nkeynes@66 | 1 | /**
|
nkeynes@465 | 2 | * $Id: audio.c,v 1.11 2007-10-27 05:47:21 nkeynes Exp $
|
nkeynes@66 | 3 | *
|
nkeynes@66 | 4 | * Audio mixer core. Combines all the active streams into a single sound
|
nkeynes@66 | 5 | * buffer for output.
|
nkeynes@66 | 6 | *
|
nkeynes@66 | 7 | * Copyright (c) 2005 Nathan Keynes.
|
nkeynes@66 | 8 | *
|
nkeynes@66 | 9 | * This program is free software; you can redistribute it and/or modify
|
nkeynes@66 | 10 | * it under the terms of the GNU General Public License as published by
|
nkeynes@66 | 11 | * the Free Software Foundation; either version 2 of the License, or
|
nkeynes@66 | 12 | * (at your option) any later version.
|
nkeynes@66 | 13 | *
|
nkeynes@66 | 14 | * This program is distributed in the hope that it will be useful,
|
nkeynes@66 | 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
|
nkeynes@66 | 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
nkeynes@66 | 17 | * GNU General Public License for more details.
|
nkeynes@66 | 18 | */
|
nkeynes@66 | 19 |
|
nkeynes@66 | 20 | #include "aica/aica.h"
|
nkeynes@66 | 21 | #include "aica/audio.h"
|
nkeynes@66 | 22 | #include "glib/gmem.h"
|
nkeynes@66 | 23 | #include "dream.h"
|
nkeynes@66 | 24 | #include <assert.h>
|
nkeynes@66 | 25 | #include <string.h>
|
nkeynes@66 | 26 |
|
nkeynes@531 | 27 | audio_driver_t audio_driver_list[] = {
|
nkeynes@531 | 28 | #ifdef HAVE_ESOUND
|
nkeynes@531 | 29 | &audio_esd_driver,
|
nkeynes@531 | 30 | #endif
|
nkeynes@531 | 31 | &audio_null_driver,
|
nkeynes@531 | 32 | NULL };
|
nkeynes@531 | 33 |
|
nkeynes@66 | 34 | #define NUM_BUFFERS 3
|
nkeynes@434 | 35 | #define MS_PER_BUFFER 100
|
nkeynes@66 | 36 |
|
nkeynes@66 | 37 | #define BUFFER_EMPTY 0
|
nkeynes@66 | 38 | #define BUFFER_WRITING 1
|
nkeynes@66 | 39 | #define BUFFER_FULL 2
|
nkeynes@66 | 40 |
|
nkeynes@66 | 41 | struct audio_state {
|
nkeynes@66 | 42 | audio_buffer_t output_buffers[NUM_BUFFERS];
|
nkeynes@66 | 43 | int write_buffer;
|
nkeynes@66 | 44 | int read_buffer;
|
nkeynes@66 | 45 | uint32_t output_format;
|
nkeynes@66 | 46 | uint32_t output_rate;
|
nkeynes@66 | 47 | uint32_t output_sample_size;
|
nkeynes@465 | 48 | struct audio_channel channels[AUDIO_CHANNEL_COUNT];
|
nkeynes@66 | 49 | } audio;
|
nkeynes@66 | 50 |
|
nkeynes@66 | 51 | audio_driver_t audio_driver = NULL;
|
nkeynes@66 | 52 |
|
nkeynes@66 | 53 | #define NEXT_BUFFER() ((audio.write_buffer == NUM_BUFFERS-1) ? 0 : audio.write_buffer+1)
|
nkeynes@66 | 54 |
|
nkeynes@66 | 55 | extern char *arm_mem;
|
nkeynes@66 | 56 |
|
nkeynes@66 | 57 | /**
|
nkeynes@465 | 58 | * Preserve audio channel state only - don't bother saving the buffers
|
nkeynes@465 | 59 | */
|
nkeynes@465 | 60 | void audio_save_state( FILE *f )
|
nkeynes@465 | 61 | {
|
nkeynes@465 | 62 | fwrite( &audio.channels[0], sizeof(struct audio_channel), AUDIO_CHANNEL_COUNT, f );
|
nkeynes@465 | 63 | }
|
nkeynes@465 | 64 |
|
nkeynes@465 | 65 | int audio_load_state( FILE *f )
|
nkeynes@465 | 66 | {
|
nkeynes@465 | 67 | int read = fread( &audio.channels[0], sizeof(struct audio_channel), AUDIO_CHANNEL_COUNT, f );
|
nkeynes@465 | 68 | return (read == AUDIO_CHANNEL_COUNT ? 0 : -1 );
|
nkeynes@465 | 69 | }
|
nkeynes@465 | 70 |
|
nkeynes@531 | 71 | audio_driver_t get_audio_driver_by_name( const char *name )
|
nkeynes@531 | 72 | {
|
nkeynes@531 | 73 | int i;
|
nkeynes@531 | 74 | if( name == NULL ) {
|
nkeynes@531 | 75 | return audio_driver_list[0];
|
nkeynes@531 | 76 | }
|
nkeynes@531 | 77 | for( i=0; audio_driver_list[i] != NULL; i++ ) {
|
nkeynes@531 | 78 | if( strcasecmp( audio_driver_list[i]->name, name ) == 0 ) {
|
nkeynes@531 | 79 | return audio_driver_list[i];
|
nkeynes@531 | 80 | }
|
nkeynes@531 | 81 | }
|
nkeynes@531 | 82 |
|
nkeynes@531 | 83 | return NULL;
|
nkeynes@531 | 84 | }
|
nkeynes@531 | 85 |
|
nkeynes@465 | 86 | /**
|
nkeynes@66 | 87 | * Set the output driver, sample rate and format. Also initializes the
|
nkeynes@66 | 88 | * output buffers, flushing any current data and reallocating as
|
nkeynes@66 | 89 | * necessary.
|
nkeynes@66 | 90 | */
|
nkeynes@111 | 91 | gboolean audio_set_driver( audio_driver_t driver,
|
nkeynes@111 | 92 | uint32_t samplerate, int format )
|
nkeynes@66 | 93 | {
|
nkeynes@66 | 94 | uint32_t bytes_per_sample = 1;
|
nkeynes@66 | 95 | uint32_t samples_per_buffer;
|
nkeynes@66 | 96 | int i;
|
nkeynes@66 | 97 |
|
nkeynes@111 | 98 | if( audio_driver == NULL || driver != NULL ) {
|
nkeynes@111 | 99 | if( driver == NULL )
|
nkeynes@111 | 100 | driver = &audio_null_driver;
|
nkeynes@111 | 101 | if( driver != audio_driver ) {
|
nkeynes@111 | 102 | if( !driver->set_output_format( samplerate, format ) )
|
nkeynes@111 | 103 | return FALSE;
|
nkeynes@111 | 104 | audio_driver = driver;
|
nkeynes@111 | 105 | }
|
nkeynes@111 | 106 | }
|
nkeynes@111 | 107 |
|
nkeynes@66 | 108 | if( format & AUDIO_FMT_16BIT )
|
nkeynes@66 | 109 | bytes_per_sample = 2;
|
nkeynes@66 | 110 | if( format & AUDIO_FMT_STEREO )
|
nkeynes@66 | 111 | bytes_per_sample <<= 1;
|
nkeynes@66 | 112 | if( samplerate == audio.output_rate &&
|
nkeynes@66 | 113 | bytes_per_sample == audio.output_sample_size )
|
nkeynes@431 | 114 | return TRUE;
|
nkeynes@66 | 115 | samples_per_buffer = (samplerate * MS_PER_BUFFER / 1000);
|
nkeynes@66 | 116 | for( i=0; i<NUM_BUFFERS; i++ ) {
|
nkeynes@66 | 117 | if( audio.output_buffers[i] != NULL )
|
nkeynes@66 | 118 | free(audio.output_buffers[i]);
|
nkeynes@66 | 119 | audio.output_buffers[i] = g_malloc0( sizeof(struct audio_buffer) + samples_per_buffer * bytes_per_sample );
|
nkeynes@73 | 120 | audio.output_buffers[i]->length = samples_per_buffer * bytes_per_sample;
|
nkeynes@66 | 121 | audio.output_buffers[i]->posn = 0;
|
nkeynes@66 | 122 | audio.output_buffers[i]->status = BUFFER_EMPTY;
|
nkeynes@66 | 123 | }
|
nkeynes@66 | 124 | audio.output_format = format;
|
nkeynes@66 | 125 | audio.output_rate = samplerate;
|
nkeynes@66 | 126 | audio.output_sample_size = bytes_per_sample;
|
nkeynes@66 | 127 | audio.write_buffer = 0;
|
nkeynes@66 | 128 | audio.read_buffer = 0;
|
nkeynes@66 | 129 |
|
nkeynes@111 | 130 | return TRUE;
|
nkeynes@66 | 131 | }
|
nkeynes@66 | 132 |
|
nkeynes@66 | 133 | /**
|
nkeynes@66 | 134 | * Mark the current write buffer as full and prepare the next buffer for
|
nkeynes@66 | 135 | * writing. Returns the next buffer to write to.
|
nkeynes@66 | 136 | * If all buffers are full, returns NULL.
|
nkeynes@66 | 137 | */
|
nkeynes@66 | 138 | audio_buffer_t audio_next_write_buffer( )
|
nkeynes@66 | 139 | {
|
nkeynes@66 | 140 | audio_buffer_t result = NULL;
|
nkeynes@66 | 141 | audio_buffer_t current = audio.output_buffers[audio.write_buffer];
|
nkeynes@66 | 142 | current->status = BUFFER_FULL;
|
nkeynes@66 | 143 | if( audio.read_buffer == audio.write_buffer &&
|
nkeynes@66 | 144 | audio_driver->process_buffer( current ) ) {
|
nkeynes@66 | 145 | audio_next_read_buffer();
|
nkeynes@66 | 146 | }
|
nkeynes@66 | 147 | audio.write_buffer = NEXT_BUFFER();
|
nkeynes@66 | 148 | result = audio.output_buffers[audio.write_buffer];
|
nkeynes@66 | 149 | if( result->status == BUFFER_FULL )
|
nkeynes@66 | 150 | return NULL;
|
nkeynes@66 | 151 | else {
|
nkeynes@66 | 152 | result->status = BUFFER_WRITING;
|
nkeynes@66 | 153 | return result;
|
nkeynes@66 | 154 | }
|
nkeynes@66 | 155 | }
|
nkeynes@66 | 156 |
|
nkeynes@66 | 157 | /**
|
nkeynes@66 | 158 | * Mark the current read buffer as empty and return the next buffer for
|
nkeynes@66 | 159 | * reading. If there is no next buffer yet, returns NULL.
|
nkeynes@66 | 160 | */
|
nkeynes@66 | 161 | audio_buffer_t audio_next_read_buffer( )
|
nkeynes@66 | 162 | {
|
nkeynes@66 | 163 | audio_buffer_t current = audio.output_buffers[audio.read_buffer];
|
nkeynes@66 | 164 | assert( current->status == BUFFER_FULL );
|
nkeynes@66 | 165 | current->status = BUFFER_EMPTY;
|
nkeynes@66 | 166 | current->posn = 0;
|
nkeynes@66 | 167 | audio.read_buffer++;
|
nkeynes@66 | 168 | if( audio.read_buffer == NUM_BUFFERS )
|
nkeynes@66 | 169 | audio.read_buffer = 0;
|
nkeynes@66 | 170 |
|
nkeynes@66 | 171 | current = audio.output_buffers[audio.read_buffer];
|
nkeynes@66 | 172 | if( current->status == BUFFER_FULL )
|
nkeynes@66 | 173 | return current;
|
nkeynes@66 | 174 | else return NULL;
|
nkeynes@66 | 175 | }
|
nkeynes@66 | 176 |
|
nkeynes@66 | 177 | /*************************** ADPCM ***********************************/
|
nkeynes@66 | 178 |
|
nkeynes@66 | 179 | /**
|
nkeynes@66 | 180 | * The following section borrows heavily from ffmpeg, which is
|
nkeynes@66 | 181 | * copyright (c) 2001-2003 by the fine folks at the ffmpeg project,
|
nkeynes@66 | 182 | * distributed under the GPL version 2 or later.
|
nkeynes@66 | 183 | */
|
nkeynes@66 | 184 |
|
nkeynes@66 | 185 | #define CLAMP_TO_SHORT(value) \
|
nkeynes@66 | 186 | if (value > 32767) \
|
nkeynes@66 | 187 | value = 32767; \
|
nkeynes@66 | 188 | else if (value < -32768) \
|
nkeynes@66 | 189 | value = -32768; \
|
nkeynes@66 | 190 |
|
nkeynes@66 | 191 | static const int yamaha_indexscale[] = {
|
nkeynes@66 | 192 | 230, 230, 230, 230, 307, 409, 512, 614,
|
nkeynes@66 | 193 | 230, 230, 230, 230, 307, 409, 512, 614
|
nkeynes@66 | 194 | };
|
nkeynes@66 | 195 |
|
nkeynes@66 | 196 | static const int yamaha_difflookup[] = {
|
nkeynes@66 | 197 | 1, 3, 5, 7, 9, 11, 13, 15,
|
nkeynes@66 | 198 | -1, -3, -5, -7, -9, -11, -13, -15
|
nkeynes@66 | 199 | };
|
nkeynes@66 | 200 |
|
nkeynes@66 | 201 | static inline short adpcm_yamaha_decode_nibble( audio_channel_t c,
|
nkeynes@66 | 202 | unsigned char nibble )
|
nkeynes@66 | 203 | {
|
nkeynes@66 | 204 | if( c->adpcm_step == 0 ) {
|
nkeynes@66 | 205 | c->adpcm_predict = 0;
|
nkeynes@66 | 206 | c->adpcm_step = 127;
|
nkeynes@66 | 207 | }
|
nkeynes@66 | 208 |
|
nkeynes@66 | 209 | c->adpcm_predict += (c->adpcm_step * yamaha_difflookup[nibble]) >> 3;
|
nkeynes@66 | 210 | CLAMP_TO_SHORT(c->adpcm_predict);
|
nkeynes@66 | 211 | c->adpcm_step = (c->adpcm_step * yamaha_indexscale[nibble]) >> 8;
|
nkeynes@66 | 212 | c->adpcm_step = CLAMP(c->adpcm_step, 127, 24567);
|
nkeynes@66 | 213 | return c->adpcm_predict;
|
nkeynes@66 | 214 | }
|
nkeynes@66 | 215 |
|
nkeynes@66 | 216 | /*************************** Sample mixer *****************************/
|
nkeynes@66 | 217 |
|
nkeynes@66 | 218 | /**
|
nkeynes@66 | 219 | * Mix a single output sample.
|
nkeynes@66 | 220 | */
|
nkeynes@73 | 221 | void audio_mix_samples( int num_samples )
|
nkeynes@66 | 222 | {
|
nkeynes@66 | 223 | int i, j;
|
nkeynes@73 | 224 | int32_t result_buf[num_samples][2];
|
nkeynes@73 | 225 |
|
nkeynes@73 | 226 | memset( &result_buf, 0, sizeof(result_buf) );
|
nkeynes@66 | 227 |
|
nkeynes@465 | 228 | for( i=0; i < AUDIO_CHANNEL_COUNT; i++ ) {
|
nkeynes@66 | 229 | audio_channel_t channel = &audio.channels[i];
|
nkeynes@66 | 230 | if( channel->active ) {
|
nkeynes@66 | 231 | int32_t sample;
|
nkeynes@82 | 232 | int vol_left = (channel->vol * (32 - channel->pan)) >> 5;
|
nkeynes@82 | 233 | int vol_right = (channel->vol * (channel->pan + 1)) >> 5;
|
nkeynes@66 | 234 | switch( channel->sample_format ) {
|
nkeynes@66 | 235 | case AUDIO_FMT_16BIT:
|
nkeynes@73 | 236 | for( j=0; j<num_samples; j++ ) {
|
nkeynes@434 | 237 | sample = ((int16_t *)(arm_mem + channel->start))[channel->posn];
|
nkeynes@82 | 238 | result_buf[j][0] += sample * vol_left;
|
nkeynes@82 | 239 | result_buf[j][1] += sample * vol_right;
|
nkeynes@73 | 240 |
|
nkeynes@73 | 241 | channel->posn_left += channel->sample_rate;
|
nkeynes@73 | 242 | while( channel->posn_left > audio.output_rate ) {
|
nkeynes@73 | 243 | channel->posn_left -= audio.output_rate;
|
nkeynes@73 | 244 | channel->posn++;
|
nkeynes@73 | 245 |
|
nkeynes@73 | 246 | if( channel->posn == channel->end ) {
|
nkeynes@463 | 247 | if( channel->loop ) {
|
nkeynes@73 | 248 | channel->posn = channel->loop_start;
|
nkeynes@463 | 249 | channel->loop = LOOP_LOOPED;
|
nkeynes@463 | 250 | } else {
|
nkeynes@73 | 251 | audio_stop_channel(i);
|
nkeynes@73 | 252 | j = num_samples;
|
nkeynes@73 | 253 | break;
|
nkeynes@73 | 254 | }
|
nkeynes@73 | 255 | }
|
nkeynes@73 | 256 | }
|
nkeynes@73 | 257 | }
|
nkeynes@66 | 258 | break;
|
nkeynes@66 | 259 | case AUDIO_FMT_8BIT:
|
nkeynes@73 | 260 | for( j=0; j<num_samples; j++ ) {
|
nkeynes@434 | 261 | sample = ((int8_t *)(arm_mem + channel->start))[channel->posn] << 8;
|
nkeynes@82 | 262 | result_buf[j][0] += sample * vol_left;
|
nkeynes@82 | 263 | result_buf[j][1] += sample * vol_right;
|
nkeynes@73 | 264 |
|
nkeynes@73 | 265 | channel->posn_left += channel->sample_rate;
|
nkeynes@73 | 266 | while( channel->posn_left > audio.output_rate ) {
|
nkeynes@73 | 267 | channel->posn_left -= audio.output_rate;
|
nkeynes@73 | 268 | channel->posn++;
|
nkeynes@73 | 269 |
|
nkeynes@73 | 270 | if( channel->posn == channel->end ) {
|
nkeynes@463 | 271 | if( channel->loop ) {
|
nkeynes@73 | 272 | channel->posn = channel->loop_start;
|
nkeynes@463 | 273 | channel->loop = LOOP_LOOPED;
|
nkeynes@463 | 274 | } else {
|
nkeynes@73 | 275 | audio_stop_channel(i);
|
nkeynes@73 | 276 | j = num_samples;
|
nkeynes@73 | 277 | break;
|
nkeynes@73 | 278 | }
|
nkeynes@73 | 279 | }
|
nkeynes@73 | 280 | }
|
nkeynes@73 | 281 | }
|
nkeynes@66 | 282 | break;
|
nkeynes@66 | 283 | case AUDIO_FMT_ADPCM:
|
nkeynes@73 | 284 | for( j=0; j<num_samples; j++ ) {
|
nkeynes@73 | 285 | sample = (int16_t)channel->adpcm_predict;
|
nkeynes@82 | 286 | result_buf[j][0] += sample * vol_left;
|
nkeynes@82 | 287 | result_buf[j][1] += sample * vol_right;
|
nkeynes@73 | 288 | channel->posn_left += channel->sample_rate;
|
nkeynes@73 | 289 | while( channel->posn_left > audio.output_rate ) {
|
nkeynes@73 | 290 | channel->posn_left -= audio.output_rate;
|
nkeynes@434 | 291 | channel->posn++;
|
nkeynes@434 | 292 | if( channel->posn == channel->end ) {
|
nkeynes@434 | 293 | if( channel->loop ) {
|
nkeynes@434 | 294 | channel->posn = channel->loop_start;
|
nkeynes@463 | 295 | channel->loop = LOOP_LOOPED;
|
nkeynes@434 | 296 | channel->adpcm_predict = 0;
|
nkeynes@434 | 297 | channel->adpcm_step = 0;
|
nkeynes@434 | 298 | } else {
|
nkeynes@434 | 299 | audio_stop_channel(i);
|
nkeynes@434 | 300 | j = num_samples;
|
nkeynes@73 | 301 | break;
|
nkeynes@73 | 302 | }
|
nkeynes@434 | 303 | }
|
nkeynes@434 | 304 | uint8_t data = ((uint8_t *)(arm_mem + channel->start))[channel->posn>>1];
|
nkeynes@434 | 305 | if( channel->posn&1 ) {
|
nkeynes@434 | 306 | adpcm_yamaha_decode_nibble( channel, (data >> 4) & 0x0F );
|
nkeynes@434 | 307 | } else {
|
nkeynes@73 | 308 | adpcm_yamaha_decode_nibble( channel, data & 0x0F );
|
nkeynes@73 | 309 | }
|
nkeynes@73 | 310 | }
|
nkeynes@73 | 311 | }
|
nkeynes@73 | 312 | break;
|
nkeynes@66 | 313 | default:
|
nkeynes@73 | 314 | break;
|
nkeynes@66 | 315 | }
|
nkeynes@66 | 316 | }
|
nkeynes@66 | 317 | }
|
nkeynes@73 | 318 |
|
nkeynes@66 | 319 | /* Down-render to the final output format */
|
nkeynes@73 | 320 |
|
nkeynes@66 | 321 | if( audio.output_format & AUDIO_FMT_16BIT ) {
|
nkeynes@73 | 322 | audio_buffer_t buf = audio.output_buffers[audio.write_buffer];
|
nkeynes@73 | 323 | uint16_t *data = (uint16_t *)&buf->data[buf->posn];
|
nkeynes@73 | 324 | for( j=0; j < num_samples; j++ ) {
|
nkeynes@82 | 325 | *data++ = (int16_t)(result_buf[j][0] >> 6);
|
nkeynes@82 | 326 | *data++ = (int16_t)(result_buf[j][1] >> 6);
|
nkeynes@73 | 327 | buf->posn += 4;
|
nkeynes@73 | 328 | if( buf->posn == buf->length ) {
|
nkeynes@73 | 329 | audio_next_write_buffer();
|
nkeynes@73 | 330 | buf = audio.output_buffers[audio.write_buffer];
|
nkeynes@73 | 331 | data = (uint16_t *)&buf->data[0];
|
nkeynes@73 | 332 | }
|
nkeynes@73 | 333 | }
|
nkeynes@66 | 334 | } else {
|
nkeynes@73 | 335 | audio_buffer_t buf = audio.output_buffers[audio.write_buffer];
|
nkeynes@73 | 336 | uint8_t *data = (uint8_t *)&buf->data[buf->posn];
|
nkeynes@73 | 337 | for( j=0; j < num_samples; j++ ) {
|
nkeynes@73 | 338 | *data++ = (uint8_t)(result_buf[j][0] >> 16);
|
nkeynes@73 | 339 | *data++ = (uint8_t)(result_buf[j][1] >> 16);
|
nkeynes@73 | 340 | buf->posn += 2;
|
nkeynes@73 | 341 | if( buf->posn == buf->length ) {
|
nkeynes@73 | 342 | audio_next_write_buffer();
|
nkeynes@73 | 343 | buf = audio.output_buffers[audio.write_buffer];
|
nkeynes@73 | 344 | data = (uint8_t *)&buf->data[0];
|
nkeynes@73 | 345 | }
|
nkeynes@73 | 346 | }
|
nkeynes@66 | 347 | }
|
nkeynes@66 | 348 | }
|
nkeynes@66 | 349 |
|
nkeynes@66 | 350 | /********************** Internal AICA calls ***************************/
|
nkeynes@66 | 351 |
|
nkeynes@66 | 352 | audio_channel_t audio_get_channel( int channel )
|
nkeynes@66 | 353 | {
|
nkeynes@66 | 354 | return &audio.channels[channel];
|
nkeynes@66 | 355 | }
|
nkeynes@66 | 356 |
|
nkeynes@434 | 357 | void audio_start_stop_channel( int channel, gboolean start )
|
nkeynes@434 | 358 | {
|
nkeynes@434 | 359 | if( audio.channels[channel].active ) {
|
nkeynes@434 | 360 | if( !start ) {
|
nkeynes@434 | 361 | audio_stop_channel(channel);
|
nkeynes@434 | 362 | }
|
nkeynes@434 | 363 | } else if( start ) {
|
nkeynes@434 | 364 | audio_start_channel(channel);
|
nkeynes@434 | 365 | }
|
nkeynes@434 | 366 | }
|
nkeynes@434 | 367 |
|
nkeynes@66 | 368 | void audio_stop_channel( int channel )
|
nkeynes@66 | 369 | {
|
nkeynes@66 | 370 | audio.channels[channel].active = FALSE;
|
nkeynes@66 | 371 | }
|
nkeynes@66 | 372 |
|
nkeynes@66 | 373 |
|
nkeynes@66 | 374 | void audio_start_channel( int channel )
|
nkeynes@66 | 375 | {
|
nkeynes@66 | 376 | audio.channels[channel].posn = 0;
|
nkeynes@66 | 377 | audio.channels[channel].posn_left = 0;
|
nkeynes@66 | 378 | audio.channels[channel].active = TRUE;
|
nkeynes@434 | 379 | if( audio.channels[channel].sample_format == AUDIO_FMT_ADPCM ) {
|
nkeynes@434 | 380 | audio.channels[channel].adpcm_step = 0;
|
nkeynes@434 | 381 | audio.channels[channel].adpcm_predict = 0;
|
nkeynes@434 | 382 | uint8_t data = ((uint8_t *)(arm_mem + audio.channels[channel].start))[0];
|
nkeynes@434 | 383 | adpcm_yamaha_decode_nibble( &audio.channels[channel], data & 0x0F );
|
nkeynes@434 | 384 | }
|
nkeynes@66 | 385 | }
|