blob: 04d4396a1acfb5eda9bd32473a0db26ea3d1ae14 [file] [log] [blame]
/* pcm.c
**
** Copyright 2011, The Android Open Source Project
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
** * Neither the name of The Android Open Source Project nor the names of
** its contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY The Android Open Source Project ``AS IS'' AND
** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
** ARE DISCLAIMED. IN NO EVENT SHALL The Android Open Source Project BE LIABLE
** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
** SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
** DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <poll.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <limits.h>
#include <linux/ioctl.h>
#define __force
#define __bitwise
#define __user
#include <sound/asound.h>
#include <tinyalsa/asoundlib.h>
#define PARAM_MAX SNDRV_PCM_HW_PARAM_LAST_INTERVAL
#define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2)
static inline int param_is_mask(int p)
{
return (p >= SNDRV_PCM_HW_PARAM_FIRST_MASK) &&
(p <= SNDRV_PCM_HW_PARAM_LAST_MASK);
}
static inline int param_is_interval(int p)
{
return (p >= SNDRV_PCM_HW_PARAM_FIRST_INTERVAL) &&
(p <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL);
}
static inline struct snd_interval *param_to_interval(struct snd_pcm_hw_params *p, int n)
{
return &(p->intervals[n - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL]);
}
static inline struct snd_mask *param_to_mask(struct snd_pcm_hw_params *p, int n)
{
return &(p->masks[n - SNDRV_PCM_HW_PARAM_FIRST_MASK]);
}
static void param_set_mask(struct snd_pcm_hw_params *p, int n, unsigned int bit)
{
if (bit >= SNDRV_MASK_MAX)
return;
if (param_is_mask(n)) {
struct snd_mask *m = param_to_mask(p, n);
m->bits[0] = 0;
m->bits[1] = 0;
m->bits[bit >> 5] |= (1 << (bit & 31));
}
}
static void param_set_min(struct snd_pcm_hw_params *p, int n, unsigned int val)
{
if (param_is_interval(n)) {
struct snd_interval *i = param_to_interval(p, n);
i->min = val;
}
}
static void param_set_max(struct snd_pcm_hw_params *p, int n, unsigned int val)
{
if (param_is_interval(n)) {
struct snd_interval *i = param_to_interval(p, n);
i->max = val;
}
}
static void param_set_int(struct snd_pcm_hw_params *p, int n, unsigned int val)
{
if (param_is_interval(n)) {
struct snd_interval *i = param_to_interval(p, n);
i->min = val;
i->max = val;
i->integer = 1;
}
}
static unsigned int param_get_int(struct snd_pcm_hw_params *p, int n)
{
if (param_is_interval(n)) {
struct snd_interval *i = param_to_interval(p, n);
if (i->integer)
return i->max;
}
return 0;
}
static void param_init(struct snd_pcm_hw_params *p)
{
int n;
memset(p, 0, sizeof(*p));
for (n = SNDRV_PCM_HW_PARAM_FIRST_MASK;
n <= SNDRV_PCM_HW_PARAM_LAST_MASK; n++) {
struct snd_mask *m = param_to_mask(p, n);
m->bits[0] = ~0;
m->bits[1] = ~0;
}
for (n = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL;
n <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; n++) {
struct snd_interval *i = param_to_interval(p, n);
i->min = 0;
i->max = ~0;
}
}
#define PCM_ERROR_MAX 128
struct pcm {
int fd;
unsigned int flags;
int running:1;
int underruns;
unsigned int buffer_size;
unsigned int boundary;
char error[PCM_ERROR_MAX];
struct pcm_config config;
struct snd_pcm_mmap_status *mmap_status;
struct snd_pcm_mmap_control *mmap_control;
struct snd_pcm_sync_ptr *sync_ptr;
void *mmap_buffer;
unsigned int noirq_frames_per_msec;
int wait_for_avail_min;
};
unsigned int pcm_get_buffer_size(struct pcm *pcm)
{
return pcm->buffer_size;
}
const char* pcm_get_error(struct pcm *pcm)
{
return pcm->error;
}
static int oops(struct pcm *pcm, int e, const char *fmt, ...)
{
va_list ap;
int sz;
va_start(ap, fmt);
vsnprintf(pcm->error, PCM_ERROR_MAX, fmt, ap);
va_end(ap);
sz = strlen(pcm->error);
if (errno)
snprintf(pcm->error + sz, PCM_ERROR_MAX - sz,
": %s", strerror(e));
return -1;
}
static unsigned int pcm_format_to_alsa(enum pcm_format format)
{
switch (format) {
case PCM_FORMAT_S32_LE:
return SNDRV_PCM_FORMAT_S32_LE;
default:
case PCM_FORMAT_S16_LE:
return SNDRV_PCM_FORMAT_S16_LE;
};
}
static unsigned int pcm_format_to_bits(enum pcm_format format)
{
switch (format) {
case PCM_FORMAT_S32_LE:
return 32;
default:
case PCM_FORMAT_S16_LE:
return 16;
};
}
unsigned int pcm_bytes_to_frames(struct pcm *pcm, unsigned int bytes)
{
return bytes / (pcm->config.channels *
(pcm_format_to_bits(pcm->config.format) >> 3));
}
unsigned int pcm_frames_to_bytes(struct pcm *pcm, unsigned int frames)
{
return frames * pcm->config.channels *
(pcm_format_to_bits(pcm->config.format) >> 3);
}
static int pcm_sync_ptr(struct pcm *pcm, int flags) {
if (pcm->sync_ptr) {
pcm->sync_ptr->flags = flags;
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SYNC_PTR, pcm->sync_ptr) < 0)
return -1;
}
return 0;
}
static int pcm_hw_mmap_status(struct pcm *pcm) {
if (pcm->sync_ptr)
return 0;
int page_size = sysconf(_SC_PAGE_SIZE);
pcm->mmap_status = mmap(NULL, page_size, PROT_READ, MAP_FILE | MAP_SHARED,
pcm->fd, SNDRV_PCM_MMAP_OFFSET_STATUS);
if (pcm->mmap_status == MAP_FAILED)
pcm->mmap_status = NULL;
if (!pcm->mmap_status)
goto mmap_error;
pcm->mmap_control = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
MAP_FILE | MAP_SHARED, pcm->fd, SNDRV_PCM_MMAP_OFFSET_CONTROL);
if (pcm->mmap_control == MAP_FAILED)
pcm->mmap_control = NULL;
if (!pcm->mmap_control) {
munmap(pcm->mmap_status, page_size);
pcm->mmap_status = NULL;
goto mmap_error;
}
if (pcm->flags & PCM_MMAP)
pcm->mmap_control->avail_min = pcm->config.avail_min;
else
pcm->mmap_control->avail_min = 1;
return 0;
mmap_error:
pcm->sync_ptr = calloc(1, sizeof(*pcm->sync_ptr));
if (!pcm->sync_ptr)
return -ENOMEM;
pcm->mmap_status = &pcm->sync_ptr->s.status;
pcm->mmap_control = &pcm->sync_ptr->c.control;
if (pcm->flags & PCM_MMAP)
pcm->mmap_control->avail_min = pcm->config.avail_min;
else
pcm->mmap_control->avail_min = 1;
pcm_sync_ptr(pcm, 0);
return 0;
}
static void pcm_hw_munmap_status(struct pcm *pcm) {
if (pcm->sync_ptr) {
free(pcm->sync_ptr);
pcm->sync_ptr = NULL;
} else {
int page_size = sysconf(_SC_PAGE_SIZE);
if (pcm->mmap_status)
munmap(pcm->mmap_status, page_size);
if (pcm->mmap_control)
munmap(pcm->mmap_control, page_size);
}
pcm->mmap_status = NULL;
pcm->mmap_control = NULL;
}
static int pcm_areas_copy(struct pcm *pcm, unsigned int pcm_offset,
const char *src, unsigned int src_offset,
unsigned int frames)
{
int size_bytes = pcm_frames_to_bytes(pcm, frames);
int pcm_offset_bytes = pcm_frames_to_bytes(pcm, pcm_offset);
int src_offset_bytes = pcm_frames_to_bytes(pcm, src_offset);
/* interleaved only atm */
memcpy((char*)pcm->mmap_buffer + pcm_offset_bytes,
src + src_offset_bytes, size_bytes);
return 0;
}
static int pcm_mmap_write_areas(struct pcm *pcm, char *src,
unsigned int offset, unsigned int size)
{
void *pcm_areas;
int commit;
unsigned int pcm_offset, frames, count = 0;
while (size > 0) {
frames = size;
pcm_mmap_begin(pcm, &pcm_areas, &pcm_offset, &frames);
pcm_areas_copy(pcm, pcm_offset, src, offset, frames);
commit = pcm_mmap_commit(pcm, pcm_offset, frames);
if (commit < 0) {
oops(pcm, commit, "failed to commit %d frames\n", frames);
return commit;
}
offset += commit;
count += commit;
size -= commit;
}
return count;
}
int pcm_get_htimestamp(struct pcm *pcm, unsigned int *avail,
struct timespec *tstamp)
{
int frames;
int rc;
snd_pcm_uframes_t hw_ptr;
if (!pcm_is_ready(pcm))
return -1;
rc = pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_APPL|SNDRV_PCM_SYNC_PTR_HWSYNC);
if (rc < 0)
return -1;
if ((pcm->mmap_status->state != PCM_STATE_RUNNING) &&
(pcm->mmap_status->state != PCM_STATE_DRAINING))
return -1;
*tstamp = pcm->mmap_status->tstamp;
if (tstamp->tv_sec == 0 && tstamp->tv_nsec == 0)
return -1;
hw_ptr = pcm->mmap_status->hw_ptr;
if (pcm->flags & PCM_IN)
frames = hw_ptr - pcm->mmap_control->appl_ptr;
else
frames = hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr;
if (frames < 0)
frames += pcm->boundary;
else if (frames > (int)pcm->boundary)
frames -= pcm->boundary;
*avail = (unsigned int)frames;
return 0;
}
int pcm_write(struct pcm *pcm, void *data, unsigned int count)
{
struct snd_xferi x;
if (pcm->flags & PCM_IN)
return -EINVAL;
x.buf = data;
x.frames = count / (pcm->config.channels *
pcm_format_to_bits(pcm->config.format) / 8);
for (;;) {
if (!pcm->running) {
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE))
return oops(pcm, errno, "cannot prepare channel");
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &x))
return oops(pcm, errno, "cannot write initial data");
pcm->running = 1;
return 0;
}
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_WRITEI_FRAMES, &x)) {
pcm->running = 0;
if (errno == EPIPE) {
/* we failed to make our window -- try to restart */
pcm->underruns++;
continue;
}
return oops(pcm, errno, "cannot write stream data");
}
return 0;
}
}
int pcm_read(struct pcm *pcm, void *data, unsigned int count)
{
struct snd_xferi x;
if (!(pcm->flags & PCM_IN))
return -EINVAL;
x.buf = data;
x.frames = count / (pcm->config.channels *
pcm_format_to_bits(pcm->config.format) / 8);
for (;;) {
if (!pcm->running) {
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE))
return oops(pcm, errno, "cannot prepare channel");
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_START))
return oops(pcm, errno, "cannot start channel");
pcm->running = 1;
}
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_READI_FRAMES, &x)) {
pcm->running = 0;
if (errno == EPIPE) {
/* we failed to make our window -- try to restart */
pcm->underruns++;
continue;
}
return oops(pcm, errno, "cannot read stream data");
}
return 0;
}
}
static struct pcm bad_pcm = {
.fd = -1,
};
int pcm_close(struct pcm *pcm)
{
if (pcm == &bad_pcm)
return 0;
pcm_hw_munmap_status(pcm);
if (pcm->flags & PCM_MMAP) {
pcm_stop(pcm);
munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
}
if (pcm->fd >= 0)
close(pcm->fd);
pcm->running = 0;
pcm->buffer_size = 0;
pcm->fd = -1;
free(pcm);
return 0;
}
struct pcm *pcm_open(unsigned int card, unsigned int device,
unsigned int flags, struct pcm_config *config)
{
struct pcm *pcm;
struct snd_pcm_info info;
struct snd_pcm_hw_params params;
struct snd_pcm_sw_params sparams;
char fn[256];
int rc;
pcm = calloc(1, sizeof(struct pcm));
if (!pcm || !config)
return &bad_pcm; /* TODO: could support default config here */
pcm->config = *config;
snprintf(fn, sizeof(fn), "/dev/snd/pcmC%uD%u%c", card, device,
flags & PCM_IN ? 'c' : 'p');
pcm->flags = flags;
pcm->fd = open(fn, O_RDWR);
if (pcm->fd < 0) {
oops(pcm, errno, "cannot open device '%s'", fn);
return pcm;
}
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_INFO, &info)) {
oops(pcm, errno, "cannot get info");
goto fail_close;
}
param_init(&params);
param_set_mask(&params, SNDRV_PCM_HW_PARAM_FORMAT,
pcm_format_to_alsa(config->format));
param_set_mask(&params, SNDRV_PCM_HW_PARAM_SUBFORMAT,
SNDRV_PCM_SUBFORMAT_STD);
param_set_min(&params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, config->period_size);
param_set_int(&params, SNDRV_PCM_HW_PARAM_SAMPLE_BITS,
pcm_format_to_bits(config->format));
param_set_int(&params, SNDRV_PCM_HW_PARAM_FRAME_BITS,
pcm_format_to_bits(config->format) * config->channels);
param_set_int(&params, SNDRV_PCM_HW_PARAM_CHANNELS,
config->channels);
param_set_int(&params, SNDRV_PCM_HW_PARAM_PERIODS, config->period_count);
param_set_int(&params, SNDRV_PCM_HW_PARAM_RATE, config->rate);
if (flags & PCM_NOIRQ) {
if (!(flags & PCM_MMAP)) {
oops(pcm, -EINVAL, "noirq only currently supported with mmap().");
goto fail;
}
params.flags |= SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP;
pcm->noirq_frames_per_msec = config->rate / 1000;
}
if (flags & PCM_MMAP)
param_set_mask(&params, SNDRV_PCM_HW_PARAM_ACCESS,
SNDRV_PCM_ACCESS_MMAP_INTERLEAVED);
else
param_set_mask(&params, SNDRV_PCM_HW_PARAM_ACCESS,
SNDRV_PCM_ACCESS_RW_INTERLEAVED);
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_HW_PARAMS, &params)) {
oops(pcm, errno, "cannot set hw params");
goto fail_close;
}
/* get our refined hw_params */
config->period_size = param_get_int(&params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE);
config->period_count = param_get_int(&params, SNDRV_PCM_HW_PARAM_PERIODS);
pcm->buffer_size = config->period_count * config->period_size;
if (flags & PCM_MMAP) {
pcm->mmap_buffer = mmap(NULL, pcm_frames_to_bytes(pcm, pcm->buffer_size),
PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, pcm->fd, 0);
if (pcm->mmap_buffer == MAP_FAILED) {
oops(pcm, -errno, "failed to mmap buffer %d bytes\n",
pcm_frames_to_bytes(pcm, pcm->buffer_size));
goto fail_close;
}
}
memset(&sparams, 0, sizeof(sparams));
sparams.tstamp_mode = SNDRV_PCM_TSTAMP_ENABLE;
sparams.period_step = 1;
if (!config->start_threshold)
pcm->config.start_threshold = sparams.start_threshold =
config->period_count * config->period_size / 2;
else
sparams.start_threshold = config->start_threshold;
/* pick a high stop threshold - todo: does this need further tuning */
if (!config->stop_threshold)
pcm->config.stop_threshold = sparams.stop_threshold =
config->period_count * config->period_size;
else
sparams.stop_threshold = config->stop_threshold;
if (!pcm->config.avail_min) {
if (pcm->flags & PCM_MMAP)
pcm->config.avail_min = sparams.avail_min = pcm->config.period_size;
else
pcm->config.avail_min = sparams.avail_min = 1;
} else
sparams.avail_min = config->avail_min;
sparams.xfer_align = config->period_size / 2; /* needed for old kernels */
sparams.silence_size = 0;
sparams.silence_threshold = config->silence_threshold;
pcm->boundary = sparams.boundary = pcm->buffer_size;
while (pcm->boundary * 2 <= LONG_MAX - pcm->buffer_size)
pcm->boundary *= 2;
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_SW_PARAMS, &sparams)) {
oops(pcm, errno, "cannot set sw params");
goto fail;
}
rc = pcm_hw_mmap_status(pcm);
if (rc < 0) {
oops(pcm, rc, "mmap status failed");
goto fail;
}
pcm->underruns = 0;
return pcm;
fail:
if (flags & PCM_MMAP)
munmap(pcm->mmap_buffer, pcm_frames_to_bytes(pcm, pcm->buffer_size));
fail_close:
close(pcm->fd);
pcm->fd = -1;
return pcm;
}
int pcm_is_ready(struct pcm *pcm)
{
return pcm->fd >= 0;
}
int pcm_start(struct pcm *pcm)
{
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_PREPARE) < 0)
return oops(pcm, errno, "cannot prepare channel");
if (pcm->flags & PCM_MMAP)
pcm_sync_ptr(pcm, 0);
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_START) < 0)
return oops(pcm, errno, "cannot start channel");
pcm->running = 1;
return 0;
}
int pcm_stop(struct pcm *pcm)
{
if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_DROP) < 0)
return oops(pcm, errno, "cannot stop channel");
pcm->running = 0;
return 0;
}
static inline int pcm_mmap_playback_avail(struct pcm *pcm)
{
int avail;
avail = pcm->mmap_status->hw_ptr + pcm->buffer_size - pcm->mmap_control->appl_ptr;
if (avail < 0)
avail += pcm->boundary;
else if (avail > (int)pcm->boundary)
avail -= pcm->boundary;
return avail;
}
static inline int pcm_mmap_capture_avail(struct pcm *pcm)
{
int avail = pcm->mmap_status->hw_ptr - pcm->mmap_control->appl_ptr;
if (avail < 0)
avail += pcm->boundary;
return avail;
}
static inline int pcm_mmap_avail(struct pcm *pcm)
{
pcm_sync_ptr(pcm, SNDRV_PCM_SYNC_PTR_HWSYNC);
if (pcm->flags & PCM_IN)
return pcm_mmap_capture_avail(pcm);
else
return pcm_mmap_playback_avail(pcm);
}
static void pcm_mmap_appl_forward(struct pcm *pcm, int frames)
{
unsigned int appl_ptr = pcm->mmap_control->appl_ptr;
appl_ptr += frames;
/* check for boundary wrap */
if (appl_ptr > pcm->boundary)
appl_ptr -= pcm->boundary;
pcm->mmap_control->appl_ptr = appl_ptr;
}
int pcm_mmap_begin(struct pcm *pcm, void **areas, unsigned int *offset,
unsigned int *frames)
{
unsigned int continuous, copy_frames, avail;
/* return the mmap buffer */
*areas = pcm->mmap_buffer;
/* and the application offset in frames */
*offset = pcm->mmap_control->appl_ptr % pcm->buffer_size;
avail = pcm_mmap_avail(pcm);
if (avail > pcm->buffer_size)
avail = pcm->buffer_size;
continuous = pcm->buffer_size - *offset;
/* we can only copy frames if the are availabale and continuos */
copy_frames = *frames;
if (copy_frames > avail)
copy_frames = avail;
if (copy_frames > continuous)
copy_frames = continuous;
*frames = copy_frames;
return 0;
}
int pcm_mmap_commit(struct pcm *pcm, unsigned int offset, unsigned int frames)
{
/* update the application pointer in userspace and kernel */
pcm_mmap_appl_forward(pcm, frames);
pcm_sync_ptr(pcm, 0);
return frames;
}
int pcm_avail_update(struct pcm *pcm)
{
pcm_sync_ptr(pcm, 0);
return pcm_mmap_avail(pcm);
}
int pcm_state(struct pcm *pcm)
{
int err = pcm_sync_ptr(pcm, 0);
if (err < 0)
return err;
return pcm->mmap_status->state;
}
int pcm_set_avail_min(struct pcm *pcm, int avail_min)
{
if ((~pcm->flags) & (PCM_MMAP | PCM_NOIRQ))
return -ENOSYS;
pcm->config.avail_min = avail_min;
return 0;
}
int pcm_wait(struct pcm *pcm, int timeout)
{
struct pollfd pfd;
unsigned short revents = 0;
int err;
pfd.fd = pcm->fd;
pfd.events = POLLOUT | POLLERR | POLLNVAL;
do {
/* let's wait for avail or timeout */
err = poll(&pfd, 1, timeout);
if (err < 0)
return -errno;
/* timeout ? */
if (err == 0)
return 0;
/* have we been interrupted ? */
if (errno == -EINTR)
continue;
/* check for any errors */
if (pfd.revents & (POLLERR | POLLNVAL)) {
switch (pcm_state(pcm)) {
case PCM_STATE_XRUN:
return -EPIPE;
case PCM_STATE_SUSPENDED:
return -ESTRPIPE;
case PCM_STATE_DISCONNECTED:
return -ENODEV;
default:
return -EIO;
}
}
/* poll again if fd not ready for IO */
} while (!(pfd.revents & (POLLIN | POLLOUT)));
return 1;
}
int pcm_mmap_write(struct pcm *pcm, void *buffer, unsigned int bytes)
{
int err = 0, frames, avail;
unsigned int offset = 0, count;
if (bytes == 0)
return 0;
count = pcm_bytes_to_frames(pcm, bytes);
while (count > 0) {
/* get the available space for writing new frames */
avail = pcm_avail_update(pcm);
if (avail < 0) {
fprintf(stderr, "cannot determine available mmap frames");
return err;
}
/* start the audio if we reach the threshold */
if (!pcm->running &&
(pcm->buffer_size - avail) >= pcm->config.start_threshold) {
if (pcm_start(pcm) < 0) {
fprintf(stderr, "start error: hw 0x%x app 0x%x avail 0x%x\n",
(unsigned int)pcm->mmap_status->hw_ptr,
(unsigned int)pcm->mmap_control->appl_ptr,
avail);
return -errno;
}
pcm->wait_for_avail_min = 0;
}
/* sleep until we have space to write new frames */
if (pcm->running) {
/* enable waiting for avail_min threshold when less frames than we have to write
* are available. */
if (!pcm->wait_for_avail_min && (count > (unsigned int)avail))
pcm->wait_for_avail_min = 1;
if (pcm->wait_for_avail_min && (avail < pcm->config.avail_min)) {
int time = -1;
/* disable waiting for avail_min threshold to allow small amounts of data to be
* written without waiting as long as there is enough room in buffer. */
pcm->wait_for_avail_min = 0;
if (pcm->flags & PCM_NOIRQ)
time = (pcm->config.avail_min - avail) / pcm->noirq_frames_per_msec;
err = pcm_wait(pcm, time);
if (err < 0) {
pcm->running = 0;
oops(pcm, err, "wait error: hw 0x%x app 0x%x avail 0x%x\n",
(unsigned int)pcm->mmap_status->hw_ptr,
(unsigned int)pcm->mmap_control->appl_ptr,
avail);
pcm->mmap_control->appl_ptr = 0;
return err;
}
continue;
}
}
frames = count;
if (frames > avail)
frames = avail;
if (!frames)
break;
/* copy frames from buffer */
frames = pcm_mmap_write_areas(pcm, buffer, offset, frames);
if (frames < 0) {
fprintf(stderr, "write error: hw 0x%x app 0x%x avail 0x%x\n",
(unsigned int)pcm->mmap_status->hw_ptr,
(unsigned int)pcm->mmap_control->appl_ptr,
avail);
return frames;
}
offset += frames;
count -= frames;
}
_end:
return 0;
}