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4fd38868 RK |
1 | /* |
2 | * This file is part of DisOrder. | |
3 | * Copyright (C) 2009 Richard Kettlewell | |
4 | * | |
5 | * This program is free software: you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation, either version 3 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * This program 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 | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
17 | */ | |
18 | /** @file lib/uaudio-thread.c | |
19 | * @brief Background thread for audio processing */ | |
20 | #include "common.h" | |
21 | ||
22 | #include <pthread.h> | |
23 | #include <unistd.h> | |
24 | ||
25 | #include "uaudio.h" | |
26 | #include "log.h" | |
27 | #include "mem.h" | |
28 | ||
29 | /** @brief Number of buffers | |
30 | * | |
31 | * Must be at least 2 and should normally be at least 3. We maintain multiple | |
32 | * buffers so that we can read new data into one while the previous is being | |
33 | * played. | |
34 | */ | |
35 | #define UAUDIO_THREAD_BUFFERS 4 | |
36 | ||
37 | /** @brief Buffer data structure */ | |
38 | struct uaudio_buffer { | |
39 | /** @brief Pointer to sample data */ | |
40 | void *samples; | |
41 | ||
42 | /** @brief Count of samples */ | |
43 | size_t nsamples; | |
44 | }; | |
45 | ||
46 | /** @brief Input buffers | |
47 | * | |
48 | * This is actually a ring buffer, managed by @ref uaudio_collect_buffer and | |
49 | * @ref uaudio_play_buffer. | |
50 | * | |
51 | * Initially both pointers are 0. Whenever the pointers are equal, we | |
52 | * interpreted this as meaning that there is no data stored at all. A | |
53 | * consequence of this is that maximal occupancy is when the collect point is | |
54 | * just before the play point, so at least one buffer is always empty (hence it | |
55 | * being good for @ref UAUDIO_THREAD_BUFFERS to be at least 3). | |
56 | */ | |
57 | static struct uaudio_buffer uaudio_buffers[UAUDIO_THREAD_BUFFERS]; | |
58 | ||
59 | /** @brief Buffer to read into */ | |
60 | static unsigned uaudio_collect_buffer; | |
61 | ||
62 | /** @brief Buffer to play from */ | |
63 | static unsigned uaudio_play_buffer; | |
64 | ||
65 | /** @brief Collection thread ID */ | |
66 | static pthread_t uaudio_collect_thread; | |
67 | ||
68 | /** @brief Playing thread ID */ | |
69 | static pthread_t uaudio_play_thread; | |
70 | ||
63761c19 RK |
71 | /** @brief Flags */ |
72 | static unsigned uaudio_thread_flags; | |
73 | ||
4fd38868 RK |
74 | static uaudio_callback *uaudio_thread_collect_callback; |
75 | static uaudio_playcallback *uaudio_thread_play_callback; | |
76 | static void *uaudio_thread_userdata; | |
77 | static int uaudio_thread_started; | |
4fd38868 RK |
78 | static int uaudio_thread_collecting; |
79 | static pthread_mutex_t uaudio_thread_lock = PTHREAD_MUTEX_INITIALIZER; | |
80 | static pthread_cond_t uaudio_thread_cond = PTHREAD_COND_INITIALIZER; | |
81 | ||
82 | /** @brief Minimum number of samples per chunk */ | |
83 | static size_t uaudio_thread_min; | |
84 | ||
85 | /** @brief Maximum number of samples per chunk */ | |
86 | static size_t uaudio_thread_max; | |
87 | ||
b1f6ca8c RK |
88 | /** @brief Set when activated, clear when paused */ |
89 | static int uaudio_thread_activated; | |
90 | ||
4fd38868 RK |
91 | /** @brief Return number of buffers currently in use */ |
92 | static int uaudio_buffers_used(void) { | |
93 | return (uaudio_collect_buffer - uaudio_play_buffer) % UAUDIO_THREAD_BUFFERS; | |
94 | } | |
95 | ||
96 | /** @brief Background thread for audio collection | |
97 | * | |
98 | * Collects data while activated and communicates its status via @ref | |
99 | * uaudio_thread_collecting. | |
100 | */ | |
101 | static void *uaudio_collect_thread_fn(void attribute((unused)) *arg) { | |
102 | pthread_mutex_lock(&uaudio_thread_lock); | |
103 | while(uaudio_thread_started) { | |
104 | /* Wait until we're activatd */ | |
105 | if(!uaudio_thread_activated) { | |
106 | pthread_cond_wait(&uaudio_thread_cond, &uaudio_thread_lock); | |
107 | continue; | |
108 | } | |
109 | /* We are definitely active now */ | |
110 | uaudio_thread_collecting = 1; | |
111 | pthread_cond_broadcast(&uaudio_thread_cond); | |
b1f6ca8c | 112 | while(uaudio_thread_activated) { |
4fd38868 RK |
113 | if(uaudio_buffers_used() < UAUDIO_THREAD_BUFFERS - 1) { |
114 | /* At least one buffer is available. We release the lock while | |
115 | * collecting data so that other already-filled buffers can be played | |
116 | * without delay. */ | |
117 | struct uaudio_buffer *const b = &uaudio_buffers[uaudio_collect_buffer]; | |
118 | pthread_mutex_unlock(&uaudio_thread_lock); | |
119 | //fprintf(stderr, "C%d.", uaudio_collect_buffer); | |
120 | ||
121 | /* Keep on trying until we get the minimum required amount of data */ | |
122 | b->nsamples = 0; | |
63761c19 RK |
123 | if(uaudio_thread_activated) { |
124 | while(b->nsamples < uaudio_thread_min) { | |
125 | b->nsamples += uaudio_thread_collect_callback | |
126 | ((char *)b->samples | |
127 | + b->nsamples * uaudio_sample_size, | |
128 | uaudio_thread_max - b->nsamples, | |
129 | uaudio_thread_userdata); | |
130 | } | |
4fd38868 RK |
131 | } |
132 | pthread_mutex_lock(&uaudio_thread_lock); | |
133 | /* Advance to next buffer */ | |
134 | uaudio_collect_buffer = (1 + uaudio_collect_buffer) % UAUDIO_THREAD_BUFFERS; | |
135 | /* Awaken player */ | |
136 | pthread_cond_broadcast(&uaudio_thread_cond); | |
137 | } else | |
138 | /* No space, wait for player */ | |
139 | pthread_cond_wait(&uaudio_thread_cond, &uaudio_thread_lock); | |
140 | } | |
141 | uaudio_thread_collecting = 0; | |
142 | pthread_cond_broadcast(&uaudio_thread_cond); | |
143 | } | |
144 | pthread_mutex_unlock(&uaudio_thread_lock); | |
145 | return NULL; | |
146 | } | |
147 | ||
148 | /** @brief Background thread for audio playing | |
149 | * | |
150 | * This thread plays data as long as there is something to play. So the | |
151 | * buffers will drain to empty before deactivation completes. | |
152 | */ | |
153 | static void *uaudio_play_thread_fn(void attribute((unused)) *arg) { | |
154 | int resync = 1; | |
b1f6ca8c | 155 | unsigned last_flags = 0; |
c8197449 | 156 | unsigned char zero[uaudio_thread_max * uaudio_sample_size]; |
b1f6ca8c | 157 | memset(zero, 0, sizeof zero); |
4fd38868 | 158 | |
4fd38868 | 159 | while(uaudio_thread_started) { |
b1f6ca8c RK |
160 | // If we're paused then just play silence |
161 | if(!uaudio_thread_activated) { | |
162 | pthread_mutex_unlock(&uaudio_thread_lock); | |
163 | unsigned flags = UAUDIO_PAUSED; | |
164 | if(last_flags & UAUDIO_PLAYING) | |
165 | flags |= UAUDIO_PAUSE; | |
c8197449 | 166 | uaudio_thread_play_callback(zero, uaudio_thread_max, |
b1f6ca8c RK |
167 | last_flags = flags); |
168 | /* We expect the play callback to block for a reasonable period */ | |
169 | pthread_mutex_lock(&uaudio_thread_lock); | |
170 | continue; | |
171 | } | |
4fd38868 RK |
172 | const int used = uaudio_buffers_used(); |
173 | int go; | |
174 | ||
175 | if(resync) | |
176 | go = (used == UAUDIO_THREAD_BUFFERS - 1); | |
177 | else | |
178 | go = (used > 0); | |
179 | if(go) { | |
180 | /* At least one buffer is filled. We release the lock while playing so | |
181 | * that more collection can go on. */ | |
182 | struct uaudio_buffer *const b = &uaudio_buffers[uaudio_play_buffer]; | |
183 | pthread_mutex_unlock(&uaudio_thread_lock); | |
184 | //fprintf(stderr, "P%d.", uaudio_play_buffer); | |
185 | size_t played = 0; | |
b1f6ca8c RK |
186 | while(played < b->nsamples) { |
187 | unsigned flags = UAUDIO_PLAYING; | |
188 | if(last_flags & UAUDIO_PAUSED) | |
189 | flags |= UAUDIO_RESUME; | |
4fd38868 RK |
190 | played += uaudio_thread_play_callback((char *)b->samples |
191 | + played * uaudio_sample_size, | |
b1f6ca8c RK |
192 | b->nsamples - played, |
193 | last_flags = flags); | |
194 | } | |
4fd38868 RK |
195 | pthread_mutex_lock(&uaudio_thread_lock); |
196 | /* Move to next buffer */ | |
197 | uaudio_play_buffer = (1 + uaudio_play_buffer) % UAUDIO_THREAD_BUFFERS; | |
198 | /* Awaken collector */ | |
199 | pthread_cond_broadcast(&uaudio_thread_cond); | |
200 | resync = 0; | |
201 | } else { | |
202 | /* Insufficient data to play, wait for collector */ | |
203 | pthread_cond_wait(&uaudio_thread_cond, &uaudio_thread_lock); | |
204 | /* (Still) re-synchronizing */ | |
205 | resync = 1; | |
206 | } | |
207 | } | |
208 | pthread_mutex_unlock(&uaudio_thread_lock); | |
209 | return NULL; | |
210 | } | |
211 | ||
212 | /** @brief Create background threads for audio processing | |
213 | * @param callback Callback to collect audio data | |
214 | * @param userdata Passed to @p callback | |
215 | * @param playcallback Callback to play audio data | |
216 | * @param min Minimum number of samples to play in a chunk | |
217 | * @param max Maximum number of samples to play in a chunk | |
b1f6ca8c | 218 | * @param flags Flags (not currently used) |
4fd38868 RK |
219 | * |
220 | * @p callback will be called multiple times in quick succession if necessary | |
221 | * to gather at least @p min samples. Equally @p playcallback may be called | |
222 | * repeatedly in quick succession to play however much was received in a single | |
223 | * chunk. | |
224 | */ | |
225 | void uaudio_thread_start(uaudio_callback *callback, | |
226 | void *userdata, | |
227 | uaudio_playcallback *playcallback, | |
228 | size_t min, | |
63761c19 RK |
229 | size_t max, |
230 | unsigned flags) { | |
4fd38868 RK |
231 | int e; |
232 | uaudio_thread_collect_callback = callback; | |
233 | uaudio_thread_userdata = userdata; | |
234 | uaudio_thread_play_callback = playcallback; | |
235 | uaudio_thread_min = min; | |
236 | uaudio_thread_max = max; | |
63761c19 | 237 | uaudio_thread_flags = flags; |
4fd38868 | 238 | uaudio_thread_started = 1; |
b1f6ca8c | 239 | uaudio_thread_activated = 0; |
4fd38868 | 240 | for(int n = 0; n < UAUDIO_THREAD_BUFFERS; ++n) |
8e93ddd1 RK |
241 | uaudio_buffers[n].samples = xcalloc_noptr(uaudio_thread_max, |
242 | uaudio_sample_size); | |
4fd38868 RK |
243 | uaudio_collect_buffer = uaudio_play_buffer = 0; |
244 | if((e = pthread_create(&uaudio_collect_thread, | |
245 | NULL, | |
246 | uaudio_collect_thread_fn, | |
247 | NULL))) | |
2e9ba080 | 248 | disorder_fatal(e, "pthread_create"); |
4fd38868 RK |
249 | if((e = pthread_create(&uaudio_play_thread, |
250 | NULL, | |
251 | uaudio_play_thread_fn, | |
252 | NULL))) | |
2e9ba080 | 253 | disorder_fatal(e, "pthread_create"); |
4fd38868 RK |
254 | } |
255 | ||
256 | /** @brief Shut down background threads for audio processing */ | |
257 | void uaudio_thread_stop(void) { | |
258 | void *result; | |
259 | ||
260 | pthread_mutex_lock(&uaudio_thread_lock); | |
261 | uaudio_thread_activated = 0; | |
262 | uaudio_thread_started = 0; | |
263 | pthread_cond_broadcast(&uaudio_thread_cond); | |
264 | pthread_mutex_unlock(&uaudio_thread_lock); | |
265 | pthread_join(uaudio_collect_thread, &result); | |
266 | pthread_join(uaudio_play_thread, &result); | |
267 | for(int n = 0; n < UAUDIO_THREAD_BUFFERS; ++n) | |
268 | xfree(uaudio_buffers[n].samples); | |
269 | } | |
270 | ||
271 | /** @brief Activate audio output */ | |
272 | void uaudio_thread_activate(void) { | |
273 | pthread_mutex_lock(&uaudio_thread_lock); | |
274 | uaudio_thread_activated = 1; | |
275 | pthread_cond_broadcast(&uaudio_thread_cond); | |
4fd38868 RK |
276 | pthread_mutex_unlock(&uaudio_thread_lock); |
277 | } | |
278 | ||
279 | /** @brief Deactivate audio output */ | |
280 | void uaudio_thread_deactivate(void) { | |
281 | pthread_mutex_lock(&uaudio_thread_lock); | |
b1f6ca8c | 282 | uaudio_thread_activated = 0; |
4fd38868 | 283 | pthread_cond_broadcast(&uaudio_thread_cond); |
4fd38868 RK |
284 | pthread_mutex_unlock(&uaudio_thread_lock); |
285 | } | |
286 | ||
287 | /* | |
288 | Local Variables: | |
289 | c-basic-offset:2 | |
290 | comment-column:40 | |
291 | fill-column:79 | |
292 | indent-tabs-mode:nil | |
293 | End: | |
294 | */ |