Set a minimum sample count in ALSA target.

This should reduce unnecessary hardware interrupts. Apparently improves the
 ALSA target on some systems.

Fixes Bugzilla #1170.

Thanks to Paul Cercueil for the patch!

--HG--
branch : SDL-1.2
This commit is contained in:
Ryan C. Gordon
2011-08-21 11:42:47 -04:00
parent a5329adc36
commit 804f8e784c

View File

@@ -81,6 +81,7 @@ static int (*SDL_NAME(snd_pcm_hw_params_get_buffer_size))(const snd_pcm_hw_param
static int (*SDL_NAME(snd_pcm_hw_params))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params);
/*
*/
static int (*SDL_NAME(snd_pcm_sw_params_set_avail_min))(snd_pcm_t *pcm, snd_pcm_sw_params_t *swparams, snd_pcm_uframes_t val);
static int (*SDL_NAME(snd_pcm_sw_params_current))(snd_pcm_t *pcm, snd_pcm_sw_params_t *swparams);
static int (*SDL_NAME(snd_pcm_sw_params_set_start_threshold))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val);
static int (*SDL_NAME(snd_pcm_sw_params))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params);
@@ -117,6 +118,7 @@ static struct {
{ "snd_pcm_hw_params_set_buffer_size_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_buffer_size_near) },
{ "snd_pcm_hw_params_get_buffer_size", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_buffer_size) },
{ "snd_pcm_hw_params", (void**)(char*)&SDL_NAME(snd_pcm_hw_params) },
{ "snd_pcm_sw_params_set_avail_min", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_avail_min) },
{ "snd_pcm_sw_params_current", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_current) },
{ "snd_pcm_sw_params_set_start_threshold", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_start_threshold) },
{ "snd_pcm_sw_params", (void**)(char*)&SDL_NAME(snd_pcm_sw_params) },
@@ -578,6 +580,12 @@ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
ALSA_CloseAudio(this);
return(-1);
}
status = SDL_NAME(snd_pcm_sw_params_set_avail_min)(pcm_handle, swparams, spec->samples);
if ( status < 0 ) {
SDL_SetError("Couldn't set minimum available samples: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
return(-1);
}
status = SDL_NAME(snd_pcm_sw_params_set_start_threshold)(pcm_handle, swparams, 1);
if ( status < 0 ) {
SDL_SetError("Couldn't set start threshold: %s", SDL_NAME(snd_strerror)(status));