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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