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comparison src/audio/dsp/SDL_dspaudio.c @ 0:74212992fb08

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Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
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children cf2af46e9e2a
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-1:000000000000 0:74212992fb08
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 "@(#) $Id$";
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/time.h>
38 #include <sys/ioctl.h>
39 #include <sys/stat.h>
40 #ifdef linux
41 #include <linux/soundcard.h>
42 #endif
43 #ifdef __bsdi__
44 #include <sys/soundcard.h>
45 #endif
46 #ifdef __FreeBSD__
47 #include <machine/soundcard.h>
48 #endif
49 #ifdef __USLC__
50 #include <sys/soundcard.h>
51 #endif
52
53 #include "SDL_audio.h"
54 #include "SDL_error.h"
55 #include "SDL_audiomem.h"
56 #include "SDL_audio_c.h"
57 #include "SDL_timer.h"
58 #include "SDL_audiodev_c.h"
59 #include "SDL_dspaudio.h"
60
61 /* The tag name used by DSP audio */
62 #define DSP_DRIVER_NAME "dsp"
63
64 /* Open the audio device for playback, and don't block if busy */
65 /*#define USE_BLOCKING_WRITES*/
66 #ifdef USE_BLOCKING_WRITES
67 #define OPEN_FLAGS O_WRONLY
68 #else
69 #define OPEN_FLAGS (O_WRONLY|O_NONBLOCK)
70 #endif
71
72 /* Audio driver functions */
73 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec);
74 static void DSP_WaitAudio(_THIS);
75 static void DSP_PlayAudio(_THIS);
76 static Uint8 *DSP_GetAudioBuf(_THIS);
77 static void DSP_CloseAudio(_THIS);
78
79 /* Audio driver bootstrap functions */
80
81 static int Audio_Available(void)
82 {
83 int fd;
84 int available;
85
86 available = 0;
87 fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);
88 if ( fd >= 0 ) {
89 available = 1;
90 close(fd);
91 }
92 return(available);
93 }
94
95 static void Audio_DeleteDevice(SDL_AudioDevice *device)
96 {
97 free(device->hidden);
98 free(device);
99 }
100
101 static SDL_AudioDevice *Audio_CreateDevice(int devindex)
102 {
103 SDL_AudioDevice *this;
104
105 /* Initialize all variables that we clean on shutdown */
106 this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
107 if ( this ) {
108 memset(this, 0, (sizeof *this));
109 this->hidden = (struct SDL_PrivateAudioData *)
110 malloc((sizeof *this->hidden));
111 }
112 if ( (this == NULL) || (this->hidden == NULL) ) {
113 SDL_OutOfMemory();
114 if ( this ) {
115 free(this);
116 }
117 return(0);
118 }
119 memset(this->hidden, 0, (sizeof *this->hidden));
120 audio_fd = -1;
121
122 /* Set the function pointers */
123 this->OpenAudio = DSP_OpenAudio;
124 this->WaitAudio = DSP_WaitAudio;
125 this->PlayAudio = DSP_PlayAudio;
126 this->GetAudioBuf = DSP_GetAudioBuf;
127 this->CloseAudio = DSP_CloseAudio;
128
129 this->free = Audio_DeleteDevice;
130
131 return this;
132 }
133
134 AudioBootStrap DSP_bootstrap = {
135 DSP_DRIVER_NAME, "OSS /dev/dsp standard audio",
136 Audio_Available, Audio_CreateDevice
137 };
138
139 /* This function waits until it is possible to write a full sound buffer */
140 static void DSP_WaitAudio(_THIS)
141 {
142 #ifndef USE_BLOCKING_WRITES /* Not necessary because of blocking writes */
143 fd_set fdset;
144
145 /* Check to see if the thread-parent process is still alive */
146 { static int cnt = 0;
147 /* Note that this only works with thread implementations
148 that use a different process id for each thread.
149 */
150 if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
151 if ( kill(parent, 0) < 0 ) {
152 this->enabled = 0;
153 }
154 }
155 }
156
157 /* See if we need to use timed audio synchronization */
158 if ( frame_ticks ) {
159 /* Use timer for general audio synchronization */
160 Sint32 ticks;
161
162 ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;
163 if ( ticks > 0 ) {
164 SDL_Delay(ticks);
165 }
166 } else {
167 /* Use select() for audio synchronization */
168 struct timeval timeout;
169 FD_ZERO(&fdset);
170 FD_SET(audio_fd, &fdset);
171 timeout.tv_sec = 10;
172 timeout.tv_usec = 0;
173 #ifdef DEBUG_AUDIO
174 fprintf(stderr, "Waiting for audio to get ready\n");
175 #endif
176 if ( select(audio_fd+1, NULL, &fdset, NULL, &timeout) <= 0 ) {
177 const char *message =
178 "Audio timeout - buggy audio driver? (disabled)";
179 /* In general we should never print to the screen,
180 but in this case we have no other way of letting
181 the user know what happened.
182 */
183 fprintf(stderr, "SDL: %s\n", message);
184 this->enabled = 0;
185 /* Don't try to close - may hang */
186 audio_fd = -1;
187 #ifdef DEBUG_AUDIO
188 fprintf(stderr, "Done disabling audio\n");
189 #endif
190 }
191 #ifdef DEBUG_AUDIO
192 fprintf(stderr, "Ready!\n");
193 #endif
194 }
195 #endif /* !USE_BLOCKING_WRITES */
196 }
197
198 static void DSP_PlayAudio(_THIS)
199 {
200 int written;
201
202 /* Write the audio data, checking for EAGAIN on broken audio drivers */
203 do {
204 written = write(audio_fd, mixbuf, mixlen);
205 if ( (written < 0) && ((errno == 0) || (errno == EAGAIN)) ) {
206 SDL_Delay(1); /* Let a little CPU time go by */
207 }
208 } while ( (written < 0) &&
209 ((errno == 0) || (errno == EAGAIN) || (errno == EINTR)) );
210
211 /* If timer synchronization is enabled, set the next write frame */
212 if ( frame_ticks ) {
213 next_frame += frame_ticks;
214 }
215
216 /* If we couldn't write, assume fatal error for now */
217 if ( written < 0 ) {
218 this->enabled = 0;
219 }
220 #ifdef DEBUG_AUDIO
221 fprintf(stderr, "Wrote %d bytes of audio data\n", written);
222 #endif
223 }
224
225 static Uint8 *DSP_GetAudioBuf(_THIS)
226 {
227 return(mixbuf);
228 }
229
230 static void DSP_CloseAudio(_THIS)
231 {
232 if ( mixbuf != NULL ) {
233 SDL_FreeAudioMem(mixbuf);
234 mixbuf = NULL;
235 }
236 if ( audio_fd >= 0 ) {
237 close(audio_fd);
238 audio_fd = -1;
239 }
240 }
241
242 static int DSP_ReopenAudio(_THIS, const char *audiodev, int format,
243 SDL_AudioSpec *spec)
244 {
245 int frag_spec;
246 int value;
247
248 /* Close and then reopen the audio device */
249 close(audio_fd);
250 audio_fd = open(audiodev, O_WRONLY, 0);
251 if ( audio_fd < 0 ) {
252 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
253 return(-1);
254 }
255
256 /* Calculate the final parameters for this audio specification */
257 SDL_CalculateAudioSpec(spec);
258
259 /* Determine the power of two of the fragment size */
260 for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
261 if ( (0x01<<frag_spec) != spec->size ) {
262 SDL_SetError("Fragment size must be a power of two");
263 return(-1);
264 }
265 frag_spec |= 0x00020000; /* two fragments, for low latency */
266
267 /* Set the audio buffering parameters */
268 #ifdef DEBUG_AUDIO
269 fprintf(stderr, "Requesting %d fragments of size %d\n",
270 (frag_spec >> 16), 1<<(frag_spec&0xFFFF));
271 #endif
272 if ( ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0 ) {
273 fprintf(stderr, "Warning: Couldn't set audio fragment size\n");
274 }
275 #ifdef DEBUG_AUDIO
276 { audio_buf_info info;
277 ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info);
278 fprintf(stderr, "fragments = %d\n", info.fragments);
279 fprintf(stderr, "fragstotal = %d\n", info.fragstotal);
280 fprintf(stderr, "fragsize = %d\n", info.fragsize);
281 fprintf(stderr, "bytes = %d\n", info.bytes);
282 }
283 #endif
284
285 /* Set the audio format */
286 value = format;
287 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
288 (value != format) ) {
289 SDL_SetError("Couldn't set audio format");
290 return(-1);
291 }
292
293 /* Set the number of channels of output */
294 value = spec->channels;
295 #ifdef SNDCTL_DSP_CHANNELS
296 if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) {
297 #endif
298 value = (spec->channels > 1);
299 ioctl(audio_fd, SNDCTL_DSP_STEREO, &value);
300 value = (value ? 2 : 1);
301 #ifdef SNDCTL_DSP_CHANNELS
302 }
303 #endif
304 if ( value != spec->channels ) {
305 SDL_SetError("Couldn't set audio channels");
306 return(-1);
307 }
308
309 /* Set the DSP frequency */
310 value = spec->freq;
311 if ( ioctl(audio_fd, SOUND_PCM_WRITE_RATE, &value) < 0 ) {
312 SDL_SetError("Couldn't set audio frequency");
313 return(-1);
314 }
315 spec->freq = value;
316
317 /* We successfully re-opened the audio */
318 return(0);
319 }
320
321 static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec)
322 {
323 char audiodev[1024];
324 int format;
325 int value;
326 Uint16 test_format;
327
328 /* Reset the timer synchronization flag */
329 frame_ticks = 0.0;
330
331 /* Open the audio device */
332 audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0);
333 if ( audio_fd < 0 ) {
334 SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
335 return(-1);
336 }
337 mixbuf = NULL;
338
339 /* Get a list of supported hardware formats */
340 if ( ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0 ) {
341 SDL_SetError("Couldn't get audio format list");
342 return(-1);
343 }
344
345 /* Try for a closest match on audio format */
346 format = 0;
347 for ( test_format = SDL_FirstAudioFormat(spec->format);
348 ! format && test_format; ) {
349 #ifdef DEBUG_AUDIO
350 fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
351 #endif
352 switch ( test_format ) {
353 case AUDIO_U8:
354 if ( value & AFMT_U8 ) {
355 format = AFMT_U8;
356 }
357 break;
358 case AUDIO_S8:
359 if ( value & AFMT_S8 ) {
360 format = AFMT_S8;
361 }
362 break;
363 case AUDIO_S16LSB:
364 if ( value & AFMT_S16_LE ) {
365 format = AFMT_S16_LE;
366 }
367 break;
368 case AUDIO_S16MSB:
369 if ( value & AFMT_S16_BE ) {
370 format = AFMT_S16_BE;
371 }
372 break;
373 case AUDIO_U16LSB:
374 if ( value & AFMT_U16_LE ) {
375 format = AFMT_U16_LE;
376 }
377 break;
378 case AUDIO_U16MSB:
379 if ( value & AFMT_U16_BE ) {
380 format = AFMT_U16_BE;
381 }
382 break;
383 default:
384 break;
385 }
386 if ( ! format ) {
387 test_format = SDL_NextAudioFormat();
388 }
389 }
390 if ( format == 0 ) {
391 SDL_SetError("Couldn't find any hardware audio formats");
392 return(-1);
393 }
394 spec->format = test_format;
395
396 /* Set the audio format */
397 value = format;
398 if ( (ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) ||
399 (value != format) ) {
400 SDL_SetError("Couldn't set audio format");
401 return(-1);
402 }
403
404 /* Set the number of channels of output */
405 value = spec->channels;
406 #ifdef SNDCTL_DSP_CHANNELS
407 if ( ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0 ) {
408 #endif
409 value = (spec->channels > 1);
410 ioctl(audio_fd, SNDCTL_DSP_STEREO, &value);
411 value = (value ? 2 : 1);
412 #ifdef SNDCTL_DSP_CHANNELS
413 }
414 #endif
415 spec->channels = value;
416
417 /* Because some drivers don't allow setting the buffer size
418 after setting the format, we must re-open the audio device
419 once we know what format and channels are supported
420 */
421 if ( DSP_ReopenAudio(this, audiodev, format, spec) < 0 ) {
422 /* Error is set by DSP_ReopenAudio() */
423 return(-1);
424 }
425
426 /* Allocate mixing buffer */
427 mixlen = spec->size;
428 mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
429 if ( mixbuf == NULL ) {
430 return(-1);
431 }
432 memset(mixbuf, spec->silence, spec->size);
433
434 #ifndef USE_BLOCKING_WRITES
435 /* Check to see if we need to use select() workaround */
436 { char *workaround;
437 workaround = getenv("SDL_DSP_NOSELECT");
438 if ( workaround ) {
439 frame_ticks = (float)(spec->samples*1000)/spec->freq;
440 next_frame = SDL_GetTicks()+frame_ticks;
441 }
442 }
443 #endif /* !USE_BLOCKING_WRITES */
444
445 /* Get the parent process id (we're the parent of the audio thread) */
446 parent = getpid();
447
448 /* We're ready to rock and roll. :-) */
449 return(0);
450 }