nkeynes@66: /**
nkeynes@561:  * $Id$
nkeynes@66:  * 
nkeynes@66:  * Audio mixer core. Combines all the active streams into a single sound
nkeynes@66:  * buffer for output. 
nkeynes@66:  *
nkeynes@66:  * Copyright (c) 2005 Nathan Keynes.
nkeynes@66:  *
nkeynes@66:  * This program is free software; you can redistribute it and/or modify
nkeynes@66:  * it under the terms of the GNU General Public License as published by
nkeynes@66:  * the Free Software Foundation; either version 2 of the License, or
nkeynes@66:  * (at your option) any later version.
nkeynes@66:  *
nkeynes@66:  * This program is distributed in the hope that it will be useful,
nkeynes@66:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
nkeynes@66:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nkeynes@66:  * GNU General Public License for more details.
nkeynes@66:  */
nkeynes@66: 
nkeynes@66: #include "aica/aica.h"
nkeynes@66: #include "aica/audio.h"
nkeynes@700: #include <glib/gmem.h>
nkeynes@66: #include "dream.h"
nkeynes@66: #include <assert.h>
nkeynes@66: #include <string.h>
nkeynes@66: 
nkeynes@1024: #define MAX_AUDIO_DRIVERS 16
nkeynes@697: extern struct audio_driver audio_null_driver;
nkeynes@697: extern struct audio_driver audio_osx_driver;
nkeynes@697: extern struct audio_driver audio_pulse_driver;
nkeynes@697: extern struct audio_driver audio_esd_driver;
nkeynes@697: extern struct audio_driver audio_alsa_driver;
nkeynes@989: extern struct audio_driver audio_sdl_driver;
nkeynes@697: 
nkeynes@1024: static int audio_driver_count = 0;
nkeynes@1024: static audio_driver_t audio_driver_list[MAX_AUDIO_DRIVERS] = {};
nkeynes@531: 
nkeynes@66: #define NUM_BUFFERS 3
nkeynes@700: #define MS_PER_BUFFER 100
nkeynes@66: 
nkeynes@66: #define BUFFER_EMPTY   0
nkeynes@66: #define BUFFER_WRITING 1
nkeynes@66: #define BUFFER_FULL    2
nkeynes@66: 
nkeynes@66: struct audio_state {
nkeynes@66:     audio_buffer_t output_buffers[NUM_BUFFERS];
nkeynes@66:     int write_buffer;
nkeynes@66:     int read_buffer;
nkeynes@66:     uint32_t output_format;
nkeynes@66:     uint32_t output_rate;
nkeynes@66:     uint32_t output_sample_size;
nkeynes@465:     struct audio_channel channels[AUDIO_CHANNEL_COUNT];
nkeynes@66: } audio;
nkeynes@66: 
nkeynes@66: audio_driver_t audio_driver = NULL;
nkeynes@66: 
nkeynes@66: #define NEXT_BUFFER() ((audio.write_buffer == NUM_BUFFERS-1) ? 0 : audio.write_buffer+1)
nkeynes@66: 
nkeynes@66: /**
nkeynes@465:  * Preserve audio channel state only - don't bother saving the buffers
nkeynes@465:  */
nkeynes@465: void audio_save_state( FILE *f )
nkeynes@465: {
nkeynes@465:     fwrite( &audio.channels[0], sizeof(struct audio_channel), AUDIO_CHANNEL_COUNT, f );
nkeynes@465: }
nkeynes@465: 
nkeynes@465: int audio_load_state( FILE *f )
nkeynes@465: {
nkeynes@465:     int read = fread( &audio.channels[0], sizeof(struct audio_channel), AUDIO_CHANNEL_COUNT, f );
nkeynes@465:     return (read == AUDIO_CHANNEL_COUNT ? 0 : -1 );
nkeynes@465: }
nkeynes@465: 
nkeynes@1024: static int audio_driver_priority_compare(const void *a, const void *b)
nkeynes@1024: {
nkeynes@1024:     audio_driver_t ada = *(audio_driver_t *)a;
nkeynes@1024:     audio_driver_t adb = *(audio_driver_t *)b;
nkeynes@1024:     return ada->priority - adb->priority;
nkeynes@1024: }
nkeynes@1024: 
nkeynes@1024: static int audio_driver_name_compare(const void *a, const void *b)
nkeynes@1024: {
nkeynes@1024:     audio_driver_t ada = *(audio_driver_t *)a;
nkeynes@1024:     audio_driver_t adb = *(audio_driver_t *)b;
nkeynes@1024:     return strcasecmp( ada->name, adb->name );
nkeynes@1024: }
nkeynes@1024: 
nkeynes@1024: 
nkeynes@1024: 
nkeynes@1024: gboolean audio_register_driver( audio_driver_t driver )
nkeynes@1024: {
nkeynes@1024:     if( audio_driver_count >= MAX_AUDIO_DRIVERS ) {
nkeynes@1024:         return FALSE;
nkeynes@1024:     }
nkeynes@1024:     audio_driver_list[audio_driver_count++] = driver;
nkeynes@1024:     qsort( audio_driver_list, audio_driver_count, sizeof( audio_driver_t ), audio_driver_priority_compare );
nkeynes@1024:     return TRUE;
nkeynes@1024: }
nkeynes@1024: 
nkeynes@531: audio_driver_t get_audio_driver_by_name( const char *name )
nkeynes@531: {
nkeynes@531:     int i;
nkeynes@531:     if( name == NULL ) {
nkeynes@697:         return audio_driver_list[0];
nkeynes@531:     }
nkeynes@1024:     for( i=0; i < audio_driver_count; i++ ) {
nkeynes@697:         if( strcasecmp( audio_driver_list[i]->name, name ) == 0 ) {
nkeynes@697:             return audio_driver_list[i];
nkeynes@697:         }
nkeynes@531:     }
nkeynes@531: 
nkeynes@531:     return NULL;
nkeynes@531: }
nkeynes@531: 
nkeynes@700: void print_audio_drivers( FILE * out )
nkeynes@700: {
nkeynes@700:     int i;
nkeynes@1024:     audio_driver_t temp_list[MAX_AUDIO_DRIVERS];
nkeynes@1024:     memcpy( temp_list, audio_driver_list, audio_driver_count*sizeof(audio_driver_t) );
nkeynes@1024:     qsort( temp_list, audio_driver_count, sizeof(audio_driver_t), audio_driver_name_compare );
nkeynes@700:     fprintf( out, "Available audio drivers:\n" );
nkeynes@1024:     for( i=0; i < audio_driver_count; i++ ) {
nkeynes@1024:         fprintf( out, "  %-8s %s\n", temp_list[i]->name,
nkeynes@1024:                 gettext(temp_list[i]->description) );
nkeynes@700:     }
nkeynes@700: }
nkeynes@700: 
nkeynes@697: audio_driver_t audio_init_driver( const char *preferred_driver )
nkeynes@697: {
nkeynes@697:     audio_driver_t audio_driver = get_audio_driver_by_name(preferred_driver);
nkeynes@697:     if( audio_driver == NULL ) {
nkeynes@697:         ERROR( "Audio driver '%s' not found, aborting.", preferred_driver );
nkeynes@697:         exit(2);
nkeynes@697:     } else if( audio_set_driver( audio_driver ) == FALSE ) {
nkeynes@779:         int i;
nkeynes@1024:         for( i=0; i < audio_driver_count; i++ ) {
nkeynes@779:             if( audio_driver_list[i] != audio_driver &&
nkeynes@779:                 audio_set_driver( audio_driver_list[i] ) ) {
nkeynes@779:                 ERROR( "Failed to initialize audio driver %s, falling back to %s", 
nkeynes@779:                        audio_driver->name, audio_driver_list[i]->name );
nkeynes@779:                 return audio_driver_list[i];
nkeynes@779:             }
nkeynes@779:         }
nkeynes@779:         ERROR( "Unable to intialize any audio driver, aborting." );
nkeynes@779:         exit(2);
nkeynes@759:     }
nkeynes@759:     return audio_driver;
nkeynes@697: }
nkeynes@697: 
nkeynes@1024: void audio_start_driver(void)
nkeynes@1024: {
nkeynes@1024:     if( audio_driver != NULL && audio_driver->start != NULL ) {
nkeynes@1024:         audio_driver->start();
nkeynes@1024:     }
nkeynes@1024: }
nkeynes@1024: 
nkeynes@1024: void audio_stop_driver(void)
nkeynes@1024: {
nkeynes@1024:     if( audio_driver != NULL && audio_driver->stop != NULL ) {
nkeynes@1024:         audio_driver->stop();
nkeynes@1024:     }
nkeynes@1024: }
nkeynes@1024: 
nkeynes@465: /**
nkeynes@66:  * Set the output driver, sample rate and format. Also initializes the 
nkeynes@66:  * output buffers, flushing any current data and reallocating as 
nkeynes@66:  * necessary.
nkeynes@66:  */
nkeynes@697: gboolean audio_set_driver( audio_driver_t driver )
nkeynes@66: {
nkeynes@66:     uint32_t bytes_per_sample = 1;
nkeynes@66:     uint32_t samples_per_buffer;
nkeynes@66:     int i;
nkeynes@66: 
nkeynes@111:     if( audio_driver == NULL || driver != NULL ) {
nkeynes@697:         if( driver == NULL  )
nkeynes@697:             driver = &audio_null_driver;
nkeynes@697:         if( driver != audio_driver ) {	
nkeynes@697:             if( !driver->init() )
nkeynes@697:                 return FALSE;
nkeynes@697:             audio_driver = driver;
nkeynes@697:         }
nkeynes@111:     }
nkeynes@111: 
nkeynes@697:     switch( driver->sample_format & AUDIO_FMT_SAMPLE_MASK ) {
nkeynes@697:     case AUDIO_FMT_8BIT:
nkeynes@697:         bytes_per_sample = 1;
nkeynes@697:         break;
nkeynes@697:     case AUDIO_FMT_16BIT:
nkeynes@697:         bytes_per_sample = 2;
nkeynes@697:         break;
nkeynes@697:     case AUDIO_FMT_FLOAT:
nkeynes@697:         bytes_per_sample = 4;
nkeynes@697:         break;
nkeynes@697:     }
nkeynes@697: 
nkeynes@697:     if( driver->sample_format & AUDIO_FMT_STEREO )
nkeynes@697:         bytes_per_sample <<= 1;
nkeynes@697:     if( driver->sample_rate == audio.output_rate &&
nkeynes@697:             bytes_per_sample == audio.output_sample_size )
nkeynes@697:         return TRUE;
nkeynes@697:     samples_per_buffer = (driver->sample_rate * MS_PER_BUFFER / 1000);
nkeynes@66:     for( i=0; i<NUM_BUFFERS; i++ ) {
nkeynes@697:         if( audio.output_buffers[i] != NULL )
nkeynes@697:             free(audio.output_buffers[i]);
nkeynes@697:         audio.output_buffers[i] = g_malloc0( sizeof(struct audio_buffer) + samples_per_buffer * bytes_per_sample );
nkeynes@697:         audio.output_buffers[i]->length = samples_per_buffer * bytes_per_sample;
nkeynes@697:         audio.output_buffers[i]->posn = 0;
nkeynes@697:         audio.output_buffers[i]->status = BUFFER_EMPTY;
nkeynes@66:     }
nkeynes@697:     audio.output_format = driver->sample_format;
nkeynes@697:     audio.output_rate = driver->sample_rate;
nkeynes@66:     audio.output_sample_size = bytes_per_sample;
nkeynes@66:     audio.write_buffer = 0;
nkeynes@66:     audio.read_buffer = 0;
nkeynes@66: 
nkeynes@111:     return TRUE;
nkeynes@66: }
nkeynes@66: 
nkeynes@66: /**
nkeynes@66:  * Mark the current write buffer as full and prepare the next buffer for
nkeynes@66:  * writing. Returns the next buffer to write to.
nkeynes@66:  * If all buffers are full, returns NULL.
nkeynes@66:  */
nkeynes@66: audio_buffer_t audio_next_write_buffer( )
nkeynes@66: {
nkeynes@66:     audio_buffer_t result = NULL;
nkeynes@66:     audio_buffer_t current = audio.output_buffers[audio.write_buffer];
nkeynes@66:     current->status = BUFFER_FULL;
nkeynes@66:     if( audio.read_buffer == audio.write_buffer &&
nkeynes@697:             audio_driver->process_buffer( current ) ) {
nkeynes@697:         audio_next_read_buffer();
nkeynes@66:     }
nkeynes@697:     int next_buffer = NEXT_BUFFER();
nkeynes@697:     result = audio.output_buffers[next_buffer];
nkeynes@66:     if( result->status == BUFFER_FULL )
nkeynes@697:         return NULL;
nkeynes@66:     else {
nkeynes@697:         audio.write_buffer = next_buffer;
nkeynes@697:         result->status = BUFFER_WRITING;
nkeynes@697:         return result;
nkeynes@66:     }
nkeynes@66: }
nkeynes@66: 
nkeynes@66: /**
nkeynes@66:  * Mark the current read buffer as empty and return the next buffer for
nkeynes@66:  * reading. If there is no next buffer yet, returns NULL.
nkeynes@66:  */
nkeynes@66: audio_buffer_t audio_next_read_buffer( )
nkeynes@66: {
nkeynes@66:     audio_buffer_t current = audio.output_buffers[audio.read_buffer];
nkeynes@697:     if( current->status == BUFFER_FULL ) {
nkeynes@697:         // Current read buffer has data, which we've just emptied
nkeynes@697:         current->status = BUFFER_EMPTY;
nkeynes@697:         current->posn = 0;
nkeynes@697:         audio.read_buffer++;
nkeynes@697:         if( audio.read_buffer == NUM_BUFFERS )
nkeynes@697:             audio.read_buffer = 0;
nkeynes@697: 
nkeynes@697:         current = audio.output_buffers[audio.read_buffer];
nkeynes@697:         if( current->status == BUFFER_FULL ) {
nkeynes@697:             current->posn = 0;
nkeynes@697:             return current;
nkeynes@697:         }
nkeynes@697:         else return NULL;
nkeynes@697:     } else {
nkeynes@697:         return NULL;
nkeynes@697:     }
nkeynes@697: 
nkeynes@66: }
nkeynes@66: 
nkeynes@66: /*************************** ADPCM ***********************************/
nkeynes@66: 
nkeynes@66: /**
nkeynes@66:  * The following section borrows heavily from ffmpeg, which is
nkeynes@66:  * copyright (c) 2001-2003 by the fine folks at the ffmpeg project,
nkeynes@66:  * distributed under the GPL version 2 or later.
nkeynes@66:  */
nkeynes@66: 
nkeynes@66: #define CLAMP_TO_SHORT(value) \
nkeynes@736:     if (value > 32767) \
nkeynes@66:     value = 32767; \
nkeynes@736:     else if (value < -32768) \
nkeynes@66:     value = -32768; \
nkeynes@66: 
nkeynes@66: static const int yamaha_indexscale[] = {
nkeynes@736:         230, 230, 230, 230, 307, 409, 512, 614,
nkeynes@736:         230, 230, 230, 230, 307, 409, 512, 614
nkeynes@66: };
nkeynes@66: 
nkeynes@66: static const int yamaha_difflookup[] = {
nkeynes@736:         1, 3, 5, 7, 9, 11, 13, 15,
nkeynes@736:         -1, -3, -5, -7, -9, -11, -13, -15
nkeynes@66: };
nkeynes@66: 
nkeynes@66: static inline short adpcm_yamaha_decode_nibble( audio_channel_t c, 
nkeynes@736:                                                 unsigned char nibble )
nkeynes@66: {
nkeynes@66:     if( c->adpcm_step == 0 ) {
nkeynes@66:         c->adpcm_predict = 0;
nkeynes@66:         c->adpcm_step = 127;
nkeynes@66:     }
nkeynes@66: 
nkeynes@66:     c->adpcm_predict += (c->adpcm_step * yamaha_difflookup[nibble]) >> 3;
nkeynes@66:     CLAMP_TO_SHORT(c->adpcm_predict);
nkeynes@66:     c->adpcm_step = (c->adpcm_step * yamaha_indexscale[nibble]) >> 8;
nkeynes@66:     c->adpcm_step = CLAMP(c->adpcm_step, 127, 24567);
nkeynes@66:     return c->adpcm_predict;
nkeynes@66: }
nkeynes@66: 
nkeynes@66: /*************************** Sample mixer *****************************/
nkeynes@66: 
nkeynes@66: /**
nkeynes@66:  * Mix a single output sample.
nkeynes@66:  */
nkeynes@73: void audio_mix_samples( int num_samples )
nkeynes@66: {
nkeynes@66:     int i, j;
nkeynes@73:     int32_t result_buf[num_samples][2];
nkeynes@73: 
nkeynes@73:     memset( &result_buf, 0, sizeof(result_buf) );
nkeynes@66: 
nkeynes@465:     for( i=0; i < AUDIO_CHANNEL_COUNT; i++ ) {
nkeynes@697:         audio_channel_t channel = &audio.channels[i];
nkeynes@697:         if( channel->active ) {
nkeynes@697:             int32_t sample;
nkeynes@697:             int vol_left = (channel->vol * (32 - channel->pan)) >> 5;
nkeynes@697:             int vol_right = (channel->vol * (channel->pan + 1)) >> 5;
nkeynes@697:             switch( channel->sample_format ) {
nkeynes@697:             case AUDIO_FMT_16BIT:
nkeynes@697:                 for( j=0; j<num_samples; j++ ) {
nkeynes@1089:                     sample = *(int16_t *)(aica_main_ram + ((channel->start + channel->posn*2)&AUDIO_MEM_MASK));
nkeynes@697:                     result_buf[j][0] += sample * vol_left;
nkeynes@697:                     result_buf[j][1] += sample * vol_right;
nkeynes@697: 
nkeynes@697:                     channel->posn_left += channel->sample_rate;
nkeynes@697:                     while( channel->posn_left > audio.output_rate ) {
nkeynes@697:                         channel->posn_left -= audio.output_rate;
nkeynes@697:                         channel->posn++;
nkeynes@697: 
nkeynes@697:                         if( channel->posn == channel->end ) {
nkeynes@697:                             if( channel->loop ) {
nkeynes@697:                                 channel->posn = channel->loop_start;
nkeynes@697:                                 channel->loop = LOOP_LOOPED;
nkeynes@697:                             } else {
nkeynes@697:                                 audio_stop_channel(i);
nkeynes@697:                                 j = num_samples;
nkeynes@697:                                 break;
nkeynes@697:                             }
nkeynes@697:                         }
nkeynes@697:                     }
nkeynes@697:                 }
nkeynes@697:                 break;
nkeynes@697:             case AUDIO_FMT_8BIT:
nkeynes@697:                 for( j=0; j<num_samples; j++ ) {
nkeynes@1089:                     sample = (*(int8_t *)(aica_main_ram + ((channel->start + channel->posn)&AUDIO_MEM_MASK))) << 8;
nkeynes@697:                     result_buf[j][0] += sample * vol_left;
nkeynes@697:                     result_buf[j][1] += sample * vol_right;
nkeynes@697: 
nkeynes@697:                     channel->posn_left += channel->sample_rate;
nkeynes@697:                     while( channel->posn_left > audio.output_rate ) {
nkeynes@697:                         channel->posn_left -= audio.output_rate;
nkeynes@697:                         channel->posn++;
nkeynes@697: 
nkeynes@697:                         if( channel->posn == channel->end ) {
nkeynes@697:                             if( channel->loop ) {
nkeynes@697:                                 channel->posn = channel->loop_start;
nkeynes@697:                                 channel->loop = LOOP_LOOPED;
nkeynes@697:                             } else {
nkeynes@697:                                 audio_stop_channel(i);
nkeynes@697:                                 j = num_samples;
nkeynes@697:                                 break;
nkeynes@697:                             }
nkeynes@697:                         }
nkeynes@697:                     }
nkeynes@697:                 }
nkeynes@697:                 break;
nkeynes@697:             case AUDIO_FMT_ADPCM:
nkeynes@697:                 for( j=0; j<num_samples; j++ ) {
nkeynes@697:                     sample = (int16_t)channel->adpcm_predict;
nkeynes@697:                     result_buf[j][0] += sample * vol_left;
nkeynes@697:                     result_buf[j][1] += sample * vol_right;
nkeynes@697:                     channel->posn_left += channel->sample_rate;
nkeynes@697:                     while( channel->posn_left > audio.output_rate ) {
nkeynes@697:                         channel->posn_left -= audio.output_rate;
nkeynes@697:                         channel->posn++;
nkeynes@697:                         if( channel->posn == channel->end ) {
nkeynes@697:                             if( channel->loop ) {
nkeynes@697:                                 channel->posn = channel->loop_start;
nkeynes@697:                                 channel->loop = LOOP_LOOPED;
nkeynes@697:                                 channel->adpcm_predict = 0;
nkeynes@697:                                 channel->adpcm_step = 0;
nkeynes@697:                             } else {
nkeynes@697:                                 audio_stop_channel(i);
nkeynes@697:                                 j = num_samples;
nkeynes@697:                                 break;
nkeynes@697:                             }
nkeynes@697:                         }
nkeynes@1089:                         uint8_t data = *(uint8_t *)(aica_main_ram + ((channel->start + (channel->posn>>1))&AUDIO_MEM_MASK));
nkeynes@697:                         if( channel->posn&1 ) {
nkeynes@697:                             adpcm_yamaha_decode_nibble( channel, (data >> 4) & 0x0F );
nkeynes@697:                         } else {
nkeynes@697:                             adpcm_yamaha_decode_nibble( channel, data & 0x0F );
nkeynes@697:                         }
nkeynes@697:                     }
nkeynes@697:                 }
nkeynes@697:                 break;
nkeynes@697:             default:
nkeynes@697:                 break;
nkeynes@697:             }
nkeynes@697:         }
nkeynes@66:     }
nkeynes@736: 
nkeynes@66:     /* Down-render to the final output format */
nkeynes@697:     audio_buffer_t buf = audio.output_buffers[audio.write_buffer];
nkeynes@697:     if( buf->status == BUFFER_FULL ) {
nkeynes@697:         buf = audio_next_write_buffer();
nkeynes@697:         if( buf == NULL ) { // no available space
nkeynes@697:             return;
nkeynes@697:         }
nkeynes@697:     }
nkeynes@736: 
nkeynes@697:     switch( audio.output_format & AUDIO_FMT_SAMPLE_MASK ) {
nkeynes@697:     case AUDIO_FMT_FLOAT: {
nkeynes@697:         float scale = 1.0/SHRT_MAX;
nkeynes@697:         float *data = (float *)&buf->data[buf->posn];
nkeynes@697:         for( j=0; j<num_samples; j++ ) {
nkeynes@697:             *data++ = scale * (result_buf[j][0] >> 6);
nkeynes@697:             *data++ = scale * (result_buf[j][1] >> 6);
nkeynes@697:             buf->posn += 8;
nkeynes@697:             if( buf->posn == buf->length ) {
nkeynes@697:                 buf = audio_next_write_buffer();
nkeynes@697:                 if( buf == NULL ) {
nkeynes@697:                     break;
nkeynes@697:                 }
nkeynes@697:                 data = (float *)&buf->data[0];
nkeynes@697:             }
nkeynes@697:         }
nkeynes@697:         break;
nkeynes@697:     }
nkeynes@697:     case AUDIO_FMT_16BIT: {
nkeynes@697:         int16_t *data = (int16_t *)&buf->data[buf->posn];
nkeynes@697:         for( j=0; j < num_samples; j++ ) {
nkeynes@697:             *data++ = (int16_t)(result_buf[j][0] >> 6);
nkeynes@697:             *data++ = (int16_t)(result_buf[j][1] >> 6);	
nkeynes@697:             buf->posn += 4;
nkeynes@697:             if( buf->posn == buf->length ) {
nkeynes@697:                 buf = audio_next_write_buffer();
nkeynes@697:                 if( buf == NULL ) {
nkeynes@697:                     // All buffers are full
nkeynes@697:                     break;
nkeynes@697:                 }
nkeynes@697:                 data = (int16_t *)&buf->data[0];
nkeynes@697:             }
nkeynes@697:         }
nkeynes@697:         break;
nkeynes@697:     }
nkeynes@697:     case AUDIO_FMT_8BIT: {
nkeynes@700:         int8_t *data = (int8_t *)&buf->data[buf->posn];
nkeynes@697:         for( j=0; j < num_samples; j++ ) {
nkeynes@697:             *data++ = (int8_t)(result_buf[j][0] >> 16);
nkeynes@697:             *data++ = (int8_t)(result_buf[j][1] >> 16);	
nkeynes@697:             buf->posn += 2;
nkeynes@697:             if( buf->posn == buf->length ) {
nkeynes@697:                 buf = audio_next_write_buffer();
nkeynes@697:                 if( buf == NULL ) {
nkeynes@697:                     // All buffers are full
nkeynes@697:                     break;
nkeynes@697:                 }
nkeynes@697:                 buf = audio.output_buffers[audio.write_buffer];
nkeynes@700:                 data = (int8_t *)&buf->data[0];
nkeynes@697:             }
nkeynes@697:         }
nkeynes@697:         break;
nkeynes@697:     }
nkeynes@66:     }
nkeynes@66: }
nkeynes@66: 
nkeynes@66: /********************** Internal AICA calls ***************************/
nkeynes@66: 
nkeynes@66: audio_channel_t audio_get_channel( int channel ) 
nkeynes@66: {
nkeynes@66:     return &audio.channels[channel];
nkeynes@66: }
nkeynes@66: 
nkeynes@434: void audio_start_stop_channel( int channel, gboolean start )
nkeynes@434: {
nkeynes@434:     if( audio.channels[channel].active ) {
nkeynes@736:         if( !start ) {
nkeynes@736:             audio_stop_channel(channel);
nkeynes@736:         }
nkeynes@434:     } else if( start ) {
nkeynes@736:         audio_start_channel(channel);
nkeynes@434:     }
nkeynes@434: }
nkeynes@434: 
nkeynes@66: void audio_stop_channel( int channel ) 
nkeynes@66: {
nkeynes@66:     audio.channels[channel].active = FALSE;
nkeynes@66: }
nkeynes@66: 
nkeynes@66: 
nkeynes@66: void audio_start_channel( int channel )
nkeynes@66: {
nkeynes@66:     audio.channels[channel].posn = 0;
nkeynes@66:     audio.channels[channel].posn_left = 0;
nkeynes@66:     audio.channels[channel].active = TRUE;
nkeynes@434:     if( audio.channels[channel].sample_format == AUDIO_FMT_ADPCM ) {
nkeynes@736:         audio.channels[channel].adpcm_step = 0;
nkeynes@736:         audio.channels[channel].adpcm_predict = 0;
nkeynes@934:         uint8_t data = ((uint8_t *)(aica_main_ram + audio.channels[channel].start))[0];
nkeynes@736:         adpcm_yamaha_decode_nibble( &audio.channels[channel], data & 0x0F );
nkeynes@434:     }
nkeynes@66: }