1/* 2 SDL - Simple DirectMedia Layer 3 Copyright (C) 1997-2012 Sam Lantinga 4 5 This library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Library General Public 7 License as published by the Free Software Foundation; either 8 version 2 of the License, or (at your option) any later version. 9 10 This library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Library General Public License for more details. 14 15 You should have received a copy of the GNU Library General Public 16 License along with this library; if not, write to the Free 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 19 Sam Lantinga 20 slouken@libsdl.org 21*/ 22#include "SDL_config.h" 23 24/* Allow access to a raw mixing buffer */ 25 26#include <sys/types.h> 27#include <signal.h> /* For kill() */ 28 29#include "SDL_timer.h" 30#include "SDL_audio.h" 31#include "../SDL_audiomem.h" 32#include "../SDL_audio_c.h" 33#include "SDL_alsa_audio.h" 34 35#ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC 36#include "SDL_name.h" 37#include "SDL_loadso.h" 38#else 39#define SDL_NAME(X) X 40#endif 41 42 43/* The tag name used by ALSA audio */ 44#define DRIVER_NAME "alsa" 45 46/* Audio driver functions */ 47static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec); 48static void ALSA_WaitAudio(_THIS); 49static void ALSA_PlayAudio(_THIS); 50static Uint8 *ALSA_GetAudioBuf(_THIS); 51static void ALSA_CloseAudio(_THIS); 52 53#ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC 54 55static const char *alsa_library = SDL_AUDIO_DRIVER_ALSA_DYNAMIC; 56static void *alsa_handle = NULL; 57static int alsa_loaded = 0; 58 59static int (*SDL_NAME(snd_pcm_open))(snd_pcm_t **pcm, const char *name, snd_pcm_stream_t stream, int mode); 60static int (*SDL_NAME(snd_pcm_close))(snd_pcm_t *pcm); 61static snd_pcm_sframes_t (*SDL_NAME(snd_pcm_writei))(snd_pcm_t *pcm, const void *buffer, snd_pcm_uframes_t size); 62static int (*SDL_NAME(snd_pcm_recover))(snd_pcm_t *pcm, int err, int silent); 63static int (*SDL_NAME(snd_pcm_prepare))(snd_pcm_t *pcm); 64static int (*SDL_NAME(snd_pcm_drain))(snd_pcm_t *pcm); 65static const char *(*SDL_NAME(snd_strerror))(int errnum); 66static size_t (*SDL_NAME(snd_pcm_hw_params_sizeof))(void); 67static size_t (*SDL_NAME(snd_pcm_sw_params_sizeof))(void); 68static void (*SDL_NAME(snd_pcm_hw_params_copy))(snd_pcm_hw_params_t *dst, const snd_pcm_hw_params_t *src); 69static int (*SDL_NAME(snd_pcm_hw_params_any))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params); 70static int (*SDL_NAME(snd_pcm_hw_params_set_access))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t access); 71static int (*SDL_NAME(snd_pcm_hw_params_set_format))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t val); 72static int (*SDL_NAME(snd_pcm_hw_params_set_channels))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val); 73static int (*SDL_NAME(snd_pcm_hw_params_get_channels))(const snd_pcm_hw_params_t *params, unsigned int *val); 74static int (*SDL_NAME(snd_pcm_hw_params_set_rate_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir); 75static int (*SDL_NAME(snd_pcm_hw_params_set_period_size_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir); 76static int (*SDL_NAME(snd_pcm_hw_params_get_period_size))(const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir); 77static int (*SDL_NAME(snd_pcm_hw_params_set_periods_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir); 78static int (*SDL_NAME(snd_pcm_hw_params_get_periods))(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir); 79static int (*SDL_NAME(snd_pcm_hw_params_set_buffer_size_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val); 80static int (*SDL_NAME(snd_pcm_hw_params_get_buffer_size))(const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val); 81static int (*SDL_NAME(snd_pcm_hw_params))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params); 82/* 83*/ 84static 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); 85static int (*SDL_NAME(snd_pcm_sw_params_current))(snd_pcm_t *pcm, snd_pcm_sw_params_t *swparams); 86static 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); 87static int (*SDL_NAME(snd_pcm_sw_params))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params); 88static int (*SDL_NAME(snd_pcm_nonblock))(snd_pcm_t *pcm, int nonblock); 89static int (*SDL_NAME(snd_pcm_wait))(snd_pcm_t *pcm, int timeout); 90#define snd_pcm_hw_params_sizeof SDL_NAME(snd_pcm_hw_params_sizeof) 91#define snd_pcm_sw_params_sizeof SDL_NAME(snd_pcm_sw_params_sizeof) 92 93/* cast funcs to char* first, to please GCC's strict aliasing rules. */ 94static struct { 95 const char *name; 96 void **func; 97} alsa_functions[] = { 98 { "snd_pcm_open", (void**)(char*)&SDL_NAME(snd_pcm_open) }, 99 { "snd_pcm_close", (void**)(char*)&SDL_NAME(snd_pcm_close) }, 100 { "snd_pcm_writei", (void**)(char*)&SDL_NAME(snd_pcm_writei) }, 101 { "snd_pcm_recover", (void**)(char*)&SDL_NAME(snd_pcm_recover) }, 102 { "snd_pcm_prepare", (void**)(char*)&SDL_NAME(snd_pcm_prepare) }, 103 { "snd_pcm_drain", (void**)(char*)&SDL_NAME(snd_pcm_drain) }, 104 { "snd_strerror", (void**)(char*)&SDL_NAME(snd_strerror) }, 105 { "snd_pcm_hw_params_sizeof", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_sizeof) }, 106 { "snd_pcm_sw_params_sizeof", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_sizeof) }, 107 { "snd_pcm_hw_params_copy", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_copy) }, 108 { "snd_pcm_hw_params_any", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_any) }, 109 { "snd_pcm_hw_params_set_access", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_access) }, 110 { "snd_pcm_hw_params_set_format", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_format) }, 111 { "snd_pcm_hw_params_set_channels", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_channels) }, 112 { "snd_pcm_hw_params_get_channels", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_channels) }, 113 { "snd_pcm_hw_params_set_rate_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_rate_near) }, 114 { "snd_pcm_hw_params_set_period_size_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_period_size_near) }, 115 { "snd_pcm_hw_params_get_period_size", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_period_size) }, 116 { "snd_pcm_hw_params_set_periods_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_periods_near) }, 117 { "snd_pcm_hw_params_get_periods", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_periods) }, 118 { "snd_pcm_hw_params_set_buffer_size_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_buffer_size_near) }, 119 { "snd_pcm_hw_params_get_buffer_size", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_buffer_size) }, 120 { "snd_pcm_hw_params", (void**)(char*)&SDL_NAME(snd_pcm_hw_params) }, 121 { "snd_pcm_sw_params_set_avail_min", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_avail_min) }, 122 { "snd_pcm_sw_params_current", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_current) }, 123 { "snd_pcm_sw_params_set_start_threshold", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_start_threshold) }, 124 { "snd_pcm_sw_params", (void**)(char*)&SDL_NAME(snd_pcm_sw_params) }, 125 { "snd_pcm_nonblock", (void**)(char*)&SDL_NAME(snd_pcm_nonblock) }, 126 { "snd_pcm_wait", (void**)(char*)&SDL_NAME(snd_pcm_wait) }, 127}; 128 129static void UnloadALSALibrary(void) { 130 if (alsa_loaded) { 131 SDL_UnloadObject(alsa_handle); 132 alsa_handle = NULL; 133 alsa_loaded = 0; 134 } 135} 136 137static int LoadALSALibrary(void) { 138 int i, retval = -1; 139 140 alsa_handle = SDL_LoadObject(alsa_library); 141 if (alsa_handle) { 142 alsa_loaded = 1; 143 retval = 0; 144 for (i = 0; i < SDL_arraysize(alsa_functions); i++) { 145 *alsa_functions[i].func = SDL_LoadFunction(alsa_handle,alsa_functions[i].name); 146 if (!*alsa_functions[i].func) { 147 retval = -1; 148 UnloadALSALibrary(); 149 break; 150 } 151 } 152 } 153 return retval; 154} 155 156#else 157 158static void UnloadALSALibrary(void) { 159 return; 160} 161 162static int LoadALSALibrary(void) { 163 return 0; 164} 165 166#endif /* SDL_AUDIO_DRIVER_ALSA_DYNAMIC */ 167 168static const char *get_audio_device(int channels) 169{ 170 const char *device; 171 172 device = SDL_getenv("AUDIODEV"); /* Is there a standard variable name? */ 173 if ( device == NULL ) { 174 switch (channels) { 175 case 6: 176 device = "plug:surround51"; 177 break; 178 case 4: 179 device = "plug:surround40"; 180 break; 181 default: 182 device = "default"; 183 break; 184 } 185 } 186 return device; 187} 188 189/* Audio driver bootstrap functions */ 190 191static int Audio_Available(void) 192{ 193 int available; 194 int status; 195 snd_pcm_t *handle; 196 197 available = 0; 198 if (LoadALSALibrary() < 0) { 199 return available; 200 } 201 status = SDL_NAME(snd_pcm_open)(&handle, get_audio_device(2), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK); 202 if ( status >= 0 ) { 203 available = 1; 204 SDL_NAME(snd_pcm_close)(handle); 205 } 206 UnloadALSALibrary(); 207 return(available); 208} 209 210static void Audio_DeleteDevice(SDL_AudioDevice *device) 211{ 212 SDL_free(device->hidden); 213 SDL_free(device); 214 UnloadALSALibrary(); 215} 216 217static SDL_AudioDevice *Audio_CreateDevice(int devindex) 218{ 219 SDL_AudioDevice *this; 220 221 /* Initialize all variables that we clean on shutdown */ 222 LoadALSALibrary(); 223 this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice)); 224 if ( this ) { 225 SDL_memset(this, 0, (sizeof *this)); 226 this->hidden = (struct SDL_PrivateAudioData *) 227 SDL_malloc((sizeof *this->hidden)); 228 } 229 if ( (this == NULL) || (this->hidden == NULL) ) { 230 SDL_OutOfMemory(); 231 if ( this ) { 232 SDL_free(this); 233 } 234 return(0); 235 } 236 SDL_memset(this->hidden, 0, (sizeof *this->hidden)); 237 238 /* Set the function pointers */ 239 this->OpenAudio = ALSA_OpenAudio; 240 this->WaitAudio = ALSA_WaitAudio; 241 this->PlayAudio = ALSA_PlayAudio; 242 this->GetAudioBuf = ALSA_GetAudioBuf; 243 this->CloseAudio = ALSA_CloseAudio; 244 245 this->free = Audio_DeleteDevice; 246 247 return this; 248} 249 250AudioBootStrap ALSA_bootstrap = { 251 DRIVER_NAME, "ALSA PCM audio", 252 Audio_Available, Audio_CreateDevice 253}; 254 255/* This function waits until it is possible to write a full sound buffer */ 256static void ALSA_WaitAudio(_THIS) 257{ 258 /* We're in blocking mode, so there's nothing to do here */ 259} 260 261 262/* 263 * http://bugzilla.libsdl.org/show_bug.cgi?id=110 264 * "For Linux ALSA, this is FL-FR-RL-RR-C-LFE 265 * and for Windows DirectX [and CoreAudio], this is FL-FR-C-LFE-RL-RR" 266 */ 267#define SWIZ6(T) \ 268 T *ptr = (T *) mixbuf; \ 269 Uint32 i; \ 270 for (i = 0; i < this->spec.samples; i++, ptr += 6) { \ 271 T tmp; \ 272 tmp = ptr[2]; ptr[2] = ptr[4]; ptr[4] = tmp; \ 273 tmp = ptr[3]; ptr[3] = ptr[5]; ptr[5] = tmp; \ 274 } 275 276static __inline__ void swizzle_alsa_channels_6_64bit(_THIS) { SWIZ6(Uint64); } 277static __inline__ void swizzle_alsa_channels_6_32bit(_THIS) { SWIZ6(Uint32); } 278static __inline__ void swizzle_alsa_channels_6_16bit(_THIS) { SWIZ6(Uint16); } 279static __inline__ void swizzle_alsa_channels_6_8bit(_THIS) { SWIZ6(Uint8); } 280 281#undef SWIZ6 282 283 284/* 285 * Called right before feeding this->mixbuf to the hardware. Swizzle channels 286 * from Windows/Mac order to the format alsalib will want. 287 */ 288static __inline__ void swizzle_alsa_channels(_THIS) 289{ 290 if (this->spec.channels == 6) { 291 const Uint16 fmtsize = (this->spec.format & 0xFF); /* bits/channel. */ 292 if (fmtsize == 16) 293 swizzle_alsa_channels_6_16bit(this); 294 else if (fmtsize == 8) 295 swizzle_alsa_channels_6_8bit(this); 296 else if (fmtsize == 32) 297 swizzle_alsa_channels_6_32bit(this); 298 else if (fmtsize == 64) 299 swizzle_alsa_channels_6_64bit(this); 300 } 301 302 /* !!! FIXME: update this for 7.1 if needed, later. */ 303} 304 305 306static void ALSA_PlayAudio(_THIS) 307{ 308 int status; 309 snd_pcm_uframes_t frames_left; 310 const Uint8 *sample_buf = (const Uint8 *) mixbuf; 311 const int frame_size = (((int) (this->spec.format & 0xFF)) / 8) * this->spec.channels; 312 313 swizzle_alsa_channels(this); 314 315 frames_left = ((snd_pcm_uframes_t) this->spec.samples); 316 317 while ( frames_left > 0 && this->enabled ) { 318 /* This works, but needs more testing before going live */ 319 /*SDL_NAME(snd_pcm_wait)(pcm_handle, -1);*/ 320 321 status = SDL_NAME(snd_pcm_writei)(pcm_handle, sample_buf, frames_left); 322 if ( status < 0 ) { 323 if ( status == -EAGAIN ) { 324 /* Apparently snd_pcm_recover() doesn't handle this case - does it assume snd_pcm_wait() above? */ 325 SDL_Delay(1); 326 continue; 327 } 328 status = SDL_NAME(snd_pcm_recover)(pcm_handle, status, 0); 329 if ( status < 0 ) { 330 /* Hmm, not much we can do - abort */ 331 fprintf(stderr, "ALSA write failed (unrecoverable): %s\n", SDL_NAME(snd_strerror)(status)); 332 this->enabled = 0; 333 return; 334 } 335 continue; 336 } 337 sample_buf += status * frame_size; 338 frames_left -= status; 339 } 340} 341 342static Uint8 *ALSA_GetAudioBuf(_THIS) 343{ 344 return(mixbuf); 345} 346 347static void ALSA_CloseAudio(_THIS) 348{ 349 if ( mixbuf != NULL ) { 350 SDL_FreeAudioMem(mixbuf); 351 mixbuf = NULL; 352 } 353 if ( pcm_handle ) { 354 SDL_NAME(snd_pcm_drain)(pcm_handle); 355 SDL_NAME(snd_pcm_close)(pcm_handle); 356 pcm_handle = NULL; 357 } 358} 359 360static int ALSA_finalize_hardware(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *hwparams, int override) 361{ 362 int status; 363 snd_pcm_uframes_t bufsize; 364 365 /* "set" the hardware with the desired parameters */ 366 status = SDL_NAME(snd_pcm_hw_params)(pcm_handle, hwparams); 367 if ( status < 0 ) { 368 return(-1); 369 } 370 371 /* Get samples for the actual buffer size */ 372 status = SDL_NAME(snd_pcm_hw_params_get_buffer_size)(hwparams, &bufsize); 373 if ( status < 0 ) { 374 return(-1); 375 } 376 if ( !override && bufsize != spec->samples * 2 ) { 377 return(-1); 378 } 379 380 /* FIXME: Is this safe to do? */ 381 spec->samples = bufsize / 2; 382 383 /* This is useful for debugging */ 384 if ( getenv("SDL_AUDIO_ALSA_DEBUG") ) { 385 snd_pcm_uframes_t persize = 0; 386 unsigned int periods = 0; 387 388 SDL_NAME(snd_pcm_hw_params_get_period_size)(hwparams, &persize, NULL); 389 SDL_NAME(snd_pcm_hw_params_get_periods)(hwparams, &periods, NULL); 390 391 fprintf(stderr, "ALSA: period size = %ld, periods = %u, buffer size = %lu\n", persize, periods, bufsize); 392 } 393 return(0); 394} 395 396static int ALSA_set_period_size(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *params, int override) 397{ 398 const char *env; 399 int status; 400 snd_pcm_hw_params_t *hwparams; 401 snd_pcm_uframes_t frames; 402 unsigned int periods; 403 404 /* Copy the hardware parameters for this setup */ 405 snd_pcm_hw_params_alloca(&hwparams); 406 SDL_NAME(snd_pcm_hw_params_copy)(hwparams, params); 407 408 if ( !override ) { 409 env = getenv("SDL_AUDIO_ALSA_SET_PERIOD_SIZE"); 410 if ( env ) { 411 override = SDL_atoi(env); 412 if ( override == 0 ) { 413 return(-1); 414 } 415 } 416 } 417 418 frames = spec->samples; 419 status = SDL_NAME(snd_pcm_hw_params_set_period_size_near)(pcm_handle, hwparams, &frames, NULL); 420 if ( status < 0 ) { 421 return(-1); 422 } 423 424 periods = 2; 425 status = SDL_NAME(snd_pcm_hw_params_set_periods_near)(pcm_handle, hwparams, &periods, NULL); 426 if ( status < 0 ) { 427 return(-1); 428 } 429 430 return ALSA_finalize_hardware(this, spec, hwparams, override); 431} 432 433static int ALSA_set_buffer_size(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *params, int override) 434{ 435 const char *env; 436 int status; 437 snd_pcm_hw_params_t *hwparams; 438 snd_pcm_uframes_t frames; 439 440 /* Copy the hardware parameters for this setup */ 441 snd_pcm_hw_params_alloca(&hwparams); 442 SDL_NAME(snd_pcm_hw_params_copy)(hwparams, params); 443 444 if ( !override ) { 445 env = getenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE"); 446 if ( env ) { 447 override = SDL_atoi(env); 448 if ( override == 0 ) { 449 return(-1); 450 } 451 } 452 } 453 454 frames = spec->samples * 2; 455 status = SDL_NAME(snd_pcm_hw_params_set_buffer_size_near)(pcm_handle, hwparams, &frames); 456 if ( status < 0 ) { 457 return(-1); 458 } 459 460 return ALSA_finalize_hardware(this, spec, hwparams, override); 461} 462 463static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec) 464{ 465 int status; 466 snd_pcm_hw_params_t *hwparams; 467 snd_pcm_sw_params_t *swparams; 468 snd_pcm_format_t format; 469 unsigned int rate; 470 unsigned int channels; 471 Uint16 test_format; 472 473 /* Open the audio device */ 474 /* Name of device should depend on # channels in spec */ 475 status = SDL_NAME(snd_pcm_open)(&pcm_handle, get_audio_device(spec->channels), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK); 476 477 if ( status < 0 ) { 478 SDL_SetError("Couldn't open audio device: %s", SDL_NAME(snd_strerror)(status)); 479 return(-1); 480 } 481 482 /* Figure out what the hardware is capable of */ 483 snd_pcm_hw_params_alloca(&hwparams); 484 status = SDL_NAME(snd_pcm_hw_params_any)(pcm_handle, hwparams); 485 if ( status < 0 ) { 486 SDL_SetError("Couldn't get hardware config: %s", SDL_NAME(snd_strerror)(status)); 487 ALSA_CloseAudio(this); 488 return(-1); 489 } 490 491 /* SDL only uses interleaved sample output */ 492 status = SDL_NAME(snd_pcm_hw_params_set_access)(pcm_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); 493 if ( status < 0 ) { 494 SDL_SetError("Couldn't set interleaved access: %s", SDL_NAME(snd_strerror)(status)); 495 ALSA_CloseAudio(this); 496 return(-1); 497 } 498 499 /* Try for a closest match on audio format */ 500 status = -1; 501 for ( test_format = SDL_FirstAudioFormat(spec->format); 502 test_format && (status < 0); ) { 503 switch ( test_format ) { 504 case AUDIO_U8: 505 format = SND_PCM_FORMAT_U8; 506 break; 507 case AUDIO_S8: 508 format = SND_PCM_FORMAT_S8; 509 break; 510 case AUDIO_S16LSB: 511 format = SND_PCM_FORMAT_S16_LE; 512 break; 513 case AUDIO_S16MSB: 514 format = SND_PCM_FORMAT_S16_BE; 515 break; 516 case AUDIO_U16LSB: 517 format = SND_PCM_FORMAT_U16_LE; 518 break; 519 case AUDIO_U16MSB: 520 format = SND_PCM_FORMAT_U16_BE; 521 break; 522 default: 523 format = 0; 524 break; 525 } 526 if ( format != 0 ) { 527 status = SDL_NAME(snd_pcm_hw_params_set_format)(pcm_handle, hwparams, format); 528 } 529 if ( status < 0 ) { 530 test_format = SDL_NextAudioFormat(); 531 } 532 } 533 if ( status < 0 ) { 534 SDL_SetError("Couldn't find any hardware audio formats"); 535 ALSA_CloseAudio(this); 536 return(-1); 537 } 538 spec->format = test_format; 539 540 /* Set the number of channels */ 541 status = SDL_NAME(snd_pcm_hw_params_set_channels)(pcm_handle, hwparams, spec->channels); 542 channels = spec->channels; 543 if ( status < 0 ) { 544 status = SDL_NAME(snd_pcm_hw_params_get_channels)(hwparams, &channels); 545 if ( status < 0 ) { 546 SDL_SetError("Couldn't set audio channels"); 547 ALSA_CloseAudio(this); 548 return(-1); 549 } 550 spec->channels = channels; 551 } 552 553 /* Set the audio rate */ 554 rate = spec->freq; 555 556 status = SDL_NAME(snd_pcm_hw_params_set_rate_near)(pcm_handle, hwparams, &rate, NULL); 557 if ( status < 0 ) { 558 SDL_SetError("Couldn't set audio frequency: %s", SDL_NAME(snd_strerror)(status)); 559 ALSA_CloseAudio(this); 560 return(-1); 561 } 562 spec->freq = rate; 563 564 /* Set the buffer size, in samples */ 565 if ( ALSA_set_period_size(this, spec, hwparams, 0) < 0 && 566 ALSA_set_buffer_size(this, spec, hwparams, 0) < 0 ) { 567 /* Failed to set desired buffer size, do the best you can... */ 568 if ( ALSA_set_period_size(this, spec, hwparams, 1) < 0 ) { 569 SDL_SetError("Couldn't set hardware audio parameters: %s", SDL_NAME(snd_strerror)(status)); 570 ALSA_CloseAudio(this); 571 return(-1); 572 } 573 } 574 575 /* Set the software parameters */ 576 snd_pcm_sw_params_alloca(&swparams); 577 status = SDL_NAME(snd_pcm_sw_params_current)(pcm_handle, swparams); 578 if ( status < 0 ) { 579 SDL_SetError("Couldn't get software config: %s", SDL_NAME(snd_strerror)(status)); 580 ALSA_CloseAudio(this); 581 return(-1); 582 } 583 status = SDL_NAME(snd_pcm_sw_params_set_avail_min)(pcm_handle, swparams, spec->samples); 584 if ( status < 0 ) { 585 SDL_SetError("Couldn't set minimum available samples: %s", SDL_NAME(snd_strerror)(status)); 586 ALSA_CloseAudio(this); 587 return(-1); 588 } 589 status = SDL_NAME(snd_pcm_sw_params_set_start_threshold)(pcm_handle, swparams, 1); 590 if ( status < 0 ) { 591 SDL_SetError("Couldn't set start threshold: %s", SDL_NAME(snd_strerror)(status)); 592 ALSA_CloseAudio(this); 593 return(-1); 594 } 595 status = SDL_NAME(snd_pcm_sw_params)(pcm_handle, swparams); 596 if ( status < 0 ) { 597 SDL_SetError("Couldn't set software audio parameters: %s", SDL_NAME(snd_strerror)(status)); 598 ALSA_CloseAudio(this); 599 return(-1); 600 } 601 602 /* Calculate the final parameters for this audio specification */ 603 SDL_CalculateAudioSpec(spec); 604 605 /* Allocate mixing buffer */ 606 mixlen = spec->size; 607 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen); 608 if ( mixbuf == NULL ) { 609 ALSA_CloseAudio(this); 610 return(-1); 611 } 612 SDL_memset(mixbuf, spec->silence, spec->size); 613 614 /* Switch to blocking mode for playback */ 615 SDL_NAME(snd_pcm_nonblock)(pcm_handle, 0); 616 617 /* We're ready to rock and roll. :-) */ 618 return(0); 619} 620