1 /* Copyright (c) 2012, The Linux Foundation. All rights reserved.
2 *
3 * Redistribution and use in source and binary forms, with or without
4 * modification, are permitted provided that the following conditions are
5 * met:
6 * * Redistributions of source code must retain the above copyright
7 * notice, this list of conditions and the following disclaimer.
8 * * Redistributions in binary form must reproduce the above
9 * copyright notice, this list of conditions and the following
10 * disclaimer in the documentation and/or other materials provided
11 * with the distribution.
12 * * Neither the name of The Linux Foundation nor the names of its
13 * contributors may be used to endorse or promote products derived
14 * from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
23 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
25 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
26 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 */
29
30 #ifndef __QCAMERA_SEMAPHORE_H__
31 #define __QCAMERA_SEMAPHORE_H__
32
33 #ifdef __cplusplus
34 extern "C" {
35 #endif
36
37 /* Implement semaphore with mutex and conditional variable.
38 * Reason being, POSIX semaphore on Android are not used or
39 * well tested.
40 */
41
42 typedef struct {
43 int val;
44 pthread_mutex_t mutex;
45 pthread_cond_t cond;
46 } cam_semaphore_t;
47
cam_sem_init(cam_semaphore_t * s,int n)48 static inline void cam_sem_init(cam_semaphore_t *s, int n)
49 {
50 pthread_mutex_init(&(s->mutex), NULL);
51 pthread_cond_init(&(s->cond), NULL);
52 s->val = n;
53 }
54
cam_sem_post(cam_semaphore_t * s)55 static inline void cam_sem_post(cam_semaphore_t *s)
56 {
57 pthread_mutex_lock(&(s->mutex));
58 s->val++;
59 pthread_cond_signal(&(s->cond));
60 pthread_mutex_unlock(&(s->mutex));
61 }
62
cam_sem_wait(cam_semaphore_t * s)63 static inline int cam_sem_wait(cam_semaphore_t *s)
64 {
65 int rc = 0;
66 pthread_mutex_lock(&(s->mutex));
67 while (s->val == 0)
68 rc = pthread_cond_wait(&(s->cond), &(s->mutex));
69 s->val--;
70 pthread_mutex_unlock(&(s->mutex));
71 return rc;
72 }
73
cam_sem_destroy(cam_semaphore_t * s)74 static inline void cam_sem_destroy(cam_semaphore_t *s)
75 {
76 pthread_mutex_destroy(&(s->mutex));
77 pthread_cond_destroy(&(s->cond));
78 s->val = 0;
79 }
80
81 #ifdef __cplusplus
82 }
83 #endif
84
85 #endif /* __QCAMERA_SEMAPHORE_H__ */
86