1 /* Copyright (c) 2012, 2016, 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 // System dependencies
34 #include <pthread.h>
35
36 #ifdef __cplusplus
37 extern "C" {
38 #endif
39
40 /* Implement semaphore with mutex and conditional variable.
41 * Reason being, POSIX semaphore on Android are not used or
42 * well tested.
43 */
44
45 typedef struct {
46 int val;
47 pthread_mutex_t mutex;
48 pthread_cond_t cond;
49 } cam_semaphore_t;
50
cam_sem_init(cam_semaphore_t * s,int n)51 static inline void cam_sem_init(cam_semaphore_t *s, int n)
52 {
53 pthread_mutex_init(&(s->mutex), NULL);
54 pthread_cond_init(&(s->cond), NULL);
55 s->val = n;
56 }
57
cam_sem_post(cam_semaphore_t * s)58 static inline void cam_sem_post(cam_semaphore_t *s)
59 {
60 pthread_mutex_lock(&(s->mutex));
61 s->val++;
62 pthread_cond_signal(&(s->cond));
63 pthread_mutex_unlock(&(s->mutex));
64 }
65
cam_sem_wait(cam_semaphore_t * s)66 static inline int cam_sem_wait(cam_semaphore_t *s)
67 {
68 int rc = 0;
69 pthread_mutex_lock(&(s->mutex));
70 while (s->val == 0)
71 rc = pthread_cond_wait(&(s->cond), &(s->mutex));
72 s->val--;
73 pthread_mutex_unlock(&(s->mutex));
74 return rc;
75 }
76
cam_sem_destroy(cam_semaphore_t * s)77 static inline void cam_sem_destroy(cam_semaphore_t *s)
78 {
79 pthread_mutex_destroy(&(s->mutex));
80 pthread_cond_destroy(&(s->cond));
81 s->val = 0;
82 }
83
84 #ifdef __cplusplus
85 }
86 #endif
87
88 #endif /* __QCAMERA_SEMAPHORE_H__ */
89