split out ALSA stream code
This commit is contained in:
Glenn Maynard
@@ -0,0 +1,174 @@
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#include "global.h"
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#include "RageLog.h"
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#include "ALSA9Helpers.h"
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#include "SDL_utils.h"
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/* int err; must be defined before using this macro */
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#define ALSA_ASSERT(x) \
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if (err < 0) { LOG->Trace("RageSound_ALSA9: ASSERT %s: %s", x, snd_strerror(err)); }
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Alsa9Buf::Alsa9Buf( hw hardware, int channels_, int samplerate_, int writeahead_ )
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{
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channels = channels_;
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samplerate = samplerate_;
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samplebits = 16;
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writeahead = writeahead_;
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// buffer_locked = false;
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last_cursor_pos = 0;
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//write_cursor = LastPosition = buffer_bytes_filled = 0;
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/* open the device */
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// if we instead use plughw: then our requested format WILL be provided
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int err;
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err = snd_pcm_open( &pcm, "hw:0,0", SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK );
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if (err < 0)
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RageException::ThrowNonfatal("snd_pcm_open: %s", snd_strerror(err));
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/* allocate the hardware parameters structure */
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snd_pcm_hw_params_t *hwparams;
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err = snd_pcm_hw_params_malloc(&hwparams);
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ALSA_ASSERT("snd_pcm_hw_params_malloc");
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/* not exactly sure what this does */
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err = snd_pcm_hw_params_any(pcm, hwparams);
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ALSA_ASSERT("snd_pcm_hw_params_any");
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/* set to mmap mode (with channels interleaved) */
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err = snd_pcm_hw_params_set_access(pcm, hwparams, SND_PCM_ACCESS_MMAP_INTERLEAVED);
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ALSA_ASSERT("snd_pcm_hw_params_set_access");
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/* set PCM format (signed 16bit, little endian) */
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err = snd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16_LE);
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ALSA_ASSERT("snd_pcm_hw_params_set_format");
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/* set number of channels */
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err = snd_pcm_hw_params_set_channels(pcm, hwparams, 2);
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ALSA_ASSERT("snd_pcm_hw_params_set_channels");
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unsigned int rate = samplerate;
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err = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, 0);
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// check if we got the rate we desire
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/* write the hardware parameters to the device */
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err = snd_pcm_hw_params(pcm, hwparams);
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ALSA_ASSERT("snd_pcm_hw_params");
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snd_pcm_hw_params_free(hwparams);
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/* prepare the device to reveice data */
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err = snd_pcm_prepare(pcm);
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ALSA_ASSERT("snd_pcm_prepare");
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//XXX should RageException::ThrowNonfatal if something went wrong
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/* prepare a snd_output_t for use with LOG->Trace */
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/* snd_output_t *errout = NULL;
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snd_output_buffer_open(&errout);
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snd_pcm_dump(pcm, errout);
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snd_output_flush(errout);
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char *errstring;
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snd_output_buffer_string(errout, &errstring);
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LOG->Trace("%s", errstring);
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snd_output_close( errout );
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*/
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total_frames = snd_pcm_avail_update(pcm);
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}
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Alsa9Buf::~Alsa9Buf()
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{
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snd_pcm_close(pcm);
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}
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int Alsa9Buf::GetNumFramesToFill()
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{
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snd_pcm_sframes_t avail_frames = snd_pcm_avail_update(pcm);
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if( avail_frames < 0 && Recover(avail_frames) )
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avail_frames = snd_pcm_avail_update(pcm);
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if( avail_frames < 0 )
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{
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LOG->Trace( "RageSoundDriver_ALSA9::GetData: snd_pcm_avail_update: %s", snd_strerror(avail_frames) );
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return 0;
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}
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const snd_pcm_sframes_t filled_frames = total_frames - avail_frames;
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const snd_pcm_sframes_t frames_to_fill = (writeahead - filled_frames) & ~3;
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ASSERT( frames_to_fill <= (int)writeahead );
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// LOG->Trace("%li avail, %li filled, %li to", avail_frames, filled_frames, frames_to_fill);
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return max( 0l, frames_to_fill );
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}
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void Alsa9Buf::Write( const Sint16 *buffer, int frames )
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{
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/* We should be able to write it all. If we don't, treat it as an error. */
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int wrote = snd_pcm_mmap_writei( pcm, (const char *) buffer, frames );
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if( wrote < 0 && Recover(wrote) )
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wrote = snd_pcm_mmap_writei( pcm, (const char *) buffer, frames );
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if( wrote < 0 )
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{
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LOG->Trace( "RageSoundDriver_ALSA9::GetData: snd_pcm_mmap_writei: %s", snd_strerror(wrote) );
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return;
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}
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last_cursor_pos += wrote;
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if( wrote < frames )
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LOG->Trace("Couldn't write whole buffer? (%i < %i)\n", wrote, frames );
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}
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/*
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* When the play buffer underruns, subsequent writes to the buffer
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* return -EPIPE. When this happens, call Recover() to restart playback.
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*/
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bool Alsa9Buf::Recover( int r )
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{
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if( r == -EPIPE )
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{
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LOG->Trace("RageSound_ALSA9::Recover (prepare)");
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int err = snd_pcm_prepare(pcm);
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ALSA_ASSERT("snd_pcm_prepare (Recover)");
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return true;
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}
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if( r == -ESTRPIPE )
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{
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LOG->Trace("RageSound_ALSA9::Recover (resume)");
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int err;
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while ((err = snd_pcm_resume(pcm)) == -EAGAIN)
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SDL_Delay(10);
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ALSA_ASSERT("snd_pcm_resume (Recover)");
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return true;
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}
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return false;
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}
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int Alsa9Buf::GetPosition() const
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{
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snd_pcm_status_t *status;
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snd_pcm_status_alloca(&status);
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int err = snd_pcm_status( pcm, status );
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ALSA_ASSERT("snd_pcm_status");
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snd_pcm_state_t state = snd_pcm_status_get_state( status );
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if ( state == SND_PCM_STATE_PREPARED )
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return 0;
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snd_pcm_hwsync( pcm );
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/* delay is returned in frames */
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snd_pcm_sframes_t delay = snd_pcm_status_get_delay(status);
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return last_cursor_pos - delay;
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}
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