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 #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 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 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 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 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 } 99 100 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
