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 */
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>
38 #include <sys/ioctl.h>
39 #include <sys/mman.h>
40 #include <sys/time.h>
41 #include <limits.h>
43 #include <linux/ioctl.h>
44 #define __force
45 #define __bitwise
46 #define __user
47 #include <sound/asound.h>
49 #include <tinyalsa/asoundlib.h>
51 #define PARAM_MAX SNDRV_PCM_HW_PARAM_LAST_INTERVAL
52 #define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2)
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 }
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 }
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 }
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 }
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 }
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 }
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 }
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 }
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 }
124 static void param_init(struct snd_pcm_hw_params *p)
125 {
126 int n;
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 }
143 #define PCM_ERROR_MAX 128
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 };
162 unsigned int pcm_get_buffer_size(struct pcm *pcm)
163 {
164 return pcm->buffer_size;
165 }
167 const char* pcm_get_error(struct pcm *pcm)
168 {
169 return pcm->error;
170 }
172 static int oops(struct pcm *pcm, int e, const char *fmt, ...)
173 {
174 va_list ap;
175 int sz;
177 va_start(ap, fmt);
178 vsnprintf(pcm->error, PCM_ERROR_MAX, fmt, ap);
179 va_end(ap);
180 sz = strlen(pcm->error);
182 if (errno)
183 snprintf(pcm->error + sz, PCM_ERROR_MAX - sz,
184 ": %s", strerror(e));
185 return -1;
186 }
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 }
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 }
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 }
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 }
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 }
231 static int pcm_hw_mmap_status(struct pcm *pcm) {
233 if (pcm->sync_ptr)
234 return 0;
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;
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;
258 return 0;
260 mmap_error:
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;
272 pcm_sync_ptr(pcm, 0);
274 return 0;
275 }
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 }
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);
300 /* interleaved only atm */
301 memcpy((char*)pcm->mmap_buffer + pcm_offset_bytes,
302 src + src_offset_bytes, size_bytes);
303 return 0;
304 }
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;
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 }
323 offset += commit;
324 count += commit;
325 size -= commit;
326 }
327 return count;
328 }
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;
337 if (!pcm_is_ready(pcm))
338 return -1;
340 rc = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_APPL|SNDRV_PCM_SYNC_PTR_HWSYNC);
341 if (rc < 0)
342 return -1;
344 if ((pcm->mmap_status->state != PCM_STATE_RUNNING) &&
345 (pcm->mmap_status->state != PCM_STATE_DRAINING))
346 return -1;
348 *tstamp = pcm->mmap_status->tstamp;
349 if (tstamp->tv_sec == 0 && tstamp->tv_nsec == 0)
350 return -1;
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;
358 if (frames < 0)
359 frames += pcm->boundary;
360 else if (frames > (int)pcm->boundary)
361 frames -= pcm->boundary;
363 *avail = (unsigned int)frames;
365 return 0;
366 }
368 int pcm_write(struct pcm *pcm, const void *data, unsigned int count)
369 {
370 struct snd_xferi x;
372 if (pcm->flags & PCM_IN)
373 return -EINVAL;
375 x.buf = (void*)data;
376 x.frames = count / (pcm->config.channels *
377 pcm_format_to_bits(pcm->config.format) / 8);
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 */
392 pcm->underruns++;
393 continue;
394 }
395 return oops(pcm, errno, "cannot write stream data");
396 }
397 return 0;
398 }
399 }
401 int pcm_read(struct pcm *pcm, void *data, unsigned int count)
402 {
403 struct snd_xferi x;
405 if (!(pcm->flags & PCM_IN))
406 return -EINVAL;
408 x.buf = data;
409 x.frames = count / (pcm->config.channels *
410 pcm_format_to_bits(pcm->config.format) / 8);
412 for (;;) {
413 if (!pcm->running) {
414 pcm_start(pcm);
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 }
429 static struct pcm bad_pcm = {
430 .fd = -1,
431 };
433 int pcm_close(struct pcm *pcm)
434 {
435 if (pcm == &bad_pcm)
436 return 0;
438 pcm_hw_munmap_status(pcm);
440 if (pcm->flags & PCM_MMAP) {
441 pcm_stop(pcm);
442 munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
443 }
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 }
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;
464 pcm = calloc(1, sizeof(struct pcm));
465 if (!pcm || !config)
466 return &bad_pcm; /* TODO: could support default config here */
468 pcm->config = *config;
470 snprintf(fn, sizeof(fn), "/dev/snd/pcmC%uD%u%c", card, device,
471 flags & PCM_IN ? 'c' : 'p');
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 }
480 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_INFO, &info)) {
481 oops(pcm, errno, "cannot get info");
482 goto fail_close;
483 }
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);
500 if (flags & PCM_NOIRQ) {
502 if (!(flags & PCM_MMAP)) {
503 oops(pcm, -EINVAL, "noirq only currently supported with mmap().");
504 goto fail;
505 }
507 params.flags |= SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP;
508 pcm->noirq_frames_per_msec = config->rate / 1000;
509 }
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);
518 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_HW_PARAMS, ¶ms)) {
519 oops(pcm, errno, "cannot set hw params");
520 goto fail_close;
521 }
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;
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 }
539 memset(&sparams, 0, sizeof(sparams));
540 sparams.tstamp_mode = SNDRV_PCM_TSTAMP_ENABLE;
541 sparams.period_step = 1;
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;
549 /* pick a high stop threshold - todo: does this need further tuning */
550 if (!config->stop_threshold) {
551 if (pcm->flags & PCM_IN)
552 pcm->config.stop_threshold = sparams.stop_threshold =
553 config->period_count * config->period_size * 10;
554 else
555 pcm->config.stop_threshold = sparams.stop_threshold =
556 config->period_count * config->period_size;
557 }
558 else
559 sparams.stop_threshold = config->stop_threshold;
561 if (!pcm->config.avail_min) {
562 if (pcm->flags & PCM_MMAP)
563 pcm->config.avail_min = sparams.avail_min = pcm->config.period_size;
564 else
565 pcm->config.avail_min = sparams.avail_min = 1;
566 } else
567 sparams.avail_min = config->avail_min;
569 sparams.xfer_align = config->period_size / 2; /* needed for old kernels */
570 sparams.silence_size = 0;
571 sparams.silence_threshold = config->silence_threshold;
572 pcm->boundary = sparams.boundary = pcm->buffer_size;
574 while (pcm->boundary * 2 <= INT_MAX - pcm->buffer_size)
575 pcm->boundary *= 2;
577 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SW_PARAMS, &sparams)) {
578 oops(pcm, errno, "cannot set sw params");
579 goto fail;
580 }
582 rc = pcm_hw_mmap_status(pcm);
583 if (rc < 0) {
584 oops(pcm, rc, "mmap status failed");
585 goto fail;
586 }
588 pcm->underruns = 0;
589 return pcm;
591 fail:
592 if (flags & PCM_MMAP)
593 munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
594 fail_close:
595 close(pcm->fd);
596 pcm->fd = -1;
597 return pcm;
598 }
600 int pcm_is_ready(struct pcm *pcm)
601 {
602 return pcm->fd >= 0;
603 }
605 int pcm_start(struct pcm *pcm)
606 {
607 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE) < 0)
608 return oops(pcm, errno, "cannot prepare channel");
610 if (pcm->flags & PCM_MMAP)
611 pcm_sync_ptr(pcm, 0);
613 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_START) < 0)
614 return oops(pcm, errno, "cannot start channel");
616 pcm->running = 1;
617 return 0;
618 }
620 int pcm_stop(struct pcm *pcm)
621 {
622 if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_DROP) < 0)
623 return oops(pcm, errno, "cannot stop channel");
625 pcm->running = 0;
626 return 0;
627 }
629 static inline int pcm_mmap_playback_avail(struct pcm *pcm)
630 {
631 int avail;
633 avail = pcm->mmap_status->hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr;
635 if (avail < 0)
636 avail += pcm->boundary;
637 else if (avail > (int)pcm->boundary)
638 avail -= pcm->boundary;
640 return avail;
641 }
643 static inline int pcm_mmap_capture_avail(struct pcm *pcm)
644 {
645 int avail = pcm->mmap_status->hw_ptr - pcm->mmap_control->appl_ptr;
646 if (avail < 0)
647 avail += pcm->boundary;
648 return avail;
649 }
651 static inline int pcm_mmap_avail(struct pcm *pcm)
652 {
653 pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_HWSYNC);
654 if (pcm->flags & PCM_IN)
655 return pcm_mmap_capture_avail(pcm);
656 else
657 return pcm_mmap_playback_avail(pcm);
658 }
660 static void pcm_mmap_appl_forward(struct pcm *pcm, int frames)
661 {
662 unsigned int appl_ptr = pcm->mmap_control->appl_ptr;
663 appl_ptr += frames;
665 /* check for boundary wrap */
666 if (appl_ptr > pcm->boundary)
667 appl_ptr -= pcm->boundary;
668 pcm->mmap_control->appl_ptr = appl_ptr;
669 }
671 int pcm_mmap_begin(struct pcm *pcm, void **areas, unsigned int *offset,
672 unsigned int *frames)
673 {
674 unsigned int continuous, copy_frames, avail;
676 /* return the mmap buffer */
677 *areas = pcm->mmap_buffer;
679 /* and the application offset in frames */
680 *offset = pcm->mmap_control->appl_ptr % pcm->buffer_size;
682 avail = pcm_mmap_avail(pcm);
683 if (avail > pcm->buffer_size)
684 avail = pcm->buffer_size;
685 continuous = pcm->buffer_size - *offset;
687 /* we can only copy frames if the are availabale and continuos */
688 copy_frames = *frames;
689 if (copy_frames > avail)
690 copy_frames = avail;
691 if (copy_frames > continuous)
692 copy_frames = continuous;
693 *frames = copy_frames;
695 return 0;
696 }
698 int pcm_mmap_commit(struct pcm *pcm, unsigned int offset, unsigned int frames)
699 {
700 /* update the application pointer in userspace and kernel */
701 pcm_mmap_appl_forward(pcm, frames);
702 pcm_sync_ptr(pcm, 0);
704 return frames;
705 }
707 int pcm_avail_update(struct pcm *pcm)
708 {
709 pcm_sync_ptr(pcm, 0);
710 return pcm_mmap_avail(pcm);
711 }
713 int pcm_state(struct pcm *pcm)
714 {
715 int err = pcm_sync_ptr(pcm, 0);
716 if (err < 0)
717 return err;
719 return pcm->mmap_status->state;
720 }
722 int pcm_set_avail_min(struct pcm *pcm, int avail_min)
723 {
724 if ((~pcm->flags) & (PCM_MMAP | PCM_NOIRQ))
725 return -ENOSYS;
727 pcm->config.avail_min = avail_min;
728 return 0;
729 }
731 int pcm_wait(struct pcm *pcm, int timeout)
732 {
733 struct pollfd pfd;
734 unsigned short revents = 0;
735 int err;
737 pfd.fd = pcm->fd;
738 pfd.events = POLLOUT | POLLERR | POLLNVAL;
740 do {
741 /* let's wait for avail or timeout */
742 err = poll(&pfd, 1, timeout);
743 if (err < 0)
744 return -errno;
746 /* timeout ? */
747 if (err == 0)
748 return 0;
750 /* have we been interrupted ? */
751 if (errno == -EINTR)
752 continue;
754 /* check for any errors */
755 if (pfd.revents & (POLLERR | POLLNVAL)) {
756 switch (pcm_state(pcm)) {
757 case PCM_STATE_XRUN:
758 return -EPIPE;
759 case PCM_STATE_SUSPENDED:
760 return -ESTRPIPE;
761 case PCM_STATE_DISCONNECTED:
762 return -ENODEV;
763 default:
764 return -EIO;
765 }
766 }
767 /* poll again if fd not ready for IO */
768 } while (!(pfd.revents & (POLLIN | POLLOUT)));
770 return 1;
771 }
773 int pcm_mmap_write(struct pcm *pcm, const void *buffer, unsigned int bytes)
774 {
775 int err = 0, frames, avail;
776 unsigned int offset = 0, count;
778 if (bytes == 0)
779 return 0;
781 count = pcm_bytes_to_frames(pcm, bytes);
783 while (count > 0) {
785 /* get the available space for writing new frames */
786 avail = pcm_avail_update(pcm);
787 if (avail < 0) {
788 fprintf(stderr, "cannot determine available mmap frames");
789 return err;
790 }
792 /* start the audio if we reach the threshold */
793 if (!pcm->running &&
794 (pcm->buffer_size - avail) >= pcm->config.start_threshold) {
795 if (pcm_start(pcm) < 0) {
796 fprintf(stderr, "start error: hw 0x%x app 0x%x avail 0x%x\n",
797 (unsigned int)pcm->mmap_status->hw_ptr,
798 (unsigned int)pcm->mmap_control->appl_ptr,
799 avail);
800 return -errno;
801 }
802 pcm->wait_for_avail_min = 0;
803 }
805 /* sleep until we have space to write new frames */
806 if (pcm->running) {
807 /* enable waiting for avail_min threshold when less frames than we have to write
808 * are available. */
809 if (!pcm->wait_for_avail_min && (count > (unsigned int)avail))
810 pcm->wait_for_avail_min = 1;
812 if (pcm->wait_for_avail_min && (avail < pcm->config.avail_min)) {
813 int time = -1;
815 /* disable waiting for avail_min threshold to allow small amounts of data to be
816 * written without waiting as long as there is enough room in buffer. */
817 pcm->wait_for_avail_min = 0;
819 if (pcm->flags & PCM_NOIRQ)
820 time = (pcm->config.avail_min - avail) / pcm->noirq_frames_per_msec;
822 err = pcm_wait(pcm, time);
823 if (err < 0) {
824 pcm->running = 0;
825 oops(pcm, err, "wait error: hw 0x%x app 0x%x avail 0x%x\n",
826 (unsigned int)pcm->mmap_status->hw_ptr,
827 (unsigned int)pcm->mmap_control->appl_ptr,
828 avail);
829 pcm->mmap_control->appl_ptr = 0;
830 return err;
831 }
832 continue;
833 }
834 }
836 frames = count;
837 if (frames > avail)
838 frames = avail;
840 if (!frames)
841 break;
843 /* copy frames from buffer */
844 frames = pcm_mmap_write_areas(pcm, buffer, offset, frames);
845 if (frames < 0) {
846 fprintf(stderr, "write error: hw 0x%x app 0x%x avail 0x%x\n",
847 (unsigned int)pcm->mmap_status->hw_ptr,
848 (unsigned int)pcm->mmap_control->appl_ptr,
849 avail);
850 return frames;
851 }
853 offset += frames;
854 count -= frames;
855 }
857 _end:
858 return 0;
859 }