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SDL-1.2.14
[sdl_omap.git] / src / audio / alsa / SDL_alsa_audio.c
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e14743d1 1/*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997-2009 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_current))(snd_pcm_t *pcm, snd_pcm_sw_params_t *swparams);
85static 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);
86static int (*SDL_NAME(snd_pcm_sw_params))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params);
87static int (*SDL_NAME(snd_pcm_nonblock))(snd_pcm_t *pcm, int nonblock);
88static int (*SDL_NAME(snd_pcm_wait))(snd_pcm_t *pcm, int timeout);
89#define snd_pcm_hw_params_sizeof SDL_NAME(snd_pcm_hw_params_sizeof)
90#define snd_pcm_sw_params_sizeof SDL_NAME(snd_pcm_sw_params_sizeof)
91
92/* cast funcs to char* first, to please GCC's strict aliasing rules. */
93static struct {
94 const char *name;
95 void **func;
96} alsa_functions[] = {
97 { "snd_pcm_open", (void**)(char*)&SDL_NAME(snd_pcm_open) },
98 { "snd_pcm_close", (void**)(char*)&SDL_NAME(snd_pcm_close) },
99 { "snd_pcm_writei", (void**)(char*)&SDL_NAME(snd_pcm_writei) },
100 { "snd_pcm_recover", (void**)(char*)&SDL_NAME(snd_pcm_recover) },
101 { "snd_pcm_prepare", (void**)(char*)&SDL_NAME(snd_pcm_prepare) },
102 { "snd_pcm_drain", (void**)(char*)&SDL_NAME(snd_pcm_drain) },
103 { "snd_strerror", (void**)(char*)&SDL_NAME(snd_strerror) },
104 { "snd_pcm_hw_params_sizeof", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_sizeof) },
105 { "snd_pcm_sw_params_sizeof", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_sizeof) },
106 { "snd_pcm_hw_params_copy", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_copy) },
107 { "snd_pcm_hw_params_any", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_any) },
108 { "snd_pcm_hw_params_set_access", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_access) },
109 { "snd_pcm_hw_params_set_format", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_format) },
110 { "snd_pcm_hw_params_set_channels", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_channels) },
111 { "snd_pcm_hw_params_get_channels", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_channels) },
112 { "snd_pcm_hw_params_set_rate_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_rate_near) },
113 { "snd_pcm_hw_params_set_period_size_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_period_size_near) },
114 { "snd_pcm_hw_params_get_period_size", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_period_size) },
115 { "snd_pcm_hw_params_set_periods_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_periods_near) },
116 { "snd_pcm_hw_params_get_periods", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_periods) },
117 { "snd_pcm_hw_params_set_buffer_size_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_buffer_size_near) },
118 { "snd_pcm_hw_params_get_buffer_size", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_buffer_size) },
119 { "snd_pcm_hw_params", (void**)(char*)&SDL_NAME(snd_pcm_hw_params) },
120 { "snd_pcm_sw_params_current", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_current) },
121 { "snd_pcm_sw_params_set_start_threshold", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_start_threshold) },
122 { "snd_pcm_sw_params", (void**)(char*)&SDL_NAME(snd_pcm_sw_params) },
123 { "snd_pcm_nonblock", (void**)(char*)&SDL_NAME(snd_pcm_nonblock) },
124 { "snd_pcm_wait", (void**)(char*)&SDL_NAME(snd_pcm_wait) },
125};
126
127static void UnloadALSALibrary(void) {
128 if (alsa_loaded) {
129 SDL_UnloadObject(alsa_handle);
130 alsa_handle = NULL;
131 alsa_loaded = 0;
132 }
133}
134
135static int LoadALSALibrary(void) {
136 int i, retval = -1;
137
138 alsa_handle = SDL_LoadObject(alsa_library);
139 if (alsa_handle) {
140 alsa_loaded = 1;
141 retval = 0;
142 for (i = 0; i < SDL_arraysize(alsa_functions); i++) {
143 *alsa_functions[i].func = SDL_LoadFunction(alsa_handle,alsa_functions[i].name);
144 if (!*alsa_functions[i].func) {
145 retval = -1;
146 UnloadALSALibrary();
147 break;
148 }
149 }
150 }
151 return retval;
152}
153
154#else
155
156static void UnloadALSALibrary(void) {
157 return;
158}
159
160static int LoadALSALibrary(void) {
161 return 0;
162}
163
164#endif /* SDL_AUDIO_DRIVER_ALSA_DYNAMIC */
165
166static const char *get_audio_device(int channels)
167{
168 const char *device;
169
170 device = SDL_getenv("AUDIODEV"); /* Is there a standard variable name? */
171 if ( device == NULL ) {
172 switch (channels) {
173 case 6:
174 device = "plug:surround51";
175 break;
176 case 4:
177 device = "plug:surround40";
178 break;
179 default:
180 device = "default";
181 break;
182 }
183 }
184 return device;
185}
186
187/* Audio driver bootstrap functions */
188
189static int Audio_Available(void)
190{
191 int available;
192 int status;
193 snd_pcm_t *handle;
194
195 available = 0;
196 if (LoadALSALibrary() < 0) {
197 return available;
198 }
199 status = SDL_NAME(snd_pcm_open)(&handle, get_audio_device(2), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
200 if ( status >= 0 ) {
201 available = 1;
202 SDL_NAME(snd_pcm_close)(handle);
203 }
204 UnloadALSALibrary();
205 return(available);
206}
207
208static void Audio_DeleteDevice(SDL_AudioDevice *device)
209{
210 SDL_free(device->hidden);
211 SDL_free(device);
212 UnloadALSALibrary();
213}
214
215static SDL_AudioDevice *Audio_CreateDevice(int devindex)
216{
217 SDL_AudioDevice *this;
218
219 /* Initialize all variables that we clean on shutdown */
220 LoadALSALibrary();
221 this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice));
222 if ( this ) {
223 SDL_memset(this, 0, (sizeof *this));
224 this->hidden = (struct SDL_PrivateAudioData *)
225 SDL_malloc((sizeof *this->hidden));
226 }
227 if ( (this == NULL) || (this->hidden == NULL) ) {
228 SDL_OutOfMemory();
229 if ( this ) {
230 SDL_free(this);
231 }
232 return(0);
233 }
234 SDL_memset(this->hidden, 0, (sizeof *this->hidden));
235
236 /* Set the function pointers */
237 this->OpenAudio = ALSA_OpenAudio;
238 this->WaitAudio = ALSA_WaitAudio;
239 this->PlayAudio = ALSA_PlayAudio;
240 this->GetAudioBuf = ALSA_GetAudioBuf;
241 this->CloseAudio = ALSA_CloseAudio;
242
243 this->free = Audio_DeleteDevice;
244
245 return this;
246}
247
248AudioBootStrap ALSA_bootstrap = {
249 DRIVER_NAME, "ALSA PCM audio",
250 Audio_Available, Audio_CreateDevice
251};
252
253/* This function waits until it is possible to write a full sound buffer */
254static void ALSA_WaitAudio(_THIS)
255{
256 /* We're in blocking mode, so there's nothing to do here */
257}
258
259
260/*
261 * http://bugzilla.libsdl.org/show_bug.cgi?id=110
262 * "For Linux ALSA, this is FL-FR-RL-RR-C-LFE
263 * and for Windows DirectX [and CoreAudio], this is FL-FR-C-LFE-RL-RR"
264 */
265#define SWIZ6(T) \
266 T *ptr = (T *) mixbuf; \
267 const Uint32 count = (this->spec.samples / 6); \
268 Uint32 i; \
269 for (i = 0; i < count; i++, ptr += 6) { \
270 T tmp; \
271 tmp = ptr[2]; ptr[2] = ptr[4]; ptr[4] = tmp; \
272 tmp = ptr[3]; ptr[3] = ptr[5]; ptr[5] = tmp; \
273 }
274
275static __inline__ void swizzle_alsa_channels_6_64bit(_THIS) { SWIZ6(Uint64); }
276static __inline__ void swizzle_alsa_channels_6_32bit(_THIS) { SWIZ6(Uint32); }
277static __inline__ void swizzle_alsa_channels_6_16bit(_THIS) { SWIZ6(Uint16); }
278static __inline__ void swizzle_alsa_channels_6_8bit(_THIS) { SWIZ6(Uint8); }
279
280#undef SWIZ6
281
282
283/*
284 * Called right before feeding this->mixbuf to the hardware. Swizzle channels
285 * from Windows/Mac order to the format alsalib will want.
286 */
287static __inline__ void swizzle_alsa_channels(_THIS)
288{
289 if (this->spec.channels == 6) {
290 const Uint16 fmtsize = (this->spec.format & 0xFF); /* bits/channel. */
291 if (fmtsize == 16)
292 swizzle_alsa_channels_6_16bit(this);
293 else if (fmtsize == 8)
294 swizzle_alsa_channels_6_8bit(this);
295 else if (fmtsize == 32)
296 swizzle_alsa_channels_6_32bit(this);
297 else if (fmtsize == 64)
298 swizzle_alsa_channels_6_64bit(this);
299 }
300
301 /* !!! FIXME: update this for 7.1 if needed, later. */
302}
303
304
305static void ALSA_PlayAudio(_THIS)
306{
307 int status;
308 snd_pcm_uframes_t frames_left;
309 const Uint8 *sample_buf = (const Uint8 *) mixbuf;
310 const int frame_size = (((int) (this->spec.format & 0xFF)) / 8) * this->spec.channels;
311
312 swizzle_alsa_channels(this);
313
314 frames_left = ((snd_pcm_uframes_t) this->spec.samples);
315
316 while ( frames_left > 0 && this->enabled ) {
317 /* This works, but needs more testing before going live */
318 /*SDL_NAME(snd_pcm_wait)(pcm_handle, -1);*/
319
320 status = SDL_NAME(snd_pcm_writei)(pcm_handle, sample_buf, frames_left);
321 if ( status < 0 ) {
322 if ( status == -EAGAIN ) {
323 /* Apparently snd_pcm_recover() doesn't handle this case - does it assume snd_pcm_wait() above? */
324 SDL_Delay(1);
325 continue;
326 }
327 status = SDL_NAME(snd_pcm_recover)(pcm_handle, status, 0);
328 if ( status < 0 ) {
329 /* Hmm, not much we can do - abort */
330 fprintf(stderr, "ALSA write failed (unrecoverable): %s\n", SDL_NAME(snd_strerror)(status));
331 this->enabled = 0;
332 return;
333 }
334 continue;
335 }
336 sample_buf += status * frame_size;
337 frames_left -= status;
338 }
339}
340
341static Uint8 *ALSA_GetAudioBuf(_THIS)
342{
343 return(mixbuf);
344}
345
346static void ALSA_CloseAudio(_THIS)
347{
348 if ( mixbuf != NULL ) {
349 SDL_FreeAudioMem(mixbuf);
350 mixbuf = NULL;
351 }
352 if ( pcm_handle ) {
353 SDL_NAME(snd_pcm_drain)(pcm_handle);
354 SDL_NAME(snd_pcm_close)(pcm_handle);
355 pcm_handle = NULL;
356 }
357}
358
359static int ALSA_finalize_hardware(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *hwparams, int override)
360{
361 int status;
362 snd_pcm_uframes_t bufsize;
363
364 /* "set" the hardware with the desired parameters */
365 status = SDL_NAME(snd_pcm_hw_params)(pcm_handle, hwparams);
366 if ( status < 0 ) {
367 return(-1);
368 }
369
370 /* Get samples for the actual buffer size */
371 status = SDL_NAME(snd_pcm_hw_params_get_buffer_size)(hwparams, &bufsize);
372 if ( status < 0 ) {
373 return(-1);
374 }
375 if ( !override && bufsize != spec->samples * 2 ) {
376 return(-1);
377 }
378
379 /* FIXME: Is this safe to do? */
380 spec->samples = bufsize / 2;
381
382 /* This is useful for debugging */
383 if ( getenv("SDL_AUDIO_ALSA_DEBUG") ) {
384 snd_pcm_uframes_t persize = 0;
385 unsigned int periods = 0;
386
387 SDL_NAME(snd_pcm_hw_params_get_period_size)(hwparams, &persize, NULL);
388 SDL_NAME(snd_pcm_hw_params_get_periods)(hwparams, &periods, NULL);
389
390 fprintf(stderr, "ALSA: period size = %ld, periods = %u, buffer size = %lu\n", persize, periods, bufsize);
391 }
392 return(0);
393}
394
395static int ALSA_set_period_size(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *params, int override)
396{
397 const char *env;
398 int status;
399 snd_pcm_hw_params_t *hwparams;
400 snd_pcm_uframes_t frames;
401 unsigned int periods;
402
403 /* Copy the hardware parameters for this setup */
404 snd_pcm_hw_params_alloca(&hwparams);
405 SDL_NAME(snd_pcm_hw_params_copy)(hwparams, params);
406
407 if ( !override ) {
408 env = getenv("SDL_AUDIO_ALSA_SET_PERIOD_SIZE");
409 if ( env ) {
410 override = SDL_atoi(env);
411 if ( override == 0 ) {
412 return(-1);
413 }
414 }
415 }
416
417 frames = spec->samples;
418 status = SDL_NAME(snd_pcm_hw_params_set_period_size_near)(pcm_handle, hwparams, &frames, NULL);
419 if ( status < 0 ) {
420 return(-1);
421 }
422
423 periods = 2;
424 status = SDL_NAME(snd_pcm_hw_params_set_periods_near)(pcm_handle, hwparams, &periods, NULL);
425 if ( status < 0 ) {
426 return(-1);
427 }
428
429 return ALSA_finalize_hardware(this, spec, hwparams, override);
430}
431
432static int ALSA_set_buffer_size(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *params, int override)
433{
434 const char *env;
435 int status;
436 snd_pcm_hw_params_t *hwparams;
437 snd_pcm_uframes_t frames;
438
439 /* Copy the hardware parameters for this setup */
440 snd_pcm_hw_params_alloca(&hwparams);
441 SDL_NAME(snd_pcm_hw_params_copy)(hwparams, params);
442
443 if ( !override ) {
444 env = getenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE");
445 if ( env ) {
446 override = SDL_atoi(env);
447 if ( override == 0 ) {
448 return(-1);
449 }
450 }
451 }
452
453 frames = spec->samples * 2;
454 status = SDL_NAME(snd_pcm_hw_params_set_buffer_size_near)(pcm_handle, hwparams, &frames);
455 if ( status < 0 ) {
456 return(-1);
457 }
458
459 return ALSA_finalize_hardware(this, spec, hwparams, override);
460}
461
462static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
463{
464 int status;
465 snd_pcm_hw_params_t *hwparams;
466 snd_pcm_sw_params_t *swparams;
467 snd_pcm_format_t format;
468 unsigned int rate;
469 unsigned int channels;
470 Uint16 test_format;
471
472 /* Open the audio device */
473 /* Name of device should depend on # channels in spec */
474 status = SDL_NAME(snd_pcm_open)(&pcm_handle, get_audio_device(spec->channels), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
475
476 if ( status < 0 ) {
477 SDL_SetError("Couldn't open audio device: %s", SDL_NAME(snd_strerror)(status));
478 return(-1);
479 }
480
481 /* Figure out what the hardware is capable of */
482 snd_pcm_hw_params_alloca(&hwparams);
483 status = SDL_NAME(snd_pcm_hw_params_any)(pcm_handle, hwparams);
484 if ( status < 0 ) {
485 SDL_SetError("Couldn't get hardware config: %s", SDL_NAME(snd_strerror)(status));
486 ALSA_CloseAudio(this);
487 return(-1);
488 }
489
490 /* SDL only uses interleaved sample output */
491 status = SDL_NAME(snd_pcm_hw_params_set_access)(pcm_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED);
492 if ( status < 0 ) {
493 SDL_SetError("Couldn't set interleaved access: %s", SDL_NAME(snd_strerror)(status));
494 ALSA_CloseAudio(this);
495 return(-1);
496 }
497
498 /* Try for a closest match on audio format */
499 status = -1;
500 for ( test_format = SDL_FirstAudioFormat(spec->format);
501 test_format && (status < 0); ) {
502 switch ( test_format ) {
503 case AUDIO_U8:
504 format = SND_PCM_FORMAT_U8;
505 break;
506 case AUDIO_S8:
507 format = SND_PCM_FORMAT_S8;
508 break;
509 case AUDIO_S16LSB:
510 format = SND_PCM_FORMAT_S16_LE;
511 break;
512 case AUDIO_S16MSB:
513 format = SND_PCM_FORMAT_S16_BE;
514 break;
515 case AUDIO_U16LSB:
516 format = SND_PCM_FORMAT_U16_LE;
517 break;
518 case AUDIO_U16MSB:
519 format = SND_PCM_FORMAT_U16_BE;
520 break;
521 default:
522 format = 0;
523 break;
524 }
525 if ( format != 0 ) {
526 status = SDL_NAME(snd_pcm_hw_params_set_format)(pcm_handle, hwparams, format);
527 }
528 if ( status < 0 ) {
529 test_format = SDL_NextAudioFormat();
530 }
531 }
532 if ( status < 0 ) {
533 SDL_SetError("Couldn't find any hardware audio formats");
534 ALSA_CloseAudio(this);
535 return(-1);
536 }
537 spec->format = test_format;
538
539 /* Set the number of channels */
540 status = SDL_NAME(snd_pcm_hw_params_set_channels)(pcm_handle, hwparams, spec->channels);
541 channels = spec->channels;
542 if ( status < 0 ) {
543 status = SDL_NAME(snd_pcm_hw_params_get_channels)(hwparams, &channels);
544 if ( status < 0 ) {
545 SDL_SetError("Couldn't set audio channels");
546 ALSA_CloseAudio(this);
547 return(-1);
548 }
549 spec->channels = channels;
550 }
551
552 /* Set the audio rate */
553 rate = spec->freq;
554
555 status = SDL_NAME(snd_pcm_hw_params_set_rate_near)(pcm_handle, hwparams, &rate, NULL);
556 if ( status < 0 ) {
557 SDL_SetError("Couldn't set audio frequency: %s", SDL_NAME(snd_strerror)(status));
558 ALSA_CloseAudio(this);
559 return(-1);
560 }
561 spec->freq = rate;
562
563 /* Set the buffer size, in samples */
564 if ( ALSA_set_period_size(this, spec, hwparams, 0) < 0 &&
565 ALSA_set_buffer_size(this, spec, hwparams, 0) < 0 ) {
566 /* Failed to set desired buffer size, do the best you can... */
567 if ( ALSA_set_period_size(this, spec, hwparams, 1) < 0 ) {
568 SDL_SetError("Couldn't set hardware audio parameters: %s", SDL_NAME(snd_strerror)(status));
569 ALSA_CloseAudio(this);
570 return(-1);
571 }
572 }
573
574 /* Set the software parameters */
575 snd_pcm_sw_params_alloca(&swparams);
576 status = SDL_NAME(snd_pcm_sw_params_current)(pcm_handle, swparams);
577 if ( status < 0 ) {
578 SDL_SetError("Couldn't get software config: %s", SDL_NAME(snd_strerror)(status));
579 ALSA_CloseAudio(this);
580 return(-1);
581 }
582 status = SDL_NAME(snd_pcm_sw_params_set_start_threshold)(pcm_handle, swparams, 1);
583 if ( status < 0 ) {
584 SDL_SetError("Couldn't set start threshold: %s", SDL_NAME(snd_strerror)(status));
585 ALSA_CloseAudio(this);
586 return(-1);
587 }
588 status = SDL_NAME(snd_pcm_sw_params)(pcm_handle, swparams);
589 if ( status < 0 ) {
590 SDL_SetError("Couldn't set software audio parameters: %s", SDL_NAME(snd_strerror)(status));
591 ALSA_CloseAudio(this);
592 return(-1);
593 }
594
595 /* Calculate the final parameters for this audio specification */
596 SDL_CalculateAudioSpec(spec);
597
598 /* Allocate mixing buffer */
599 mixlen = spec->size;
600 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
601 if ( mixbuf == NULL ) {
602 ALSA_CloseAudio(this);
603 return(-1);
604 }
605 SDL_memset(mixbuf, spec->silence, spec->size);
606
607 /* Switch to blocking mode for playback */
608 SDL_NAME(snd_pcm_nonblock)(pcm_handle, 0);
609
610 /* We're ready to rock and roll. :-) */
611 return(0);
612}
SDL with some OMAP hardware support