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,char * src,unsigned int offset,unsigned int size)306 static int pcm_mmap_write_areas(struct pcm *pcm, 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 *tstamp = pcm->mmap_status->tstamp;
345 if (tstamp->tv_sec == 0 && tstamp->tv_nsec == 0)
346 return -1;
347
348 hw_ptr = pcm->mmap_status->hw_ptr;
349 if (pcm->flags & PCM_IN)
350 frames = hw_ptr - pcm->mmap_control->appl_ptr;
351 else
352 frames = hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr;
353
354 if (frames < 0)
355 frames += pcm->boundary;
356 else if (frames > (int)pcm->boundary)
357 frames -= pcm->boundary;
358
359 *avail = (unsigned int)frames;
360
361 return 0;
362 }
363
pcm_write(struct pcm * pcm,void * data,unsigned int count)364 int pcm_write(struct pcm *pcm, void *data, unsigned int count)
365 {
366 struct snd_xferi x;
367
368 if (pcm->flags & PCM_IN)
369 return -EINVAL;
370
371 x.buf = data;
372 x.frames = count / (pcm->config.channels *
373 pcm_format_to_bits(pcm->config.format) / 8);
374
375 for (;;) {
376 if (!pcm->running) {
377 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE))
378 return oops(pcm, errno, "cannot prepare channel");
379 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &x))
380 return oops(pcm, errno, "cannot write initial data");
381 pcm->running = 1;
382 return 0;
383 }
384 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &x)) {
385 pcm->running = 0;
386 if (errno == EPIPE) {
387 /* we failed to make our window -- try to restart */
388 pcm->underruns++;
389 continue;
390 }
391 return oops(pcm, errno, "cannot write stream data");
392 }
393 return 0;
394 }
395 }
396
pcm_read(struct pcm * pcm,void * data,unsigned int count)397 int pcm_read(struct pcm *pcm, void *data, unsigned int count)
398 {
399 struct snd_xferi x;
400
401 if (!(pcm->flags & PCM_IN))
402 return -EINVAL;
403
404 x.buf = data;
405 x.frames = count / (pcm->config.channels *
406 pcm_format_to_bits(pcm->config.format) / 8);
407
408 for (;;) {
409 if (!pcm->running) {
410 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE))
411 return oops(pcm, errno, "cannot prepare channel");
412 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_START))
413 return oops(pcm, errno, "cannot start channel");
414 pcm->running = 1;
415 }
416 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_READI_FRAMES, &x)) {
417 pcm->running = 0;
418 if (errno == EPIPE) {
419 /* we failed to make our window -- try to restart */
420 pcm->underruns++;
421 continue;
422 }
423 return oops(pcm, errno, "cannot read stream data");
424 }
425 return 0;
426 }
427 }
428
429 static struct pcm bad_pcm = {
430 .fd = -1,
431 };
432
pcm_close(struct pcm * pcm)433 int pcm_close(struct pcm *pcm)
434 {
435 if (pcm == &bad_pcm)
436 return 0;
437
438 pcm_hw_munmap_status(pcm);
439
440 if (pcm->flags & PCM_MMAP) {
441 pcm_stop(pcm);
442 munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
443 }
444
445 if (pcm->fd >= 0)
446 close(pcm->fd);
447 pcm->running = 0;
448 pcm->buffer_size = 0;
449 pcm->fd = -1;
450 free(pcm);
451 return 0;
452 }
453
pcm_open(unsigned int card,unsigned int device,unsigned int flags,struct pcm_config * config)454 struct pcm *pcm_open(unsigned int card, unsigned int device,
455 unsigned int flags, struct pcm_config *config)
456 {
457 struct pcm *pcm;
458 struct snd_pcm_info info;
459 struct snd_pcm_hw_params params;
460 struct snd_pcm_sw_params sparams;
461 char fn[256];
462 int rc;
463
464 pcm = calloc(1, sizeof(struct pcm));
465 if (!pcm || !config)
466 return &bad_pcm; /* TODO: could support default config here */
467
468 pcm->config = *config;
469
470 snprintf(fn, sizeof(fn), "/dev/snd/pcmC%uD%u%c", card, device,
471 flags & PCM_IN ? 'c' : 'p');
472
473 pcm->flags = flags;
474 pcm->fd = open(fn, O_RDWR);
475 if (pcm->fd < 0) {
476 oops(pcm, errno, "cannot open device '%s'", fn);
477 return pcm;
478 }
479
480 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_INFO, &info)) {
481 oops(pcm, errno, "cannot get info");
482 goto fail_close;
483 }
484
485 param_init(¶ms);
486 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_FORMAT,
487 pcm_format_to_alsa(config->format));
488 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_SUBFORMAT,
489 SNDRV_PCM_SUBFORMAT_STD);
490 param_set_min(¶ms, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, config->period_size);
491 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_SAMPLE_BITS,
492 pcm_format_to_bits(config->format));
493 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_FRAME_BITS,
494 pcm_format_to_bits(config->format) * config->channels);
495 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_CHANNELS,
496 config->channels);
497 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_PERIODS, config->period_count);
498 param_set_int(¶ms, SNDRV_PCM_HW_PARAM_RATE, config->rate);
499
500 if (flags & PCM_NOIRQ) {
501
502 if (!(flags & PCM_MMAP)) {
503 oops(pcm, -EINVAL, "noirq only currently supported with mmap().");
504 goto fail;
505 }
506
507 params.flags |= SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP;
508 pcm->noirq_frames_per_msec = config->rate / 1000;
509 }
510
511 if (flags & PCM_MMAP)
512 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_ACCESS,
513 SNDRV_PCM_ACCESS_MMAP_INTERLEAVED);
514 else
515 param_set_mask(¶ms, SNDRV_PCM_HW_PARAM_ACCESS,
516 SNDRV_PCM_ACCESS_RW_INTERLEAVED);
517
518 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_HW_PARAMS, ¶ms)) {
519 oops(pcm, errno, "cannot set hw params");
520 goto fail_close;
521 }
522
523 /* get our refined hw_params */
524 config->period_size = param_get_int(¶ms, SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
525 config->period_count = param_get_int(¶ms, SNDRV_PCM_HW_PARAM_PERIODS);
526 pcm->buffer_size = config->period_count * config->period_size;
527
528 if (flags & PCM_MMAP) {
529 pcm->mmap_buffer = mmap(NULL, pcm_frames_to_bytes(pcm, pcm->buffer_size),
530 PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, pcm->fd, 0);
531 if (pcm->mmap_buffer == MAP_FAILED) {
532 oops(pcm, -errno, "failed to mmap buffer %d bytes\n",
533 pcm_frames_to_bytes(pcm, pcm->buffer_size));
534 goto fail_close;
535 }
536 }
537
538
539 memset(&sparams, 0, sizeof(sparams));
540 sparams.tstamp_mode = SNDRV_PCM_TSTAMP_ENABLE;
541 sparams.period_step = 1;
542
543 if (!config->start_threshold)
544 pcm->config.start_threshold = sparams.start_threshold =
545 config->period_count * config->period_size / 2;
546 else
547 sparams.start_threshold = config->start_threshold;
548
549 /* pick a high stop threshold - todo: does this need further tuning */
550 if (!config->stop_threshold)
551 pcm->config.stop_threshold = sparams.stop_threshold =
552 config->period_count * config->period_size * 10;
553 else
554 sparams.stop_threshold = config->stop_threshold;
555
556 if (!pcm->config.avail_min) {
557 if (pcm->flags & PCM_MMAP)
558 pcm->config.avail_min = sparams.avail_min = pcm->config.period_size;
559 else
560 pcm->config.avail_min = sparams.avail_min = 1;
561 } else
562 sparams.avail_min = config->avail_min;
563
564 sparams.xfer_align = config->period_size / 2; /* needed for old kernels */
565 sparams.silence_size = 0;
566 sparams.silence_threshold = config->silence_threshold;
567 pcm->boundary = sparams.boundary = pcm->buffer_size;
568
569 while (pcm->boundary * 2 <= LONG_MAX - pcm->buffer_size)
570 pcm->boundary *= 2;
571
572 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SW_PARAMS, &sparams)) {
573 oops(pcm, errno, "cannot set sw params");
574 goto fail;
575 }
576
577 rc = pcm_hw_mmap_status(pcm);
578 if (rc < 0) {
579 oops(pcm, rc, "mmap status failed");
580 goto fail;
581 }
582
583 pcm->underruns = 0;
584 return pcm;
585
586 fail:
587 if (flags & PCM_MMAP)
588 munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
589 fail_close:
590 close(pcm->fd);
591 pcm->fd = -1;
592 return pcm;
593 }
594
pcm_is_ready(struct pcm * pcm)595 int pcm_is_ready(struct pcm *pcm)
596 {
597 return pcm->fd >= 0;
598 }
599
pcm_start(struct pcm * pcm)600 int pcm_start(struct pcm *pcm)
601 {
602 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE) < 0)
603 return oops(pcm, errno, "cannot prepare channel");
604
605 if (pcm->flags & PCM_MMAP)
606 pcm_sync_ptr(pcm, 0);
607
608 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_START) < 0)
609 return oops(pcm, errno, "cannot start channel");
610
611 pcm->running = 1;
612 return 0;
613 }
614
pcm_stop(struct pcm * pcm)615 int pcm_stop(struct pcm *pcm)
616 {
617 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_DROP) < 0)
618 return oops(pcm, errno, "cannot stop channel");
619
620 pcm->running = 0;
621 return 0;
622 }
623
pcm_mmap_playback_avail(struct pcm * pcm)624 static inline int pcm_mmap_playback_avail(struct pcm *pcm)
625 {
626 int avail;
627
628 avail = pcm->mmap_status->hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr;
629
630 if (avail < 0)
631 avail += pcm->boundary;
632 else if (avail > (int)pcm->boundary)
633 avail -= pcm->boundary;
634
635 return avail;
636 }
637
pcm_mmap_capture_avail(struct pcm * pcm)638 static inline int pcm_mmap_capture_avail(struct pcm *pcm)
639 {
640 int avail = pcm->mmap_status->hw_ptr - pcm->mmap_control->appl_ptr;
641 if (avail < 0)
642 avail += pcm->boundary;
643 return avail;
644 }
645
pcm_mmap_avail(struct pcm * pcm)646 static inline int pcm_mmap_avail(struct pcm *pcm)
647 {
648 pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_HWSYNC);
649 if (pcm->flags & PCM_IN)
650 return pcm_mmap_capture_avail(pcm);
651 else
652 return pcm_mmap_playback_avail(pcm);
653 }
654
pcm_mmap_appl_forward(struct pcm * pcm,int frames)655 static void pcm_mmap_appl_forward(struct pcm *pcm, int frames)
656 {
657 unsigned int appl_ptr = pcm->mmap_control->appl_ptr;
658 appl_ptr += frames;
659
660 /* check for boundary wrap */
661 if (appl_ptr > pcm->boundary)
662 appl_ptr -= pcm->boundary;
663 pcm->mmap_control->appl_ptr = appl_ptr;
664 }
665
pcm_mmap_begin(struct pcm * pcm,void ** areas,unsigned int * offset,unsigned int * frames)666 int pcm_mmap_begin(struct pcm *pcm, void **areas, unsigned int *offset,
667 unsigned int *frames)
668 {
669 unsigned int continuous, copy_frames, avail;
670
671 /* return the mmap buffer */
672 *areas = pcm->mmap_buffer;
673
674 /* and the application offset in frames */
675 *offset = pcm->mmap_control->appl_ptr % pcm->buffer_size;
676
677 avail = pcm_mmap_avail(pcm);
678 if (avail > pcm->buffer_size)
679 avail = pcm->buffer_size;
680 continuous = pcm->buffer_size - *offset;
681
682 /* we can only copy frames if the are availabale and continuos */
683 copy_frames = *frames;
684 if (copy_frames > avail)
685 copy_frames = avail;
686 if (copy_frames > continuous)
687 copy_frames = continuous;
688 *frames = copy_frames;
689
690 return 0;
691 }
692
pcm_mmap_commit(struct pcm * pcm,unsigned int offset,unsigned int frames)693 int pcm_mmap_commit(struct pcm *pcm, unsigned int offset, unsigned int frames)
694 {
695 /* update the application pointer in userspace and kernel */
696 pcm_mmap_appl_forward(pcm, frames);
697 pcm_sync_ptr(pcm, 0);
698
699 return frames;
700 }
701
pcm_avail_update(struct pcm * pcm)702 int pcm_avail_update(struct pcm *pcm)
703 {
704 pcm_sync_ptr(pcm, 0);
705 return pcm_mmap_avail(pcm);
706 }
707
pcm_state(struct pcm * pcm)708 int pcm_state(struct pcm *pcm)
709 {
710 int err = pcm_sync_ptr(pcm, 0);
711 if (err < 0)
712 return err;
713
714 return pcm->mmap_status->state;
715 }
716
pcm_set_avail_min(struct pcm * pcm,int avail_min)717 int pcm_set_avail_min(struct pcm *pcm, int avail_min)
718 {
719 if ((~pcm->flags) & (PCM_MMAP | PCM_NOIRQ))
720 return -ENOSYS;
721
722 pcm->config.avail_min = avail_min;
723 return 0;
724 }
725
pcm_wait(struct pcm * pcm,int timeout)726 int pcm_wait(struct pcm *pcm, int timeout)
727 {
728 struct pollfd pfd;
729 unsigned short revents = 0;
730 int err;
731
732 pfd.fd = pcm->fd;
733 pfd.events = POLLOUT | POLLERR | POLLNVAL;
734
735 do {
736 /* let's wait for avail or timeout */
737 err = poll(&pfd, 1, timeout);
738 if (err < 0)
739 return -errno;
740
741 /* timeout ? */
742 if (err == 0)
743 return 0;
744
745 /* have we been interrupted ? */
746 if (errno == -EINTR)
747 continue;
748
749 /* check for any errors */
750 if (pfd.revents & (POLLERR | POLLNVAL)) {
751 switch (pcm_state(pcm)) {
752 case PCM_STATE_XRUN:
753 return -EPIPE;
754 case PCM_STATE_SUSPENDED:
755 return -ESTRPIPE;
756 case PCM_STATE_DISCONNECTED:
757 return -ENODEV;
758 default:
759 return -EIO;
760 }
761 }
762 /* poll again if fd not ready for IO */
763 } while (!(pfd.revents & (POLLIN | POLLOUT)));
764
765 return 1;
766 }
767
pcm_mmap_write(struct pcm * pcm,void * buffer,unsigned int bytes)768 int pcm_mmap_write(struct pcm *pcm, void *buffer, unsigned int bytes)
769 {
770 int err = 0, frames, avail;
771 unsigned int offset = 0, count;
772
773 if (bytes == 0)
774 return 0;
775
776 count = pcm_bytes_to_frames(pcm, bytes);
777
778 while (count > 0) {
779
780 /* get the available space for writing new frames */
781 avail = pcm_avail_update(pcm);
782 if (avail < 0) {
783 fprintf(stderr, "cannot determine available mmap frames");
784 return err;
785 }
786
787 /* start the audio if we reach the threshold */
788 if (!pcm->running &&
789 (pcm->buffer_size - avail) >= pcm->config.start_threshold) {
790 if (pcm_start(pcm) < 0) {
791 fprintf(stderr, "start error: hw 0x%x app 0x%x avail 0x%x\n",
792 (unsigned int)pcm->mmap_status->hw_ptr,
793 (unsigned int)pcm->mmap_control->appl_ptr,
794 avail);
795 return -errno;
796 }
797 pcm->wait_for_avail_min = 0;
798 }
799
800 /* sleep until we have space to write new frames */
801 if (pcm->running) {
802 /* enable waiting for avail_min threshold when less frames than we have to write
803 * are available. */
804 if (!pcm->wait_for_avail_min && (count > (unsigned int)avail))
805 pcm->wait_for_avail_min = 1;
806
807 if (pcm->wait_for_avail_min && (avail < pcm->config.avail_min)) {
808 int time = -1;
809
810 /* disable waiting for avail_min threshold to allow small amounts of data to be
811 * written without waiting as long as there is enough room in buffer. */
812 pcm->wait_for_avail_min = 0;
813
814 if (pcm->flags & PCM_NOIRQ)
815 time = (pcm->config.avail_min - avail) / pcm->noirq_frames_per_msec;
816
817 err = pcm_wait(pcm, time);
818 if (err < 0) {
819 pcm->running = 0;
820 oops(pcm, err, "wait error: hw 0x%x app 0x%x avail 0x%x\n",
821 (unsigned int)pcm->mmap_status->hw_ptr,
822 (unsigned int)pcm->mmap_control->appl_ptr,
823 avail);
824 pcm->mmap_control->appl_ptr = 0;
825 return err;
826 }
827 continue;
828 }
829 }
830
831 frames = count;
832 if (frames > avail)
833 frames = avail;
834
835 if (!frames)
836 break;
837
838 /* copy frames from buffer */
839 frames = pcm_mmap_write_areas(pcm, buffer, offset, frames);
840 if (frames < 0) {
841 fprintf(stderr, "write error: hw 0x%x app 0x%x avail 0x%x\n",
842 (unsigned int)pcm->mmap_status->hw_ptr,
843 (unsigned int)pcm->mmap_control->appl_ptr,
844 avail);
845 return frames;
846 }
847
848 offset += frames;
849 count -= frames;
850 }
851
852 _end:
853 return 0;
854 }
855