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 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 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 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 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