RetroArch/alsa.c
2010-08-17 23:06:44 +02:00

201 lines
5.2 KiB
C

/* SSNES - A Super Ninteno Entertainment System (SNES) Emulator frontend for libsnes.
* Copyright (C) 2010 - Hans-Kristian Arntzen
*
* Some code herein may be based on code found in BSNES.
*
* SSNES is free software: you can redistribute it and/or modify it under the terms
* of the GNU General Public License as published by the Free Software Found-
* ation, either version 3 of the License, or (at your option) any later version.
*
* SSNES is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with SSNES.
* If not, see <http://www.gnu.org/licenses/>.
*/
#include "driver.h"
#include <stdlib.h>
#include <alsa/asoundlib.h>
#define TRY_ALSA(x) if ( x < 0 ) { \
goto error; \
}
typedef struct alsa
{
snd_pcm_t *pcm;
bool nonblock;
} alsa_t;
static void* __alsa_init(const char* device, int rate, int latency)
{
alsa_t *alsa = calloc(1, sizeof(alsa_t));
if ( alsa == NULL )
return NULL;
snd_pcm_hw_params_t *params = NULL;
snd_pcm_sw_params_t *sw_params = NULL;
const char *alsa_dev = "default";
if ( device != NULL )
alsa_dev = device;
//fprintf(stderr, "Opening device: %s\n", alsa_dev);
TRY_ALSA(snd_pcm_open(&alsa->pcm, alsa_dev, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK));
unsigned int latency_usec = latency * 1000;
snd_pcm_format_t format = SND_PCM_FORMAT_S16_LE;
unsigned int channels = 2;
TRY_ALSA(snd_pcm_hw_params_malloc(&params));
TRY_ALSA(snd_pcm_hw_params_any(alsa->pcm, params));
TRY_ALSA(snd_pcm_hw_params_set_access(alsa->pcm, params, SND_PCM_ACCESS_RW_INTERLEAVED));
TRY_ALSA(snd_pcm_hw_params_set_format(alsa->pcm, params, format));
TRY_ALSA(snd_pcm_hw_params_set_channels(alsa->pcm, params, channels));
TRY_ALSA(snd_pcm_hw_params_set_rate(alsa->pcm, params, rate, 0));
// We test if we can run the latencies we are allowed, if not, fallback to *_near.
if ( snd_pcm_hw_params_set_buffer_time_max(alsa->pcm, params, &latency_usec, NULL) < 0)
{
latency_usec = latency * 1000;
TRY_ALSA(snd_pcm_hw_params_set_buffer_time_near(alsa->pcm, params, &latency_usec, NULL))
}
latency_usec = (latency < 32) ? 10000 : latency * 250;
if ( snd_pcm_hw_params_set_period_time_max(alsa->pcm, params, &latency_usec, NULL) )
{
latency_usec = (latency < 32) ? 10000 : latency * 250;
TRY_ALSA(snd_pcm_hw_params_set_period_time_near(alsa->pcm, params, &latency_usec, NULL));
}
TRY_ALSA(snd_pcm_hw_params(alsa->pcm, params));
snd_pcm_uframes_t buffer_size;
//snd_pcm_hw_params_get_period_size(params, &buffer_size, NULL);
//fprintf(stderr, "ALSA Period size: %d frames\n", (int)alsa_sizes);
snd_pcm_hw_params_get_buffer_size(params, &buffer_size);
//fprintf(stderr, "Buffer size: %d frames\n", (int)alsa_sizes);
if (snd_pcm_sw_params_malloc(&sw_params) < 0)
goto error;
TRY_ALSA(snd_pcm_sw_params_current(alsa->pcm, sw_params));
TRY_ALSA(snd_pcm_sw_params_set_start_threshold(alsa->pcm, sw_params, buffer_size/2));
TRY_ALSA(snd_pcm_sw_params(alsa->pcm, sw_params));
snd_pcm_sw_params_free(sw_params);
snd_pcm_hw_params_free(params);
return alsa;
error:
if ( params != NULL )
snd_pcm_hw_params_free(params);
if ( sw_params != NULL )
snd_pcm_sw_params_free(sw_params);
if ( alsa != NULL )
{
if ( alsa->pcm != NULL )
snd_pcm_close(alsa->pcm);
free(alsa);
}
return NULL;
}
static ssize_t __alsa_write(void* data, const void* buf, size_t size)
{
alsa_t *alsa = data;
snd_pcm_sframes_t frames;
snd_pcm_sframes_t written = 0;
int rc;
size /= 4; // Frames to write
while (written < size)
{
if (!alsa->nonblock)
{
rc = snd_pcm_wait(alsa->pcm, -1);
if (rc == -EPIPE || rc == -ESTRPIPE)
{
if (snd_pcm_recover(alsa->pcm, rc, 1) < 0)
return -1;
continue;
}
}
frames = snd_pcm_writei(alsa->pcm, (const uint32_t*)buf + written, size - written);
if ( frames == -EPIPE || frames == -EINTR || frames == -ESTRPIPE )
{
if ( snd_pcm_recover(alsa->pcm, frames, 1) < 0 )
return -1;
return 0;
}
else if ( frames == -EAGAIN && alsa->nonblock )
return 0;
else if ( frames < 0 )
return -1;
written += frames;
}
return snd_pcm_frames_to_bytes(alsa->pcm, size);
}
static bool __alsa_stop(void *data)
{
return true;
}
static void __alsa_set_nonblock_state(void *data, bool state)
{
alsa_t *alsa = data;
alsa->nonblock = state;
}
static bool __alsa_start(void *data)
{
return true;
}
static void __alsa_free(void *data)
{
alsa_t *alsa = data;
if ( alsa )
{
if ( alsa->pcm )
{
snd_pcm_drop(alsa->pcm);
snd_pcm_close(alsa->pcm);
}
free(alsa);
}
}
const audio_driver_t audio_alsa = {
.init = __alsa_init,
.write = __alsa_write,
.stop = __alsa_stop,
.start = __alsa_start,
.set_nonblock_state = __alsa_set_nonblock_state,
.free = __alsa_free
};