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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: ausys-sdl.c,v 1.2 2002/02/02 22:43:17 mdw Exp $ |
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4 | * |
5 | * Unix-specific (SDL) audio handling |
6 | * |
7 | * (c) 2002 Mark Wooding |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Jog: Programming for a jogging machine. |
13 | * |
14 | * Jog is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * Jog is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with Jog; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
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29 | /*----- Header files ------------------------------------------------------*/ |
30 | |
31 | #ifdef HAVE_CONFIG_H |
32 | # include "config.h" |
33 | #endif |
34 | |
35 | #include <errno.h> |
36 | #include <stdio.h> |
37 | #include <string.h> |
38 | |
39 | #include <sys/types.h> |
40 | #include <sys/time.h> |
41 | #include <unistd.h> |
42 | #include <pthread.h> |
43 | |
44 | #include <SDL.h> |
45 | |
46 | #include <mLib/alloc.h> |
47 | #include <mLib/bits.h> |
48 | #include <mLib/sub.h> |
49 | #include <mLib/trace.h> |
50 | |
51 | #include "au.h" |
52 | #include "ausys.h" |
53 | #include "err.h" |
54 | #include "jog.h" |
55 | |
56 | /*----- Data structures ---------------------------------------------------*/ |
57 | |
58 | /* --- Queue of samples to play --- */ |
59 | |
60 | typedef struct qnode { |
61 | struct qnode *next; /* Next item in the queue */ |
62 | au_data *a; /* Pointer to sample data */ |
63 | } qnode; |
64 | |
65 | /*----- Global variables --------------------------------------------------*/ |
66 | |
67 | const char *const ausys_suffix = "wav"; |
68 | |
69 | /*----- Static data -------------------------------------------------------*/ |
70 | |
71 | static SDL_AudioSpec auspec; /* Driver's selected parameters */ |
72 | static qnode *qhead = 0, *qtail = 0; /* Queue of samples to play */ |
73 | static qnode *qfree = 0; /* Queue of samples to free */ |
74 | |
75 | static pthread_t tid_free; /* The sample-freeing thread */ |
76 | static pthread_mutex_t mx_free; /* Mutex for @qfree@ */ |
77 | static pthread_cond_t cv_free; /* More sample data to free */ |
78 | |
79 | static pthread_mutex_t mx_sub; /* Protects mLib @sub@ functions */ |
80 | |
81 | /*----- Thread structure --------------------------------------------------* |
82 | * |
83 | * SDL makes a buffer-stuffing thread that @fill@ is run from. This function |
84 | * reads samples to play from the queue at @qhead@. Hence @qhead@ must be |
85 | * locked when it's modified, using @SDL_LockAudio@. |
86 | * |
87 | * In order to keep latency down when new sample data is wanted, we don't do |
88 | * potentially tedious things like freeing sample data blocks in the @fill@ |
89 | * thread. Instead, there's a queue of sample blocks which need freeing, and |
90 | * a separate thread @dofree@ which processes the queue. The queue, @qfree@ |
91 | * is locked by @mx_free@. When new nodes are added to @qfree@, the |
92 | * condition @cv_free@ is signalled. |
93 | * |
94 | * Finally, the mLib `sub' module isn't thread-safe, so it's locked |
95 | * separately by @mx_sub@. |
96 | * |
97 | * There's an ordering on mutexes. If you want more than one mutex at a |
98 | * time, you must lock the greatest first. The ordering is: |
99 | * |
100 | * SDL_Audio > free > sub |
101 | */ |
102 | |
103 | /*----- Main code ---------------------------------------------------------*/ |
104 | |
105 | /* --- @fill@ --- * |
106 | * |
107 | * Arguments: @void *u@ = user data (ignored) |
108 | * @octet *q@ = pointer to buffer to fill in |
109 | * @int qsz@ = size of the buffer |
110 | * |
111 | * Returns: --- |
112 | * |
113 | * Use: Fills an audio buffer with precomputed stuff. |
114 | */ |
115 | |
116 | static void fill(void *u, octet *q, int qsz) |
117 | { |
118 | static const octet *p = 0; /* Current place in current sample */ |
119 | static size_t sz = 0; /* How far to go in current sample */ |
120 | qnode *qf = 0, **qft = &qf; /* Samples we've finished with */ |
121 | |
122 | /* --- If @p@ is null we need to get a new sample --- */ |
123 | |
124 | if (!p && qhead) { |
125 | T( trace(T_AUSYS, "ausys: begin playing `%s'", SYM_NAME(qhead->a->s)); ) |
126 | p = qhead->a->p; |
127 | sz = qhead->a->sz; |
128 | } |
129 | |
130 | /* --- Main queue-filling loop --- */ |
131 | |
132 | while (qsz) { |
133 | size_t n; |
134 | |
135 | /* --- If the queue is empty, play silence --- */ |
136 | |
137 | if (!p) { |
138 | memset(q, auspec.silence, qsz); |
139 | break; |
140 | } |
141 | |
142 | /* --- Fill the buffer with my sample --- */ |
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143 | |
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144 | n = qsz; |
145 | if (n > sz) |
146 | n = sz; |
147 | memcpy(q, p, n); |
148 | p += n; q += n; |
149 | sz -= n; qsz -= n; |
150 | |
151 | /* --- If the sample is used up, throw it away --- */ |
152 | |
153 | if (!sz) { |
154 | qnode *qq = qhead; |
155 | qhead = qq->next; |
156 | if (!qhead) |
157 | qtail = 0; |
158 | T( trace(T_AUSYS, "ausys: put `%s' on free list", |
159 | SYM_NAME(qq->a->s)); ) |
160 | *qft = qq; |
161 | qft = &qq->next; |
162 | if (qhead) { |
163 | T( trace(T_AUSYS, "ausys: begin playing `%s'", |
164 | SYM_NAME(qhead->a->s)); ) |
165 | p = qhead->a->p; |
166 | sz = qhead->a->sz; |
167 | } else { |
168 | T( trace(T_AUSYS, "ausys: sample queue is empty"); ) |
169 | p = 0; |
170 | sz = 0; |
171 | } |
172 | } |
173 | } |
174 | |
175 | /* --- Finally dump freed samples, all in one go --- */ |
176 | |
177 | if (qf) { |
178 | pthread_mutex_lock(&mx_free); |
179 | *qft = qfree; |
180 | qfree = qf; |
181 | pthread_mutex_unlock(&mx_free); |
182 | pthread_cond_signal(&cv_free); |
183 | } |
184 | } |
185 | |
186 | /* --- @dofree@ --- * |
187 | * |
188 | * Arguments: @void *u@ = unused pointer |
189 | * |
190 | * Returns: An unused pointer. |
191 | * |
192 | * Use: Frees unwanted sample queue nodes. |
193 | */ |
194 | |
195 | static void *dofree(void *u) |
196 | { |
197 | qnode *q, *qq; |
198 | |
199 | pthread_mutex_lock(&mx_free); |
200 | for (;;) { |
201 | T( trace(T_AUSYS, "ausys: dofree sleeping"); ) |
202 | pthread_cond_wait(&cv_free, &mx_free); |
203 | T( trace(T_AUSYS, "ausys: dofree woken: work to do"); ) |
204 | |
205 | while (qfree) { |
206 | q = qfree; |
207 | qfree = 0; |
208 | pthread_mutex_lock(&mx_sub); |
209 | while (q) { |
210 | qq = q->next; |
211 | T( trace(T_AUSYS, "ausys: freeing `%s'", SYM_NAME(q->a->s)); ) |
212 | au_free_unlocked(q->a); |
213 | DESTROY(q); |
214 | q = qq; |
215 | } |
216 | pthread_mutex_unlock(&mx_sub); |
217 | } |
218 | } |
219 | } |
220 | |
221 | /* --- @ausys_init@ --- * |
222 | * |
223 | * Arguments: --- |
224 | * |
225 | * Returns: --- |
226 | * |
227 | * Use: Does any initialization required by the system-specific audio |
228 | * handler. |
229 | */ |
230 | |
231 | void ausys_init(void) |
232 | { |
233 | SDL_AudioSpec want; |
234 | pthread_attr_t ta; |
235 | int e; |
236 | |
237 | /* --- Crank up the sample-freeing thread --- */ |
238 | |
239 | if ((e = pthread_mutex_init(&mx_free, 0)) != 0 || |
240 | (e = pthread_mutex_init(&mx_sub, 0)) != 0 || |
241 | (e = pthread_cond_init(&cv_free, 0)) != 0 || |
242 | (e = pthread_attr_init(&ta)) != 0 || |
243 | (e = pthread_attr_setdetachstate(&ta, PTHREAD_CREATE_DETACHED)) != 0 || |
244 | (e = pthread_create(&tid_free, &ta, dofree, 0)) != 0) { |
245 | err_report(ERR_AUDIO, ERRAU_INIT, e, |
246 | "couldn't create audio threads: %s", strerror(errno)); |
247 | exit(EXIT_FAILURE); |
248 | } |
249 | pthread_attr_destroy(&ta); |
250 | |
251 | /* --- Crank up the SDL audio subsystem --- */ |
252 | |
253 | if (SDL_Init(SDL_INIT_AUDIO | SDL_INIT_NOPARACHUTE)) { |
254 | err_report(ERR_AUDIO, ERRAU_INIT, 0, |
255 | "couldn't initialize SDL audio: %s", SDL_GetError()); |
256 | exit(EXIT_FAILURE); |
257 | } |
258 | |
259 | /* --- Open the audio device --- */ |
260 | |
261 | want.freq = 8000; |
262 | want.format = AUDIO_U8; |
263 | want.channels = 1; |
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264 | want.samples = 1024; |
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265 | want.callback = fill; |
266 | want.userdata = 0; |
267 | |
268 | if (SDL_OpenAudio(&want, &auspec)) { |
269 | err_report(ERR_AUDIO, ERRAU_INIT, 0, |
270 | "couldn't open audio device: %s", SDL_GetError()); |
271 | exit(EXIT_FAILURE); |
272 | } |
273 | |
274 | /* --- Prepare whatever needs to be done --- */ |
275 | |
276 | SDL_PauseAudio(0); |
277 | |
278 | T( trace(T_AUSYS, "ausys: initalized ok"); ) |
279 | } |
280 | |
281 | /* --- @ausys_shutdown@ --- * |
282 | * |
283 | * Arguments: --- |
284 | * |
285 | * Returns: --- |
286 | * |
287 | * Use: Does any tidying up required. |
288 | */ |
289 | |
290 | void ausys_shutdown(void) |
291 | { |
292 | /* --- Busy-wait until sound buffer empties --- */ |
293 | |
294 | while (qhead) { |
295 | struct timeval tv = { 0, 100000 }; |
296 | select(0, 0, 0, 0, &tv); |
297 | } |
298 | |
299 | /* --- Shut stuff down --- */ |
300 | |
301 | pthread_cancel(tid_free); |
302 | SDL_CloseAudio(); |
303 | SDL_Quit(); |
304 | |
305 | T( trace(T_AUSYS, "ausys: shut down ok"); ) |
306 | } |
307 | |
308 | /* --- @ausys_lock@, @ausys_unlock@ --- * |
309 | * |
310 | * Arguments: --- |
311 | * |
312 | * Returns: --- |
313 | * |
314 | * Use: Locks or unlocks the audio subsystem. This protects the |
315 | * audio queue from becoming corrupted during all the tedious |
316 | * asynchronous stuff. |
317 | */ |
318 | |
319 | void ausys_lock(void) |
320 | { |
321 | pthread_mutex_lock(&mx_free); |
322 | pthread_mutex_lock(&mx_sub); |
323 | T( trace(T_AUSYS, "ausys: acquired lock"); ) |
324 | } |
325 | |
326 | void ausys_unlock(void) |
327 | { |
328 | pthread_mutex_unlock(&mx_sub); |
329 | pthread_mutex_unlock(&mx_free); |
330 | T( trace(T_AUSYS, "ausys: released lock"); ) |
331 | } |
332 | |
333 | /* --- @ausys_decode@ --- * |
334 | * |
335 | * Arguments: @au_sample *s@ = pointer to sample block |
336 | * @const void *p@ = pointer to sample file contents |
337 | * @size_t sz@ = size of sample file contents |
338 | * |
339 | * Returns: Pointer to a sample data structure. |
340 | * |
341 | * Use: Decodes a WAV file into something the system-specific layer |
342 | * actually wants to deal with. |
343 | */ |
344 | |
345 | au_data *ausys_decode(au_sample *s, const void *p, size_t sz) |
346 | { |
347 | au_data *a; |
348 | SDL_AudioCVT cvt; |
349 | SDL_AudioSpec spec; |
350 | SDL_RWops *rw; |
351 | Uint8 *buf; |
352 | Uint32 len; |
353 | void *q; |
354 | |
355 | /* --- Firstly, extract the audio data from the WAV file --- */ |
356 | |
357 | rw = SDL_RWFromMem((void *)p, sz); |
358 | if (!SDL_LoadWAV_RW(rw, 1, &spec, &buf, &len)) { |
359 | err_report(ERR_AUDIO, ERRAU_OPEN, 0, |
360 | "can't read WAV file for `%s': %s", |
361 | SYM_NAME(s), SDL_GetError()); |
362 | goto fail_0; |
363 | } |
364 | |
365 | /* --- Now convert that to the driver's expected format --- */ |
366 | |
367 | if (SDL_BuildAudioCVT(&cvt, spec.format, spec.channels, spec.freq, |
368 | auspec.format, auspec.channels, auspec.freq) == -1) { |
369 | err_report(ERR_AUDIO, ERRAU_OPEN, 0, |
370 | "can't build conversion structure for `%s': %s", |
371 | SYM_NAME(s), SDL_GetError()); |
372 | goto fail_1; |
373 | } |
374 | |
375 | cvt.buf = xmalloc(len * cvt.len_mult); |
376 | cvt.len = len; |
377 | memcpy(cvt.buf, buf, len); |
378 | SDL_FreeWAV(buf); |
379 | |
380 | if (SDL_ConvertAudio(&cvt)) { |
381 | err_report(ERR_AUDIO, ERRAU_OPEN, 0, |
382 | "can't convert `%s': %s", SYM_NAME(s), SDL_GetError()); |
383 | goto fail_2; |
384 | } |
385 | |
386 | /* --- Now fiddle with buffers --- */ |
387 | |
388 | sz = len * cvt.len_ratio; |
389 | if (cvt.len_ratio >= 1) |
390 | q = cvt.buf; |
391 | else { |
392 | q = xmalloc(sz); |
393 | memcpy(q, cvt.buf, sz); |
394 | xfree(cvt.buf); |
395 | } |
396 | |
397 | /* --- Construct a new node --- */ |
398 | |
399 | pthread_mutex_lock(&mx_sub); |
400 | a = CREATE(au_data); |
401 | pthread_mutex_unlock(&mx_sub); |
402 | a->p = q; |
403 | a->sz = sz; |
404 | |
405 | T( trace(T_AUSYS, "ausys: decoded `%s' ok", SYM_NAME(s)); ) |
406 | return (a); |
407 | |
408 | /* --- Tidy up after errors --- */ |
409 | |
410 | fail_2: |
411 | xfree(cvt.buf); |
412 | goto fail_0; |
413 | fail_1: |
414 | SDL_FreeWAV(buf); |
415 | fail_0: |
416 | return (0); |
417 | } |
418 | |
419 | /* --- @ausys_queue@ --- * |
420 | * |
421 | * Arguments: @au_data *a@ = an audio thingy to play |
422 | * |
423 | * Returns: --- |
424 | * |
425 | * Use: Queues an audio sample to be played. The sample should be |
426 | * freed (with @au_free@) when it's no longer wanted. |
427 | */ |
428 | |
429 | void ausys_queue(au_data *a) |
430 | { |
431 | qnode *q; |
432 | |
433 | pthread_mutex_lock(&mx_sub); |
434 | q = CREATE(qnode); |
435 | pthread_mutex_unlock(&mx_sub); |
436 | q->next = 0; |
437 | q->a = a; |
438 | SDL_LockAudio(); |
439 | if (qtail) |
440 | qtail->next = q; |
441 | else |
442 | qhead = q; |
443 | qtail = q; |
444 | SDL_UnlockAudio(); |
445 | T( trace(T_AUSYS, "ausys: queuing `%s'", SYM_NAME(a->s)); ) |
446 | } |
447 | |
448 | /* --- @ausys_free@ --- * |
449 | * |
450 | * Arguments: @au_data *a@ = an audio thingy to free |
451 | * |
452 | * Returns: --- |
453 | * |
454 | * Use: Frees a decoded audio sample. |
455 | */ |
456 | |
457 | void ausys_free(au_data *a) |
458 | { |
459 | xfree(a->p); |
460 | DESTROY(a); |
461 | T( trace(T_AUSYS, "ausys: freeing data for `%s' ok", SYM_NAME(a->s)); ) |
462 | } |
463 | |
464 | /*----- That's all, folks -------------------------------------------------*/ |