pcm, &pcm_areas, &pcm_offset, &frames);
316 pcm_areas_copy(pcm, pcm_offset, src, offset, frames);
317 commit = pcm_mmap_commit(pcm, pcm_offset, frames);
318 if (commit < 0) {
319 oops(pcm, commit, "failed to commit %d frames\n", frames);
320 return commit;
321 }
322
323 offset += commit;
324 count += commit;
325 size -= commit;
326 }
327 return count;
328 }
329
pcm_get_htimestamp(struct pcm * pcm,unsigned int * avail,struct timespec * tstamp)330 int pcm_get_htimestamp(struct pcm *pcm, unsigned int *avail,
331 struct timespec *tstamp)
332 {
333 int frames;
334 int rc;
335 snd_pcm_uframes_t hw_ptr;
336
337 if (!pcm_is_ready(pcm))
338 return -1;
339
340 rc = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_APPL|SNDRV_PCM_SYNC_PTR_HWSYNC);
341 if (rc < 0)
342 return -1;
343
344 if ((pcm->mmap_status->state != PCM_STATE_RUNNING) &&
345 (pcm->mmap_status->state != PCM_STATE_DRAINING))
346 return -1;
347
348 *tstamp = pcm->mmap_status->tstamp;
349 if (tstamp->tv_sec == 0 && tstamp->tv_nsec == 0)
350 return -1;
351
352 hw_ptr = pcm->mmap_status->hw_ptr;
353 if (pcm->flags & PCM_IN)
354 frames = hw_ptr - pcm->mmap_control->appl_ptr;
355 else
356 frames = hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr;
357
358 if (frames < 0)
359 frames += pcm->boundary;
360 else if (frames > (int)pcm->boundary)
361 frames -= pcm->boundary;
362
363 *avail = (unsigned int)frames;
364
365 return 0;
366 }
367
pcm_write(struct pcm * pcm,const void * data,unsigned int count)368 int pcm_write(struct pcm *pcm, const void *data, unsigned int count)
369 {
370 struct snd_xferi x;
371
372 if (pcm->flags & PCM_IN)
373 return -EINVAL;
374
375 x.buf = (void*)data;
376 x.frames = count / (pcm->config.channels *
377 pcm_format_to_bits(pcm->config.format) / 8);
378
379 for (;;) {
380 if (!pcm->running) {
381 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE))
382 return oops(pcm, errno, "cannot prepare channel");
383 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &x))
384 return oops(pcm, errno, "cannot write initial data");
385 pcm->running = 1;
386 return 0;
387 }
388 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &x)) {
389 pcm->running = 0;
390 if (errno == EPIPE) {
391 /* we failed to make our window -- try to restart if we are
392 * allowed to do so. Otherwise, simply allow the EPIPE error to
393 * propagate up to the app level */
394 pcm->underruns++;
395 if (pcm->flags & PCM_NORESTART)
396 return -EPIPE;
397 continue;
398 }
399 return oops(pcm, errno, "cannot write stream data");
400 }
401 return 0;
402 }
403 }
404
pcm_read(struct pcm * pcm,void * data,unsigned int count)405 int pcm_read(struct pcm *pcm, void *data, unsigned int count)
406 {
407 struct snd_xferi x;
408
409 if (!(pcm->flags & PCM_IN))
410 return -EINVAL;
411
412 x.buf = data;
413 x.frames = count / (pcm->config.channels *
414 pcm_format_to_bits(pcm->config.format) / 8);
415
416 for (;;) {
417 if (!pcm->running) {
418 pcm_start(pcm);
419 }
420 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_READI_FRAMES, &x)) {
421 pcm->running = 0;
422 if (errno == EPIPE) {
423 /* we failed to make our window -- try to restart */
424 pcm->underruns++;
425 continue;
426 }
427 return oops(pcm, errno, "cannot read stream data");
428 }
429 return 0;
430 }
431 }
432
433 static struct pcm bad_pcm = {
434 .fd = -1,
435 };
436
pcm_close(struct pcm * pcm)437 int pcm_close(struct pcm *pcm)
438 {
439 if (pcm == &bad_pcm)
440 return 0;
441
442 pcm_hw_munmap_status(pcm);
443
444 if (pcm->flags & PCM_MMAP) {
445 pcm_stop(pcm);
446 munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
447 }
448
449 if (pcm->fd >= 0)
450 close(pcm->fd);
451 pcm->running = 0;
452 pcm->buffer_size = 0;
453 pcm->fd = -1;
454 free(pcm);
455 return 0;
456 }
457
pcm_open(unsigned int card,unsigned int device,unsigned int flags,struct pcm_config * config)458 struct pcm *pcm_open(unsigned int card, unsigned int device,
459 unsigned int flags, struct pcm_config *config)
460 {
461 struct pcm *pcm;
462 struct snd_pcm_info info;
463 struct snd_pcm_hw_params params;
464 struct snd_pcm_sw_params sparams;
465 char fn[256];
466 int rc;
467
468 pcm = calloc(1, sizeof(struct pcm));
469 if (!pcm || !config)
470 return &bad_pcm; /* TODO: could support default config here */
471
472 pcm->config = *config;
473
474 snprintf(fn, sizeof(fn), "/dev/snd/pcmC%uD%u%c", card, device,
475 flags & PCM_IN ? 'c' : 'p');
476
477 pcm->flags = flags;
478 pcm->fd = open(fn, O_RDWR);
479 if (pcm->fd < 0) {
480 oops(pcm, errno, "cannot open device '%s'", fn);
481 return pcm;
482 }
483
484 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_INFO, &info)) {
485 oops(pcm, errno, "cannot get info");
486 goto fail_close;
487 }
488
489 param_init(¶ms);
490 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_FORMAT,
491 pcm_format_to_alsa(config->format));
492 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_SUBFORMAT,
493 SNDRV_PCM_SUBFORMAT_STD);
494 param_set_min(¶ms, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, config->period_size);
495 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_SAMPLE_BITS,
496 pcm_format_to_bits(config->format));
497 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_FRAME_BITS,
498 pcm_format_to_bits(config->format) * config->channels);
499 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_CHANNELS,
500 config->channels);
501 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_PERIODS, config->period_count);
502 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_RATE, config->rate);
503
504 if (flags & PCM_NOIRQ) {
505
506 if (!(flags & PCM_MMAP)) {
507 oops(pcm, -EINVAL, "noirq only currently supported with mmap().");
508 goto fail;
509 }
510
511 params.flags |= SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP;
512 pcm->noirq_frames_per_msec = config->rate / 1000;
513 }
514
515 if (flags & PCM_MMAP)
516 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_ACCESS,
517 SNDRV_PCM_ACCESS_MMAP_INTERLEAVED);
518 else
519 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_ACCESS,
520 SNDRV_PCM_ACCESS_RW_INTERLEAVED);
521
522 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_HW_PARAMS, ¶ms)) {
523 oops(pcm, errno, "cannot set hw params");
524 goto fail_close;
525 }
526
527 /* get our refined hw_params */
528 config->period_size = param_get_int(¶ms, SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
529 config->period_count = param_get_int(¶ms, SNDRV_PCM_HW_PARAM_PERIODS);
530 pcm->buffer_size = config->period_count * config->period_size;
531
532 if (flags & PCM_MMAP) {
533 pcm->mmap_buffer = mmap(NULL, pcm_frames_to_bytes(pcm, pcm->buffer_size),
534 PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, pcm->fd, 0);
535 if (pcm->mmap_buffer == MAP_FAILED) {
536 oops(pcm, -errno, "failed to mmap buffer %d bytes\n",
537 pcm_frames_to_bytes(pcm, pcm->buffer_size));
538 goto fail_close;
539 }
540 }
541
542
543 memset(&sparams, 0, sizeof(sparams));
544 sparams.tstamp_mode = SNDRV_PCM_TSTAMP_ENABLE;
545 sparams.period_step = 1;
546
547 if (!config->start_threshold)
548 pcm->config.start_threshold = sparams.start_threshold =
549 config->period_count * config->period_size / 2;
550 else
551 sparams.start_threshold = config->start_threshold;
552
553 /* pick a high stop threshold - todo: does this need further tuning */
554 if (!config->stop_threshold) {
555 if (pcm->flags & PCM_IN)
556 pcm->config.stop_threshold = sparams.stop_threshold =
557 config->period_count * config->period_size * 10;
558 else
559 pcm->config.stop_threshold = sparams.stop_threshold =
560 config->period_count * config->period_size;
561 }
562 else
563 sparams.stop_threshold = config->stop_threshold;
564
565 if (!pcm->config.avail_min) {
566 if (pcm->flags & PCM_MMAP)
567 pcm->config.avail_min = sparams.avail_min = pcm->config.period_size;
568 else
569 pcm->config.avail_min = sparams.avail_min = 1;
570 } else
571 sparams.avail_min = config->avail_min;
572
573 sparams.xfer_align = config->period_size / 2; /* needed for old kernels */
574 sparams.silence_size = 0;
575 sparams.silence_threshold = config->silence_threshold;
576 pcm->boundary = sparams.boundary = pcm->buffer_size;
577
578 while (pcm->boundary * 2 <= INT_MAX - pcm->buffer_size)
579 pcm->boundary *= 2;
580
581 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SW_PARAMS, &sparams)) {
582 oops(pcm, errno, "cannot set sw params");
583 goto fail;
584 }
585
586 rc = pcm_hw_mmap_status(pcm);
587 if (rc < 0) {
588 oops(pcm, rc, "mmap status failed");
589 goto fail;
590 }
591
592 pcm->underruns = 0;
593 return pcm;
594
595 fail:
596 if (flags & PCM_MMAP)
597 munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
598 fail_close:
599 close(pcm->fd);
600 pcm->fd = -1;
601 return pcm;
602 }
603
pcm_is_ready(struct pcm * pcm)604 int pcm_is_ready(struct pcm *pcm)
605 {
606 return pcm->fd >= 0;
607 }
608
pcm_start(struct pcm * pcm)609 int pcm_start(struct pcm *pcm)
610 {
611 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE) < 0)
612 return oops(pcm, errno, "cannot prepare channel");
613
614 if (pcm->flags & PCM_MMAP)
615 pcm_sync_ptr(pcm, 0);
616
617 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_START) < 0)
618 return oops(pcm, errno, "cannot start channel");
619
620 pcm->running = 1;
621 return 0;
622 }
623
pcm_stop(struct pcm * pcm)624 int pcm_stop(struct pcm *pcm)
625 {
626 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_DROP) < 0)
627 return oops(pcm, errno, "cannot stop channel");
628
629 pcm->running = 0;
630 return 0;
631 }
632
pcm_mmap_playback_avail(struct pcm * pcm)633 static inline int pcm_mmap_playback_avail(struct pcm *pcm)
634 {
635 int avail;
636
637 avail = pcm->mmap_status->hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr;
638
639 if (avail < 0)
640 avail += pcm->boundary;
641 else if (avail > (int)pcm->boundary)
642 avail -= pcm->boundary;
643
644 return avail;
645 }
646
pcm_mmap_capture_avail(struct pcm * pcm)647 static inline int pcm_mmap_capture_avail(struct pcm *pcm)
648 {
649 int avail = pcm->mmap_status->hw_ptr - pcm->mmap_control->appl_ptr;
650 if (avail < 0)
651 avail += pcm->boundary;
652 return avail;
653 }
654
pcm_mmap_avail(struct pcm * pcm)655 static inline int pcm_mmap_avail(struct pcm *pcm)
656 {
657 pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_HWSYNC);
658 if (pcm->flags & PCM_IN)
659 return pcm_mmap_capture_avail(pcm);
660 else
661 return pcm_mmap_playback_avail(pcm);
662 }
663
pcm_mmap_appl_forward(struct pcm * pcm,int frames)664 static void pcm_mmap_appl_forward(struct pcm *pcm, int frames)
665 {
666 unsigned int appl_ptr = pcm->mmap_control->appl_ptr;
667 appl_ptr += frames;
668
669 /* check for boundary wrap */
670 if (appl_ptr > pcm->boundary)
671 appl_ptr -= pcm->boundary;
672 pcm->mmap_control->appl_ptr = appl_ptr;
673 }
674
pcm_mmap_begin(struct pcm * pcm,void ** areas,unsigned int * offset,unsigned int * frames)675 int pcm_mmap_begin(struct pcm *pcm, void **areas, unsigned int *offset,
676 unsigned int *frames)
677 {
678 unsigned int continuous, copy_frames, avail;
679
680 /* return the mmap buffer */
681 *areas = pcm->mmap_buffer;
682
683 /* and the application offset in frames */
684 *offset = pcm->mmap_control->appl_ptr % pcm->buffer_size;
685
686 avail = pcm_mmap_avail(pcm);
687 if (avail > pcm->buffer_size)
688 avail = pcm->buffer_size;
689 continuous = pcm->buffer_size - *offset;
690
691 /* we can only copy frames if the are availabale and continuos */
692 copy_frames = *frames;
693 if (copy_frames > avail)
694 copy_frames = avail;
695 if (copy_frames > continuous)
696 copy_frames = continuous;
697 *frames = copy_frames;
698
699 return 0;
700 }
701
pcm_mmap_commit(struct pcm * pcm,unsigned int offset,unsigned int frames)702 int pcm_mmap_commit(struct pcm *pcm, unsigned int offset, unsigned int frames)
703 {
704 /* update the application pointer in userspace and kernel */
705 pcm_mmap_appl_forward(pcm, frames);
706 pcm_sync_ptr(pcm, 0);
707
708 return frames;
709 }
710
pcm_avail_update(struct pcm * pcm)711 int pcm_avail_update(struct pcm *pcm)
712 {
713 pcm_sync_ptr(pcm, 0);
714 return pcm_mmap_avail(pcm);
715 }
716
pcm_state(struct pcm * pcm)717 int pcm_state(struct pcm *pcm)
718 {
719 int err = pcm_sync_ptr(pcm, 0);
720 if (err < 0)
721 return err;
722
723 return pcm->mmap_status->state;
724 }
725
pcm_set_avail_min(struct pcm * pcm,int avail_min)726 int pcm_set_avail_min(struct pcm *pcm, int avail_min)
727 {
728 if ((~pcm->flags) & (PCM_MMAP | PCM_NOIRQ))
729 return -ENOSYS;
730
731 pcm->config.avail_min = avail_min;
732 return 0;
733 }
734
pcm_wait(struct pcm * pcm,int timeout)735 int pcm_wait(struct pcm *pcm, int timeout)
736 {
737 struct pollfd pfd;
738 unsigned short revents = 0;
739 int err;
740
741 pfd.fd = pcm->fd;
742 pfd.events = POLLOUT | POLLERR | POLLNVAL;
743
744 do {
745 /* let's wait for avail or timeout */
746 err = poll(&pfd, 1, timeout);
747 if (err < 0)
748 return -errno;
749
750 /* timeout ? */
751 if (err == 0)
752 return 0;
753
754 /* have we been interrupted ? */
755 if (errno == -EINTR)
756 continue;
757
758 /* check for any errors */
759 if (pfd.revents & (POLLERR | POLLNVAL)) {
760 switch (pcm_state(pcm)) {
761 case PCM_STATE_XRUN:
762 return -EPIPE;
763 case PCM_STATE_SUSPENDED:
764 return -ESTRPIPE;
765 case PCM_STATE_DISCONNECTED:
766 return -ENODEV;
767 default:
768 return -EIO;
769 }
770 }
771 /* poll again if fd not ready for IO */
772 } while (!(pfd.revents & (POLLIN | POLLOUT)));
773
774 return 1;
775 }
776
pcm_mmap_write(struct pcm * pcm,const void * buffer,unsigned int bytes)777 int pcm_mmap_write(struct pcm *pcm, const void *buffer, unsigned int bytes)
778 {
779 int err = 0, frames, avail;
780 unsigned int offset = 0, count;
781
782 if (bytes == 0)
783 return 0;
784
785 count = pcm_bytes_to_frames(pcm, bytes);
786
787 while (count > 0) {
788
789 /* get the available space for writing new frames */
790 avail = pcm_avail_update(pcm);
791 if (avail < 0) {
792 fprintf(stderr, "cannot determine available mmap frames");
793 return err;
794 }
795
796 /* start the audio if we reach the threshold */
797 if (!pcm->running &&
798 (pcm->buffer_size - avail) >= pcm->config.start_threshold) {
799 if (pcm_start(pcm) < 0) {
800 fprintf(stderr, "start error: hw 0x%x app 0x%x avail 0x%x\n",
801 (unsigned int)pcm->mmap_status->hw_ptr,
802 (unsigned int)pcm->mmap_control->appl_ptr,
803 avail);
804 return -errno;
805 }
806 pcm->wait_for_avail_min = 0;
807 }
808
809 /* sleep until we have space to write new frames */
810 if (pcm->running) {
811 /* enable waiting for avail_min threshold when less frames than we have to write
812 * are available. */
813 if (!pcm->wait_for_avail_min && (count > (unsigned int)avail))
814 pcm->wait_for_avail_min = 1;
815
816 if (pcm->wait_for_avail_min && (avail < pcm->config.avail_min)) {
817 int time = -1;
818
819 /* disable waiting for avail_min threshold to allow small amounts of data to be
820 * written without waiting as long as there is enough room in buffer. */
821 pcm->wait_for_avail_min = 0;
822
823 if (pcm->flags & PCM_NOIRQ)
824 time = (pcm->config.avail_min - avail) / pcm->noirq_frames_per_msec;
825
826 err = pcm_wait(pcm, time);
827 if (err < 0) {
828 pcm->running = 0;
829 oops(pcm, err, "wait error: hw 0x%x app 0x%x avail 0x%x\n",
830 (unsigned int)pcm->mmap_status->hw_ptr,
831 (unsigned int)pcm->mmap_control->appl_ptr,
832 avail);
833 pcm->mmap_control->appl_ptr = 0;
834 return err;
835 }
836 continue;
837 }
838 }
839
840 frames = count;
841 if (frames > avail)
842 frames = avail;
843
844 if (!frames)
845 break;
846
847 /* copy frames from buffer */
848 frames = pcm_mmap_write_areas(pcm, buffer, offset, frames);
849 if (frames < 0) {
850 fprintf(stderr, "write error: hw 0x%x app 0x%x avail 0x%x\n",
851 (unsigned int)pcm->mmap_status->hw_ptr,
852 (unsigned int)pcm->mmap_control->appl_ptr,
853 avail);
854 return frames;
855 }
856
857 offset += frames;
858 count -= frames;
859 }
860
861 _end:
862 return 0;
863 }
864