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qemu-e2k/audio/alsaaudio.c
Volker Rümelin 5a9d7ae251 alsaaudio: reduce playback latency 
Change the buffer_get_free pcm_ops function to report the free
ALSA playback buffer. The generic buffer becomes a temporary
buffer and is empty after a call to audio_run_out().

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220923183640.8314-4-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
2022-10-11 10:17:08 +02:00

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/*
* QEMU ALSA audio driver
*
* Copyright (c) 2005 Vassili Karpov (malc)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include <alsa/asoundlib.h>
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "audio.h"
#include "trace.h"
#pragma GCC diagnostic ignored "-Waddress"
#define AUDIO_CAP "alsa"
#include "audio_int.h"
#define DEBUG_ALSA 0
struct pollhlp {
snd_pcm_t *handle;
struct pollfd *pfds;
int count;
int mask;
AudioState *s;
};
typedef struct ALSAVoiceOut {
HWVoiceOut hw;
snd_pcm_t *handle;
struct pollhlp pollhlp;
Audiodev *dev;
} ALSAVoiceOut;
typedef struct ALSAVoiceIn {
HWVoiceIn hw;
snd_pcm_t *handle;
struct pollhlp pollhlp;
Audiodev *dev;
} ALSAVoiceIn;
struct alsa_params_req {
int freq;
snd_pcm_format_t fmt;
int nchannels;
};
struct alsa_params_obt {
int freq;
AudioFormat fmt;
int endianness;
int nchannels;
snd_pcm_uframes_t samples;
};
static void G_GNUC_PRINTF (2, 3) alsa_logerr (int err, const char *fmt, ...)
{
va_list ap;
va_start (ap, fmt);
AUD_vlog (AUDIO_CAP, fmt, ap);
va_end (ap);
AUD_log (AUDIO_CAP, "Reason: %s\n", snd_strerror (err));
}
static void G_GNUC_PRINTF (3, 4) alsa_logerr2 (
int err,
const char *typ,
const char *fmt,
...
)
{
va_list ap;
AUD_log (AUDIO_CAP, "Could not initialize %s\n", typ);
va_start (ap, fmt);
AUD_vlog (AUDIO_CAP, fmt, ap);
va_end (ap);
AUD_log (AUDIO_CAP, "Reason: %s\n", snd_strerror (err));
}
static void alsa_fini_poll (struct pollhlp *hlp)
{
int i;
struct pollfd *pfds = hlp->pfds;
if (pfds) {
for (i = 0; i < hlp->count; ++i) {
qemu_set_fd_handler (pfds[i].fd, NULL, NULL, NULL);
}
g_free (pfds);
}
hlp->pfds = NULL;
hlp->count = 0;
hlp->handle = NULL;
}
static void alsa_anal_close1 (snd_pcm_t **handlep)
{
int err = snd_pcm_close (*handlep);
if (err) {
alsa_logerr (err, "Failed to close PCM handle %p\n", *handlep);
}
*handlep = NULL;
}
static void alsa_anal_close (snd_pcm_t **handlep, struct pollhlp *hlp)
{
alsa_fini_poll (hlp);
alsa_anal_close1 (handlep);
}
static int alsa_recover (snd_pcm_t *handle)
{
int err = snd_pcm_prepare (handle);
if (err < 0) {
alsa_logerr (err, "Failed to prepare handle %p\n", handle);
return -1;
}
return 0;
}
static int alsa_resume (snd_pcm_t *handle)
{
int err = snd_pcm_resume (handle);
if (err < 0) {
alsa_logerr (err, "Failed to resume handle %p\n", handle);
return -1;
}
return 0;
}
static void alsa_poll_handler (void *opaque)
{
int err, count;
snd_pcm_state_t state;
struct pollhlp *hlp = opaque;
unsigned short revents;
count = poll (hlp->pfds, hlp->count, 0);
if (count < 0) {
dolog ("alsa_poll_handler: poll %s\n", strerror (errno));
return;
}
if (!count) {
return;
}
/* XXX: ALSA example uses initial count, not the one returned by
poll, correct? */
err = snd_pcm_poll_descriptors_revents (hlp->handle, hlp->pfds,
hlp->count, &revents);
if (err < 0) {
alsa_logerr (err, "snd_pcm_poll_descriptors_revents");
return;
}
if (!(revents & hlp->mask)) {
trace_alsa_revents(revents);
return;
}
state = snd_pcm_state (hlp->handle);
switch (state) {
case SND_PCM_STATE_SETUP:
alsa_recover (hlp->handle);
break;
case SND_PCM_STATE_XRUN:
alsa_recover (hlp->handle);
break;
case SND_PCM_STATE_SUSPENDED:
alsa_resume (hlp->handle);
break;
case SND_PCM_STATE_PREPARED:
audio_run(hlp->s, "alsa run (prepared)");
break;
case SND_PCM_STATE_RUNNING:
audio_run(hlp->s, "alsa run (running)");
break;
default:
dolog ("Unexpected state %d\n", state);
}
}
static int alsa_poll_helper (snd_pcm_t *handle, struct pollhlp *hlp, int mask)
{
int i, count, err;
struct pollfd *pfds;
count = snd_pcm_poll_descriptors_count (handle);
if (count <= 0) {
dolog ("Could not initialize poll mode\n"
"Invalid number of poll descriptors %d\n", count);
return -1;
}
pfds = audio_calloc ("alsa_poll_helper", count, sizeof (*pfds));
if (!pfds) {
dolog ("Could not initialize poll mode\n");
return -1;
}
err = snd_pcm_poll_descriptors (handle, pfds, count);
if (err < 0) {
alsa_logerr (err, "Could not initialize poll mode\n"
"Could not obtain poll descriptors\n");
g_free (pfds);
return -1;
}
for (i = 0; i < count; ++i) {
if (pfds[i].events & POLLIN) {
qemu_set_fd_handler (pfds[i].fd, alsa_poll_handler, NULL, hlp);
}
if (pfds[i].events & POLLOUT) {
trace_alsa_pollout(i, pfds[i].fd);
qemu_set_fd_handler (pfds[i].fd, NULL, alsa_poll_handler, hlp);
}
trace_alsa_set_handler(pfds[i].events, i, pfds[i].fd, err);
}
hlp->pfds = pfds;
hlp->count = count;
hlp->handle = handle;
hlp->mask = mask;
return 0;
}
static int alsa_poll_out (HWVoiceOut *hw)
{
ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
return alsa_poll_helper (alsa->handle, &alsa->pollhlp, POLLOUT);
}
static int alsa_poll_in (HWVoiceIn *hw)
{
ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
return alsa_poll_helper (alsa->handle, &alsa->pollhlp, POLLIN);
}
static snd_pcm_format_t aud_to_alsafmt (AudioFormat fmt, int endianness)
{
switch (fmt) {
case AUDIO_FORMAT_S8:
return SND_PCM_FORMAT_S8;
case AUDIO_FORMAT_U8:
return SND_PCM_FORMAT_U8;
case AUDIO_FORMAT_S16:
if (endianness) {
return SND_PCM_FORMAT_S16_BE;
} else {
return SND_PCM_FORMAT_S16_LE;
}
case AUDIO_FORMAT_U16:
if (endianness) {
return SND_PCM_FORMAT_U16_BE;
} else {
return SND_PCM_FORMAT_U16_LE;
}
case AUDIO_FORMAT_S32:
if (endianness) {
return SND_PCM_FORMAT_S32_BE;
} else {
return SND_PCM_FORMAT_S32_LE;
}
case AUDIO_FORMAT_U32:
if (endianness) {
return SND_PCM_FORMAT_U32_BE;
} else {
return SND_PCM_FORMAT_U32_LE;
}
case AUDIO_FORMAT_F32:
if (endianness) {
return SND_PCM_FORMAT_FLOAT_BE;
} else {
return SND_PCM_FORMAT_FLOAT_LE;
}
default:
dolog ("Internal logic error: Bad audio format %d\n", fmt);
#ifdef DEBUG_AUDIO
abort ();
#endif
return SND_PCM_FORMAT_U8;
}
}
static int alsa_to_audfmt (snd_pcm_format_t alsafmt, AudioFormat *fmt,
int *endianness)
{
switch (alsafmt) {
case SND_PCM_FORMAT_S8:
*endianness = 0;
*fmt = AUDIO_FORMAT_S8;
break;
case SND_PCM_FORMAT_U8:
*endianness = 0;
*fmt = AUDIO_FORMAT_U8;
break;
case SND_PCM_FORMAT_S16_LE:
*endianness = 0;
*fmt = AUDIO_FORMAT_S16;
break;
case SND_PCM_FORMAT_U16_LE:
*endianness = 0;
*fmt = AUDIO_FORMAT_U16;
break;
case SND_PCM_FORMAT_S16_BE:
*endianness = 1;
*fmt = AUDIO_FORMAT_S16;
break;
case SND_PCM_FORMAT_U16_BE:
*endianness = 1;
*fmt = AUDIO_FORMAT_U16;
break;
case SND_PCM_FORMAT_S32_LE:
*endianness = 0;
*fmt = AUDIO_FORMAT_S32;
break;
case SND_PCM_FORMAT_U32_LE:
*endianness = 0;
*fmt = AUDIO_FORMAT_U32;
break;
case SND_PCM_FORMAT_S32_BE:
*endianness = 1;
*fmt = AUDIO_FORMAT_S32;
break;
case SND_PCM_FORMAT_U32_BE:
*endianness = 1;
*fmt = AUDIO_FORMAT_U32;
break;
case SND_PCM_FORMAT_FLOAT_LE:
*endianness = 0;
*fmt = AUDIO_FORMAT_F32;
break;
case SND_PCM_FORMAT_FLOAT_BE:
*endianness = 1;
*fmt = AUDIO_FORMAT_F32;
break;
default:
dolog ("Unrecognized audio format %d\n", alsafmt);
return -1;
}
return 0;
}
static void alsa_dump_info (struct alsa_params_req *req,
struct alsa_params_obt *obt,
snd_pcm_format_t obtfmt,
AudiodevAlsaPerDirectionOptions *apdo)
{
dolog("parameter | requested value | obtained value\n");
dolog("format | %10d | %10d\n", req->fmt, obtfmt);
dolog("channels | %10d | %10d\n",
req->nchannels, obt->nchannels);
dolog("frequency | %10d | %10d\n", req->freq, obt->freq);
dolog("============================================\n");
dolog("requested: buffer len %" PRId32 " period len %" PRId32 "\n",
apdo->buffer_length, apdo->period_length);
dolog("obtained: samples %ld\n", obt->samples);
}
static void alsa_set_threshold (snd_pcm_t *handle, snd_pcm_uframes_t threshold)
{
int err;
snd_pcm_sw_params_t *sw_params;
snd_pcm_sw_params_alloca (&sw_params);
err = snd_pcm_sw_params_current (handle, sw_params);
if (err < 0) {
dolog ("Could not fully initialize DAC\n");
alsa_logerr (err, "Failed to get current software parameters\n");
return;
}
err = snd_pcm_sw_params_set_start_threshold (handle, sw_params, threshold);
if (err < 0) {
dolog ("Could not fully initialize DAC\n");
alsa_logerr (err, "Failed to set software threshold to %ld\n",
threshold);
return;
}
err = snd_pcm_sw_params (handle, sw_params);
if (err < 0) {
dolog ("Could not fully initialize DAC\n");
alsa_logerr (err, "Failed to set software parameters\n");
return;
}
}
static int alsa_open(bool in, struct alsa_params_req *req,
struct alsa_params_obt *obt, snd_pcm_t **handlep,
Audiodev *dev)
{
AudiodevAlsaOptions *aopts = &dev->u.alsa;
AudiodevAlsaPerDirectionOptions *apdo = in ? aopts->in : aopts->out;
snd_pcm_t *handle;
snd_pcm_hw_params_t *hw_params;
int err;
unsigned int freq, nchannels;
const char *pcm_name = apdo->has_dev ? apdo->dev : "default";
snd_pcm_uframes_t obt_buffer_size;
const char *typ = in ? "ADC" : "DAC";
snd_pcm_format_t obtfmt;
freq = req->freq;
nchannels = req->nchannels;
snd_pcm_hw_params_alloca (&hw_params);
err = snd_pcm_open (
&handle,
pcm_name,
in ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK,
SND_PCM_NONBLOCK
);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to open `%s':\n", pcm_name);
return -1;
}
err = snd_pcm_hw_params_any (handle, hw_params);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to initialize hardware parameters\n");
goto err;
}
err = snd_pcm_hw_params_set_access (
handle,
hw_params,
SND_PCM_ACCESS_RW_INTERLEAVED
);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to set access type\n");
goto err;
}
err = snd_pcm_hw_params_set_format (handle, hw_params, req->fmt);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to set format %d\n", req->fmt);
}
err = snd_pcm_hw_params_set_rate_near (handle, hw_params, &freq, 0);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to set frequency %d\n", req->freq);
goto err;
}
err = snd_pcm_hw_params_set_channels_near (
handle,
hw_params,
&nchannels
);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to set number of channels %d\n",
req->nchannels);
goto err;
}
if (apdo->buffer_length) {
int dir = 0;
unsigned int btime = apdo->buffer_length;
err = snd_pcm_hw_params_set_buffer_time_near(
handle, hw_params, &btime, &dir);
if (err < 0) {
alsa_logerr2(err, typ, "Failed to set buffer time to %" PRId32 "\n",
apdo->buffer_length);
goto err;
}
if (apdo->has_buffer_length && btime != apdo->buffer_length) {
dolog("Requested buffer time %" PRId32
" was rejected, using %u\n", apdo->buffer_length, btime);
}
}
if (apdo->period_length) {
int dir = 0;
unsigned int ptime = apdo->period_length;
err = snd_pcm_hw_params_set_period_time_near(handle, hw_params, &ptime,
&dir);
if (err < 0) {
alsa_logerr2(err, typ, "Failed to set period time to %" PRId32 "\n",
apdo->period_length);
goto err;
}
if (apdo->has_period_length && ptime != apdo->period_length) {
dolog("Requested period time %" PRId32 " was rejected, using %d\n",
apdo->period_length, ptime);
}
}
err = snd_pcm_hw_params (handle, hw_params);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to apply audio parameters\n");
goto err;
}
err = snd_pcm_hw_params_get_buffer_size (hw_params, &obt_buffer_size);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to get buffer size\n");
goto err;
}
err = snd_pcm_hw_params_get_format (hw_params, &obtfmt);
if (err < 0) {
alsa_logerr2 (err, typ, "Failed to get format\n");
goto err;
}
if (alsa_to_audfmt (obtfmt, &obt->fmt, &obt->endianness)) {
dolog ("Invalid format was returned %d\n", obtfmt);
goto err;
}
err = snd_pcm_prepare (handle);
if (err < 0) {
alsa_logerr2 (err, typ, "Could not prepare handle %p\n", handle);
goto err;
}
if (!in && aopts->has_threshold && aopts->threshold) {
struct audsettings as = { .freq = freq };
alsa_set_threshold(
handle,
audio_buffer_frames(qapi_AudiodevAlsaPerDirectionOptions_base(apdo),
&as, aopts->threshold));
}
obt->nchannels = nchannels;
obt->freq = freq;
obt->samples = obt_buffer_size;
*handlep = handle;
if (DEBUG_ALSA || obtfmt != req->fmt ||
obt->nchannels != req->nchannels || obt->freq != req->freq) {
dolog ("Audio parameters for %s\n", typ);
alsa_dump_info(req, obt, obtfmt, apdo);
}
return 0;
err:
alsa_anal_close1 (&handle);
return -1;
}
static size_t alsa_buffer_get_free(HWVoiceOut *hw)
{
ALSAVoiceOut *alsa = (ALSAVoiceOut *)hw;
snd_pcm_sframes_t avail;
size_t alsa_free, generic_free, generic_in_use;
avail = snd_pcm_avail_update(alsa->handle);
if (avail < 0) {
if (avail == -EPIPE) {
if (!alsa_recover(alsa->handle)) {
avail = snd_pcm_avail_update(alsa->handle);
}
}
if (avail < 0) {
alsa_logerr(avail,
"Could not obtain number of available frames\n");
avail = 0;
}
}
alsa_free = avail * hw->info.bytes_per_frame;
generic_free = audio_generic_buffer_get_free(hw);
generic_in_use = hw->samples * hw->info.bytes_per_frame - generic_free;
if (generic_in_use) {
/*
* This code can only be reached in the unlikely case that
* snd_pcm_avail_update() returned a larger number of frames
* than snd_pcm_writei() could write. Make sure that all
* remaining bytes in the generic buffer can be written.
*/
alsa_free = alsa_free > generic_in_use ? alsa_free - generic_in_use : 0;
}
return alsa_free;
}
static size_t alsa_write(HWVoiceOut *hw, void *buf, size_t len)
{
ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
size_t pos = 0;
size_t len_frames = len / hw->info.bytes_per_frame;
while (len_frames) {
char *src = advance(buf, pos);
snd_pcm_sframes_t written;
written = snd_pcm_writei(alsa->handle, src, len_frames);
if (written <= 0) {
switch (written) {
case 0:
trace_alsa_wrote_zero(len_frames);
return pos;
case -EPIPE:
if (alsa_recover(alsa->handle)) {
alsa_logerr(written, "Failed to write %zu frames\n",
len_frames);
return pos;
}
trace_alsa_xrun_out();
continue;
case -ESTRPIPE:
/*
* stream is suspended and waiting for an application
* recovery
*/
if (alsa_resume(alsa->handle)) {
alsa_logerr(written, "Failed to write %zu frames\n",
len_frames);
return pos;
}
trace_alsa_resume_out();
continue;
case -EAGAIN:
return pos;
default:
alsa_logerr(written, "Failed to write %zu frames from %p\n",
len, src);
return pos;
}
}
pos += written * hw->info.bytes_per_frame;
if (written < len_frames) {
break;
}
len_frames -= written;
}
return pos;
}
static void alsa_fini_out (HWVoiceOut *hw)
{
ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
ldebug ("alsa_fini\n");
alsa_anal_close (&alsa->handle, &alsa->pollhlp);
}
static int alsa_init_out(HWVoiceOut *hw, struct audsettings *as,
void *drv_opaque)
{
ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
struct alsa_params_req req;
struct alsa_params_obt obt;
snd_pcm_t *handle;
struct audsettings obt_as;
Audiodev *dev = drv_opaque;
req.fmt = aud_to_alsafmt (as->fmt, as->endianness);
req.freq = as->freq;
req.nchannels = as->nchannels;
if (alsa_open(0, &req, &obt, &handle, dev)) {
return -1;
}
obt_as.freq = obt.freq;
obt_as.nchannels = obt.nchannels;
obt_as.fmt = obt.fmt;
obt_as.endianness = obt.endianness;
audio_pcm_init_info (&hw->info, &obt_as);
hw->samples = obt.samples;
alsa->pollhlp.s = hw->s;
alsa->handle = handle;
alsa->dev = dev;
return 0;
}
#define VOICE_CTL_PAUSE 0
#define VOICE_CTL_PREPARE 1
#define VOICE_CTL_START 2
static int alsa_voice_ctl (snd_pcm_t *handle, const char *typ, int ctl)
{
int err;
if (ctl == VOICE_CTL_PAUSE) {
err = snd_pcm_drop (handle);
if (err < 0) {
alsa_logerr (err, "Could not stop %s\n", typ);
return -1;
}
} else {
err = snd_pcm_prepare (handle);
if (err < 0) {
alsa_logerr (err, "Could not prepare handle for %s\n", typ);
return -1;
}
if (ctl == VOICE_CTL_START) {
err = snd_pcm_start(handle);
if (err < 0) {
alsa_logerr (err, "Could not start handle for %s\n", typ);
return -1;
}
}
}
return 0;
}
static void alsa_enable_out(HWVoiceOut *hw, bool enable)
{
ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
AudiodevAlsaPerDirectionOptions *apdo = alsa->dev->u.alsa.out;
if (enable) {
bool poll_mode = apdo->try_poll;
ldebug("enabling voice\n");
if (poll_mode && alsa_poll_out(hw)) {
poll_mode = 0;
}
hw->poll_mode = poll_mode;
alsa_voice_ctl(alsa->handle, "playback", VOICE_CTL_PREPARE);
} else {
ldebug("disabling voice\n");
if (hw->poll_mode) {
hw->poll_mode = 0;
alsa_fini_poll(&alsa->pollhlp);
}
alsa_voice_ctl(alsa->handle, "playback", VOICE_CTL_PAUSE);
}
}
static int alsa_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
{
ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
struct alsa_params_req req;
struct alsa_params_obt obt;
snd_pcm_t *handle;
struct audsettings obt_as;
Audiodev *dev = drv_opaque;
req.fmt = aud_to_alsafmt (as->fmt, as->endianness);
req.freq = as->freq;
req.nchannels = as->nchannels;
if (alsa_open(1, &req, &obt, &handle, dev)) {
return -1;
}
obt_as.freq = obt.freq;
obt_as.nchannels = obt.nchannels;
obt_as.fmt = obt.fmt;
obt_as.endianness = obt.endianness;
audio_pcm_init_info (&hw->info, &obt_as);
hw->samples = obt.samples;
alsa->pollhlp.s = hw->s;
alsa->handle = handle;
alsa->dev = dev;
return 0;
}
static void alsa_fini_in (HWVoiceIn *hw)
{
ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
alsa_anal_close (&alsa->handle, &alsa->pollhlp);
}
static size_t alsa_read(HWVoiceIn *hw, void *buf, size_t len)
{
ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
size_t pos = 0;
while (len) {
void *dst = advance(buf, pos);
snd_pcm_sframes_t nread;
nread = snd_pcm_readi(
alsa->handle, dst, len / hw->info.bytes_per_frame);
if (nread <= 0) {
switch (nread) {
case 0:
trace_alsa_read_zero(len);
return pos;
case -EPIPE:
if (alsa_recover(alsa->handle)) {
alsa_logerr(nread, "Failed to read %zu frames\n", len);
return pos;
}
trace_alsa_xrun_in();
continue;
case -EAGAIN:
return pos;
default:
alsa_logerr(nread, "Failed to read %zu frames to %p\n",
len, dst);
return pos;
}
}
pos += nread * hw->info.bytes_per_frame;
len -= nread * hw->info.bytes_per_frame;
}
return pos;
}
static void alsa_enable_in(HWVoiceIn *hw, bool enable)
{
ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
AudiodevAlsaPerDirectionOptions *apdo = alsa->dev->u.alsa.in;
if (enable) {
bool poll_mode = apdo->try_poll;
ldebug("enabling voice\n");
if (poll_mode && alsa_poll_in(hw)) {
poll_mode = 0;
}
hw->poll_mode = poll_mode;
alsa_voice_ctl(alsa->handle, "capture", VOICE_CTL_START);
} else {
ldebug ("disabling voice\n");
if (hw->poll_mode) {
hw->poll_mode = 0;
alsa_fini_poll(&alsa->pollhlp);
}
alsa_voice_ctl(alsa->handle, "capture", VOICE_CTL_PAUSE);
}
}
static void alsa_init_per_direction(AudiodevAlsaPerDirectionOptions *apdo)
{
if (!apdo->has_try_poll) {
apdo->try_poll = true;
apdo->has_try_poll = true;
}
}
static void *alsa_audio_init(Audiodev *dev)
{
AudiodevAlsaOptions *aopts;
assert(dev->driver == AUDIODEV_DRIVER_ALSA);
aopts = &dev->u.alsa;
alsa_init_per_direction(aopts->in);
alsa_init_per_direction(aopts->out);
/*
* need to define them, as otherwise alsa produces no sound
* doesn't set has_* so alsa_open can identify it wasn't set by the user
*/
if (!dev->u.alsa.out->has_period_length) {
/* 1024 frames assuming 44100Hz */
dev->u.alsa.out->period_length = 1024 * 1000000 / 44100;
}
if (!dev->u.alsa.out->has_buffer_length) {
/* 4096 frames assuming 44100Hz */
dev->u.alsa.out->buffer_length = 4096ll * 1000000 / 44100;
}
/*
* OptsVisitor sets unspecified optional fields to zero, but do not depend
* on it...
*/
if (!dev->u.alsa.in->has_period_length) {
dev->u.alsa.in->period_length = 0;
}
if (!dev->u.alsa.in->has_buffer_length) {
dev->u.alsa.in->buffer_length = 0;
}
return dev;
}
static void alsa_audio_fini (void *opaque)
{
}
static struct audio_pcm_ops alsa_pcm_ops = {
.init_out = alsa_init_out,
.fini_out = alsa_fini_out,
.write = alsa_write,
.buffer_get_free = alsa_buffer_get_free,
.run_buffer_out = audio_generic_run_buffer_out,
.enable_out = alsa_enable_out,
.init_in = alsa_init_in,
.fini_in = alsa_fini_in,
.read = alsa_read,
.run_buffer_in = audio_generic_run_buffer_in,
.enable_in = alsa_enable_in,
};
static struct audio_driver alsa_audio_driver = {
.name = "alsa",
.descr = "ALSA http://www.alsa-project.org",
.init = alsa_audio_init,
.fini = alsa_audio_fini,
.pcm_ops = &alsa_pcm_ops,
.can_be_default = 1,
.max_voices_out = INT_MAX,
.max_voices_in = INT_MAX,
.voice_size_out = sizeof (ALSAVoiceOut),
.voice_size_in = sizeof (ALSAVoiceIn)
};
static void register_audio_alsa(void)
{
audio_driver_register(&alsa_audio_driver);
}
type_init(register_audio_alsa);
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