Mercurial > sdl-ios-xcode
annotate src/thread/generic/SDL_syssem.c @ 830:58b074c1bc59
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| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 16 Feb 2004 00:03:31 +0000 |
| parents | b8d311d90021 |
| children | c9b51268668f |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
|
769
b8d311d90021
Updated copyright information for 2004 (Happy New Year!)
Sam Lantinga <slouken@libsdl.org>
parents:
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changeset
|
3 Copyright (C) 1997-2004 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
| 6 modify it under the terms of the GNU Library General Public | |
| 7 License as published by the Free Software Foundation; either | |
| 8 version 2 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 Library General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU Library General Public | |
| 16 License along with this library; if not, write to the Free | |
| 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 18 | |
| 19 Sam Lantinga | |
|
252
e8157fcb3114
Updated the source with the correct e-mail address
Sam Lantinga <slouken@libsdl.org>
parents:
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20 slouken@libsdl.org |
| 0 | 21 */ |
| 22 | |
| 23 #ifdef SAVE_RCSID | |
| 24 static char rcsid = | |
| 25 "@(#) $Id$"; | |
| 26 #endif | |
| 27 | |
| 28 /* An implementation of semaphores using mutexes and condition variables */ | |
| 29 | |
| 30 #include <stdlib.h> | |
| 31 | |
| 32 #include "SDL_error.h" | |
| 33 #include "SDL_timer.h" | |
| 34 #include "SDL_thread.h" | |
| 35 #include "SDL_systhread_c.h" | |
| 36 | |
| 37 | |
| 38 #ifdef DISABLE_THREADS | |
| 39 | |
| 40 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) | |
| 41 { | |
| 42 SDL_SetError("SDL not configured with thread support"); | |
| 43 return (SDL_sem *)0; | |
| 44 } | |
| 45 | |
| 46 void SDL_DestroySemaphore(SDL_sem *sem) | |
| 47 { | |
| 48 return; | |
| 49 } | |
| 50 | |
| 51 int SDL_SemTryWait(SDL_sem *sem) | |
| 52 { | |
| 53 SDL_SetError("SDL not configured with thread support"); | |
| 54 return -1; | |
| 55 } | |
| 56 | |
| 57 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) | |
| 58 { | |
| 59 SDL_SetError("SDL not configured with thread support"); | |
| 60 return -1; | |
| 61 } | |
| 62 | |
| 63 int SDL_SemWait(SDL_sem *sem) | |
| 64 { | |
| 65 SDL_SetError("SDL not configured with thread support"); | |
| 66 return -1; | |
| 67 } | |
| 68 | |
| 69 Uint32 SDL_SemValue(SDL_sem *sem) | |
| 70 { | |
| 71 return 0; | |
| 72 } | |
| 73 | |
| 74 int SDL_SemPost(SDL_sem *sem) | |
| 75 { | |
| 76 SDL_SetError("SDL not configured with thread support"); | |
| 77 return -1; | |
| 78 } | |
| 79 | |
| 80 #else | |
| 81 | |
| 82 struct SDL_semaphore | |
| 83 { | |
| 84 Uint32 count; | |
| 85 Uint32 waiters_count; | |
| 86 SDL_mutex *count_lock; | |
| 87 SDL_cond *count_nonzero; | |
| 88 }; | |
| 89 | |
| 90 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) | |
| 91 { | |
| 92 SDL_sem *sem; | |
| 93 | |
| 94 sem = (SDL_sem *)malloc(sizeof(*sem)); | |
| 95 if ( ! sem ) { | |
| 96 SDL_OutOfMemory(); | |
| 97 return(0); | |
| 98 } | |
| 99 sem->count = initial_value; | |
| 100 sem->waiters_count = 0; | |
| 101 | |
| 102 sem->count_lock = SDL_CreateMutex(); | |
| 103 sem->count_nonzero = SDL_CreateCond(); | |
| 104 if ( ! sem->count_lock || ! sem->count_nonzero ) { | |
| 105 SDL_DestroySemaphore(sem); | |
| 106 return(0); | |
| 107 } | |
| 108 | |
| 109 return(sem); | |
| 110 } | |
| 111 | |
| 112 /* WARNING: | |
| 113 You cannot call this function when another thread is using the semaphore. | |
| 114 */ | |
| 115 void SDL_DestroySemaphore(SDL_sem *sem) | |
| 116 { | |
| 117 if ( sem ) { | |
| 118 sem->count = 0xFFFFFFFF; | |
| 119 while ( sem->waiters_count > 0) { | |
| 120 SDL_CondSignal(sem->count_nonzero); | |
| 121 SDL_Delay(10); | |
| 122 } | |
| 123 SDL_DestroyCond(sem->count_nonzero); | |
| 124 SDL_mutexP(sem->count_lock); | |
| 125 SDL_mutexV(sem->count_lock); | |
| 126 SDL_DestroyMutex(sem->count_lock); | |
| 127 free(sem); | |
| 128 } | |
| 129 } | |
| 130 | |
| 131 int SDL_SemTryWait(SDL_sem *sem) | |
| 132 { | |
| 133 int retval; | |
| 134 | |
| 135 if ( ! sem ) { | |
| 136 SDL_SetError("Passed a NULL semaphore"); | |
| 137 return -1; | |
| 138 } | |
| 139 | |
| 140 retval = SDL_MUTEX_TIMEDOUT; | |
| 141 SDL_LockMutex(sem->count_lock); | |
| 142 if ( sem->count > 0 ) { | |
| 143 --sem->count; | |
| 144 retval = 0; | |
| 145 } | |
| 146 SDL_UnlockMutex(sem->count_lock); | |
| 147 | |
| 148 return retval; | |
| 149 } | |
| 150 | |
| 151 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) | |
| 152 { | |
| 153 int retval; | |
| 154 | |
| 155 if ( ! sem ) { | |
| 156 SDL_SetError("Passed a NULL semaphore"); | |
| 157 return -1; | |
| 158 } | |
| 159 | |
| 160 /* A timeout of 0 is an easy case */ | |
| 161 if ( timeout == 0 ) { | |
| 162 return SDL_SemTryWait(sem); | |
| 163 } | |
| 164 | |
| 165 SDL_LockMutex(sem->count_lock); | |
| 166 ++sem->waiters_count; | |
| 167 retval = 0; | |
| 168 while ( (sem->count == 0) && (retval != SDL_MUTEX_TIMEDOUT) ) { | |
| 169 retval = SDL_CondWaitTimeout(sem->count_nonzero, | |
| 170 sem->count_lock, timeout); | |
| 171 } | |
| 172 --sem->waiters_count; | |
| 173 --sem->count; | |
| 174 SDL_UnlockMutex(sem->count_lock); | |
| 175 | |
| 176 return retval; | |
| 177 } | |
| 178 | |
| 179 int SDL_SemWait(SDL_sem *sem) | |
| 180 { | |
| 181 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT); | |
| 182 } | |
| 183 | |
| 184 Uint32 SDL_SemValue(SDL_sem *sem) | |
| 185 { | |
| 186 Uint32 value; | |
| 187 | |
| 188 value = 0; | |
| 189 if ( sem ) { | |
| 190 SDL_LockMutex(sem->count_lock); | |
| 191 value = sem->count; | |
| 192 SDL_UnlockMutex(sem->count_lock); | |
| 193 } | |
| 194 return value; | |
| 195 } | |
| 196 | |
| 197 int SDL_SemPost(SDL_sem *sem) | |
| 198 { | |
| 199 if ( ! sem ) { | |
| 200 SDL_SetError("Passed a NULL semaphore"); | |
| 201 return -1; | |
| 202 } | |
| 203 | |
| 204 SDL_LockMutex(sem->count_lock); | |
| 205 if ( sem->waiters_count > 0 ) { | |
| 206 SDL_CondSignal(sem->count_nonzero); | |
| 207 } | |
| 208 ++sem->count; | |
| 209 SDL_UnlockMutex(sem->count_lock); | |
| 210 | |
| 211 return 0; | |
| 212 } | |
| 213 | |
| 214 #endif /* DISABLE_THREADS */ |