src/audio/dma/SDL_dmaaudio.c
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FUNCTIONS
This source file includes following functions.
- Audio_Available
- Audio_DeleteDevice
- Audio_CreateDevice
- DMA_WaitAudio
- DMA_PlayAudio
- DMA_GetAudioBuf
- DMA_CloseAudio
- DMA_ReopenAudio
- DMA_OpenAudio
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997, 1998, 1999, 2000, 2001 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@devolution.com
21 */
22
23 #ifdef SAVE_RCSID
24 static char rcsid =
25 "@(#) $Id: SDL_dmaaudio.c,v 1.1.2.3 2001/03/21 17:19:56 hercules Exp $";
26 #endif
27
28 /* Allow access to a raw mixing buffer */
29
30 #include <stdlib.h>
31 #include <stdio.h>
32 #include <string.h>
33 #include <errno.h>
34 #include <unistd.h>
35 #include <fcntl.h>
36 #include <signal.h>
37 #include <sys/types.h>
38 #include <sys/time.h>
39 #include <sys/ioctl.h>
40 #include <sys/stat.h>
41 #include <sys/mman.h>
42 #ifdef linux
43 #include <linux/soundcard.h>
44 #endif
45 #ifdef __bsdi__
46 #include <sys/soundcard.h>
47 #endif
48 #ifdef __FreeBSD__
49 #include <machine/soundcard.h>
50 #endif
51 #ifdef __USLC__
52 #include <sys/soundcard.h>
53 #endif
54
55 #ifndef MAP_FAILED
56 #define MAP_FAILED ((Uint8 *)-1)
57 #endif
58
59 #include "SDL_audio.h"
60 #include "SDL_error.h"
61 #include "SDL_audiomem.h"
62 #include "SDL_audio_c.h"
63 #include "SDL_timer.h"
64 #include "SDL_audiodev_c.h"
65 #include "SDL_dmaaudio.h"
66
67 /* The tag name used by DMA audio */
68 #define DMA_DRIVER_NAME "dma"
69
70 /* Open the audio device for playback, and don't block if busy */
71 #define OPEN_FLAGS (O_RDWR|O_NONBLOCK)
72
73 /* Audio driver functions */
74 static int DMA_OpenAudio(_THIS, SDL_AudioSpec *spec);
75 static void DMA_WaitAudio(_THIS);
76 static void DMA_PlayAudio(_THIS);
77 static Uint8 *DMA_GetAudioBuf(_THIS);
78 static void DMA_CloseAudio(_THIS);
79
80 /* Audio driver bootstrap functions */
81
82 static int Audio_Available(void)
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83 {
84 int available;
85 int fd;
86
87 available = 0;
88
89 fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);
90 if ( fd >= 0 ) {
91 int caps;
92 struct audio_buf_info info;
93
94 if ( (ioctl(fd, SNDCTL_DSP_GETCAPS, &caps) == 0) &&
95 (caps & DSP_CAP_TRIGGER) && (caps & DSP_CAP_MMAP) &&
96 (ioctl(fd, SNDCTL_DSP_GETOSPACE, &info) == 0) ) {
97 available = 1;
98 }
99 close(fd);
100 }
101 return(available);
102 }
103
104 static void Audio_DeleteDevice(SDL_AudioDevice *device)
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105 {
106 free(device->hidden);
107 free(device);
108 }
109
110 static SDL_AudioDevice *Audio_CreateDevice(int devindex)
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111 {
112 SDL_AudioDevice *this;
113
114 /* Initialize all variables that we clean on shutdown */
115 this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
116 if ( this ) {
117 memset(this, 0, (sizeof *this));
118 this->hidden = (struct SDL_PrivateAudioData *)
119 malloc((sizeof *this->hidden));
120 }
121 if ( (this == NULL) || (this->hidden == NULL) ) {
122 SDL_OutOfMemory();
123 if ( this ) {
124 free(this);
125 }
126 return(0);
127 }
128 memset(this->hidden, 0, (sizeof *this->hidden));
129 audio_fd = -1;
130
131 /* Set the function pointers */
132 this->OpenAudio = DMA_OpenAudio;
133 this->WaitAudio = DMA_WaitAudio;
134 this->PlayAudio = DMA_PlayAudio;
135 this->GetAudioBuf = DMA_GetAudioBuf;
136 this->CloseAudio = DMA_CloseAudio;
137
138 this->free = Audio_DeleteDevice;
139
140 return this;
141 }
142
143 AudioBootStrap DMA_bootstrap = {
144 DMA_DRIVER_NAME, "OSS /dev/dsp DMA audio",
145 Audio_Available, Audio_CreateDevice
146 };
147
148 /* This function waits until it is possible to write a full sound buffer */
149 static void DMA_WaitAudio(_THIS)
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150 {
151 fd_set fdset;
152
153 /* Check to see if the thread-parent process is still alive */
154 { static int cnt = 0;
155 /* Note that this only works with thread implementations
156 that use a different process id for each thread.
157 */
158 if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
159 if ( kill(parent, 0) < 0 ) {
160 this->enabled = 0;
161 }
162 }
163 }
164
165 /* See if we need to use timed audio synchronization */
166 if ( frame_ticks ) {
167 /* Use timer for general audio synchronization */
168 Sint32 ticks;
169
170 ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;
171 if ( ticks > 0 ) {
172 SDL_Delay(ticks);
173 }
174 } else {
175 /* Use select() for audio synchronization */
176 struct timeval timeout;
177 FD_ZERO(&fdset);
178 FD_SET(audio_fd, &fdset);
179 timeout.tv_sec = 10;
180 timeout.tv_usec = 0;
181 #ifdef DEBUG_AUDIO
182 fprintf(stderr, "Waiting for audio to get ready\n");
183 #endif
184 if ( select(audio_fd+1, NULL, &fdset, NULL, &timeout) <= 0 ) {
185 const char *message =
186 #ifdef AUDIO_OSPACE_HACK
187 "Audio timeout - buggy audio driver? (trying ospace)";
188 #else
189 "Audio timeout - buggy audio driver? (disabled)";
190 #endif
191 /* In general we should never print to the screen,
192 but in this case we have no other way of letting
193 the user know what happened.
194 */
195 fprintf(stderr, "SDL: %s\n", message);
196 #ifdef AUDIO_OSPACE_HACK
197 /* We may be able to use GET_OSPACE trick */
198 frame_ticks = (float)(this->spec->samples*1000) /
199 this->spec->freq;
200 next_frame = SDL_GetTicks()+frame_ticks;
201 #else
202 this->enabled = 0;
203 /* Don't try to close - may hang */
204 audio_fd = -1;
205 #ifdef DEBUG_AUDIO
206 fprintf(stderr, "Done disabling audio\n");
207 #endif
208 #endif /* AUDIO_OSPACE_HACK */
209 }
210 #ifdef DEBUG_AUDIO
211 fprintf(stderr, "Ready!\n");
212 #endif
213 }
214 }
215
216 static void DMA_PlayAudio(_THIS)
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217 {
218 /* If timer synchronization is enabled, set the next write frame */
219 if ( frame_ticks ) {
220 next_frame += frame_ticks;
221 }
222 return;
223 }
224
225 static Uint8 *DMA_GetAudioBuf(_THIS)
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226 {
227 count_info info;
228 int playing;
229 int filling;
230
231 /* Get number of blocks, looping if we're not using select() */
232 do {
233 if ( ioctl(audio_fd, SNDCTL_DSP_GETOPTR, &info) < 0 ) {
234 /* Uh oh... */
235 this->enabled = 0;
236 return(NULL);
237 }
238 } while ( frame_ticks && (info.blocks < 1) );
239 #ifdef DEBUG_AUDIO
240 if ( info.blocks > 1 ) {
241 printf("Warning: audio underflow (%d frags)\n", info.blocks-1);
242 }
243 #endif
244 playing = info.ptr / this->spec.size;
245 filling = (playing + 1)%num_buffers;
246 return (dma_buf + (filling * this->spec.size));
247 }
248
249 static void DMA_CloseAudio(_THIS)
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250 {
251 if ( dma_buf != NULL ) {
252 munmap(dma_buf, dma_len);
253 dma_buf = NULL;
254 }
255 if ( audio_fd >= 0 ) {
256 close(audio_fd);
257 audio_fd = -1;
258 }
259 }
260
261 static int DMA_ReopenAudio(_THIS, const char *audiodev, int format, int stereo,
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262 SDL_AudioSpec *spec)
263 {
264 int frag_spec;
265 int value;
266
267 /* Close and then reopen the audio device */
268 close(audio_fd);
269 audio_fd = open(audiodev, O_RDWR, 0);
270 if ( audio_fd < 0 ) {
271 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
272 return(-1);
273 }
274 ioctl(audio_fd, SNDCTL_DSP_RESET, 0);
275
276 /* Calculate the final parameters for this audio specification */
277 SDL_CalculateAudioSpec(spec);
278
279 /* Determine the power of two of the fragment size */
280 for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
281 if ( (0x01<<frag_spec) != spec->size ) {
282 SDL_SetError("Fragment size must be a power of two");
283 return(-1);
284 }
285
286 /* Set the audio buffering parameters */
287 if ( ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0 ) {
288 SDL_SetError("Couldn't set audio fragment spec");
289 return(-1);
290 }
291
292 /* Set the audio format */
293 value = format;
294 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
295 (value != format) ) {
296 SDL_SetError("Couldn't set audio format");
297 return(-1);
298 }
299
300 /* Set mono or stereo audio */
301 value = (spec->channels > 1);
302 if ( (ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo) < 0) ||
303 (value != stereo) ) {
304 SDL_SetError("Couldn't set audio channels");
305 return(-1);
306 }
307
308 /* Set the DSP frequency */
309 value = spec->freq;
310 if ( ioctl(audio_fd, SOUND_PCM_WRITE_RATE, &value) < 0 ) {
311 SDL_SetError("Couldn't set audio frequency");
312 return(-1);
313 }
314 spec->freq = value;
315
316 /* We successfully re-opened the audio */
317 return(0);
318 }
319
320 static int DMA_OpenAudio(_THIS, SDL_AudioSpec *spec)
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321 {
322 char audiodev[1024];
323 int format;
324 int stereo;
325 int value;
326 Uint16 test_format;
327 struct audio_buf_info info;
328
329 /* Reset the timer synchronization flag */
330 frame_ticks = 0.0;
331
332 /* Open the audio device */
333 audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0);
334 if ( audio_fd < 0 ) {
335 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
336 return(-1);
337 }
338 dma_buf = NULL;
339 ioctl(audio_fd, SNDCTL_DSP_RESET, 0);
340
341 /* Get a list of supported hardware formats */
342 if ( ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0 ) {
343 SDL_SetError("Couldn't get audio format list");
344 return(-1);
345 }
346
347 /* Try for a closest match on audio format */
348 format = 0;
349 for ( test_format = SDL_FirstAudioFormat(spec->format);
350 ! format && test_format; ) {
351 #ifdef DEBUG_AUDIO
352 fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
353 #endif
354 switch ( test_format ) {
355 case AUDIO_U8:
356 if ( value & AFMT_U8 ) {
357 format = AFMT_U8;
358 }
359 break;
360 case AUDIO_S8:
361 if ( value & AFMT_S8 ) {
362 format = AFMT_S8;
363 }
364 break;
365 case AUDIO_S16LSB:
366 if ( value & AFMT_S16_LE ) {
367 format = AFMT_S16_LE;
368 }
369 break;
370 case AUDIO_S16MSB:
371 if ( value & AFMT_S16_BE ) {
372 format = AFMT_S16_BE;
373 }
374 break;
375 case AUDIO_U16LSB:
376 if ( value & AFMT_U16_LE ) {
377 format = AFMT_U16_LE;
378 }
379 break;
380 case AUDIO_U16MSB:
381 if ( value & AFMT_U16_BE ) {
382 format = AFMT_U16_BE;
383 }
384 break;
385 default:
386 break;
387 }
388 if ( ! format ) {
389 test_format = SDL_NextAudioFormat();
390 }
391 }
392 if ( format == 0 ) {
393 SDL_SetError("Couldn't find any hardware audio formats");
394 return(-1);
395 }
396 spec->format = test_format;
397
398 /* Set the audio format */
399 value = format;
400 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
401 (value != format) ) {
402 SDL_SetError("Couldn't set audio format");
403 return(-1);
404 }
405
406 /* Set mono or stereo audio (currently only two channels supported) */
407 stereo = (spec->channels > 1);
408 ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo);
409 if ( stereo ) {
410 spec->channels = 2;
411 } else {
412 spec->channels = 1;
413 }
414
415 /* Because some drivers don't allow setting the buffer size
416 after setting the format, we must re-open the audio device
417 once we know what format and channels are supported
418 */
419 if ( DMA_ReopenAudio(this, audiodev, format, stereo, spec) < 0 ) {
420 /* Error is set by DMA_ReopenAudio() */
421 return(-1);
422 }
423
424 /* Memory map the audio buffer */
425 if ( ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info) < 0 ) {
426 SDL_SetError("Couldn't get OSPACE parameters");
427 return(-1);
428 }
429 spec->size = info.fragsize;
430 spec->samples = spec->size / ((spec->format & 0xFF) / 8);
431 spec->samples /= spec->channels;
432 num_buffers = info.fragstotal;
433 dma_len = num_buffers*spec->size;
434 dma_buf = (Uint8 *)mmap(NULL, dma_len, PROT_WRITE, MAP_SHARED,
435 audio_fd, 0);
436 if ( dma_buf == MAP_FAILED ) {
437 SDL_SetError("DMA memory map failed");
438 dma_buf = NULL;
439 return(-1);
440 }
441 memset(dma_buf, spec->silence, dma_len);
442
443 /* Check to see if we need to use select() workaround */
444 { char *workaround;
445 workaround = getenv("SDL_DSP_NOSELECT");
446 if ( workaround ) {
447 frame_ticks = (float)(spec->samples*1000)/spec->freq;
448 next_frame = SDL_GetTicks()+frame_ticks;
449 }
450 }
451
452 /* Trigger audio playback */
453 value = 0;
454 ioctl(audio_fd, SNDCTL_DSP_SETTRIGGER, &value);
455 value = PCM_ENABLE_OUTPUT;
456 if ( ioctl(audio_fd, SNDCTL_DSP_SETTRIGGER, &value) < 0 ) {
457 SDL_SetError("Couldn't trigger audio output");
458 return(-1);
459 }
460
461 /* Get the parent process id (we're the parent of the audio thread) */
462 parent = getpid();
463
464 /* We're ready to rock and roll. :-) */
465 return(0);
466 }