1 /* 2 SDL - Simple DirectMedia Layer 3 Copyright (C) 1997-2012 Sam Lantinga 4 5 This library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 This library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with this library; if not, write to the Free Software 17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 18 19 Sam Lantinga 20 slouken (at) libsdl.org 21 */ 22 23 #include <errno.h> 24 25 #include "SDL_config.h" 26 27 /* An implementation of semaphores using mutexes and condition variables */ 28 29 #include "SDL_timer.h" 30 #include "SDL_thread.h" 31 #include "SDL_systhread_c.h" 32 33 34 #if SDL_THREADS_DISABLED 35 36 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) 37 { 38 SDL_SetError("SDL not configured with thread support"); 39 return (SDL_sem *)0; 40 } 41 42 void SDL_DestroySemaphore(SDL_sem *sem) 43 { 44 return; 45 } 46 47 int SDL_SemTryWait(SDL_sem *sem) 48 { 49 SDL_SetError("SDL not configured with thread support"); 50 return -1; 51 } 52 53 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) 54 { 55 SDL_SetError("SDL not configured with thread support"); 56 return -1; 57 } 58 59 int SDL_SemWait(SDL_sem *sem) 60 { 61 SDL_SetError("SDL not configured with thread support"); 62 return -1; 63 } 64 65 Uint32 SDL_SemValue(SDL_sem *sem) 66 { 67 return 0; 68 } 69 70 int SDL_SemPost(SDL_sem *sem) 71 { 72 SDL_SetError("SDL not configured with thread support"); 73 return -1; 74 } 75 76 #else 77 78 #include <kos/sem.h> 79 80 struct SDL_semaphore 81 { 82 semaphore_t sem; 83 }; 84 85 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) 86 { 87 return (SDL_sem *)sem_create(initial_value); 88 } 89 90 /* WARNING: 91 You cannot call this function when another thread is using the semaphore. 92 */ 93 void SDL_DestroySemaphore(SDL_sem *sem) 94 { 95 if ( ! sem ) { 96 SDL_SetError("Passed a NULL semaphore"); 97 return; 98 } 99 100 sem_destroy(&sem->sem); 101 } 102 103 int SDL_SemTryWait(SDL_sem *sem) 104 { 105 int retval; 106 107 if ( ! sem ) { 108 SDL_SetError("Passed a NULL semaphore"); 109 return -1; 110 } 111 112 retval = sem_trywait(&sem->sem); 113 if (retval==0) return 0; 114 else return SDL_MUTEX_TIMEDOUT; 115 116 return retval; 117 } 118 119 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) 120 { 121 int retval; 122 123 if ( ! sem ) { 124 SDL_SetError("Passed a NULL semaphore"); 125 return -1; 126 } 127 128 /* A timeout of 0 is an easy case */ 129 if ( timeout == 0 ) { 130 return SDL_SemTryWait(sem); 131 } 132 133 retval = sem_wait_timed(&sem->sem,timeout); 134 if (retval==-1) retval= SDL_MUTEX_TIMEDOUT; 135 136 return retval; 137 } 138 139 int SDL_SemWait(SDL_sem *sem) 140 { 141 int retval; 142 143 if ( ! sem ) { 144 SDL_SetError("Passed a NULL semaphore"); 145 return -1; 146 } 147 148 while ( ((retval = sem_wait(&sem->sem)) == -1) && (errno == EINTR) ) {} 149 return retval; 150 } 151 152 Uint32 SDL_SemValue(SDL_sem *sem) 153 { 154 if ( ! sem ) { 155 SDL_SetError("Passed a NULL semaphore"); 156 return -1; 157 } 158 159 return sem_count(&sem->sem); 160 } 161 162 int SDL_SemPost(SDL_sem *sem) 163 { 164 if ( ! sem ) { 165 SDL_SetError("Passed a NULL semaphore"); 166 return -1; 167 } 168 169 sem_signal(&sem->sem); 170 return 0; 171 } 172 173 #endif /* SDL_THREADS_DISABLED */ 174
