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 // System dependencies
34 #include <pthread.h>
35 #include <errno.h>
36 #include "cam_cond.h"
37
38 #ifdef __cplusplus
39 extern "C" {
40 #endif
41
42 /* Implement semaphore with mutex and conditional variable.
43 * Reason being, POSIX semaphore on Android are not used or
44 * well tested.
45 */
46
47 typedef struct {
48 int val;
49 pthread_mutex_t mutex;
50 pthread_cond_t cond;
51 } cam_semaphore_t;
52
cam_sem_init(cam_semaphore_t * s,int n)53 static inline void cam_sem_init(cam_semaphore_t *s, int n)
54 {
55 pthread_mutex_init(&(s->mutex), NULL);
56 PTHREAD_COND_INIT(&(s->cond));
57 s->val = n;
58 }
59
cam_sem_post(cam_semaphore_t * s)60 static inline void cam_sem_post(cam_semaphore_t *s)
61 {
62 pthread_mutex_lock(&(s->mutex));
63 s->val++;
64 pthread_cond_signal(&(s->cond));
65 pthread_mutex_unlock(&(s->mutex));
66 }
67
cam_sem_wait(cam_semaphore_t * s)68 static inline int cam_sem_wait(cam_semaphore_t *s)
69 {
70 int rc = 0;
71 pthread_mutex_lock(&(s->mutex));
72 while (s->val == 0)
73 rc = pthread_cond_wait(&(s->cond), &(s->mutex));
74 s->val--;
75 pthread_mutex_unlock(&(s->mutex));
76 return rc;
77 }
78
cam_sem_timedwait(cam_semaphore_t * s,const struct timespec * abs_timeout)79 static inline int cam_sem_timedwait(cam_semaphore_t *s, const struct timespec *abs_timeout)
80 {
81 int rc = 0;
82 pthread_mutex_lock(&(s->mutex));
83 while (s->val == 0 && rc != ETIMEDOUT)
84 rc = pthread_cond_timedwait(&(s->cond), &(s->mutex), abs_timeout);
85
86 if (s->val > 0)
87 s->val--;
88
89 pthread_mutex_unlock(&(s->mutex));
90
91 /* sem_timedwait returns -1 for failure case, and failure code is in errno
92 */
93 if (rc != 0) {
94 errno = rc;
95 rc = -1;
96 }
97 return rc;
98 }
99
cam_sem_destroy(cam_semaphore_t * s)100 static inline void cam_sem_destroy(cam_semaphore_t *s)
101 {
102 pthread_mutex_destroy(&(s->mutex));
103 pthread_cond_destroy(&(s->cond));
104 s->val = 0;
105 }
106
107 #ifdef __cplusplus
108 }
109 #endif
110
111 #endif /* __QCAMERA_SEMAPHORE_H__ */
112