Mercurial > sdl-ios-xcode
annotate src/thread/generic/SDL_sysmutex.c @ 769:b8d311d90021
Updated copyright information for 2004 (Happy New Year!)
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 04 Jan 2004 16:49:27 +0000 |
| parents | f6ffac90895c |
| 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
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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 | |
|
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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 mutexes using semaphores */ | |
| 29 | |
| 30 #include <stdio.h> | |
| 31 #include <stdlib.h> | |
| 32 | |
| 33 #include "SDL_error.h" | |
| 34 #include "SDL_thread.h" | |
| 35 #include "SDL_systhread_c.h" | |
| 36 | |
| 37 | |
| 38 struct SDL_mutex { | |
| 39 int recursive; | |
| 40 Uint32 owner; | |
| 41 SDL_sem *sem; | |
| 42 }; | |
| 43 | |
| 44 /* Create a mutex */ | |
| 45 SDL_mutex *SDL_CreateMutex(void) | |
| 46 { | |
| 47 SDL_mutex *mutex; | |
| 48 | |
| 49 /* Allocate mutex memory */ | |
| 50 mutex = (SDL_mutex *)malloc(sizeof(*mutex)); | |
| 51 if ( mutex ) { | |
| 52 /* Create the mutex semaphore, with initial value 1 */ | |
| 53 mutex->sem = SDL_CreateSemaphore(1); | |
| 54 mutex->recursive = 0; | |
| 55 mutex->owner = 0; | |
| 56 if ( ! mutex->sem ) { | |
| 57 free(mutex); | |
| 58 mutex = NULL; | |
| 59 } | |
| 60 } else { | |
| 61 SDL_OutOfMemory(); | |
| 62 } | |
| 63 return mutex; | |
| 64 } | |
| 65 | |
| 66 /* Free the mutex */ | |
| 67 void SDL_DestroyMutex(SDL_mutex *mutex) | |
| 68 { | |
| 69 if ( mutex ) { | |
| 70 if ( mutex->sem ) { | |
| 71 SDL_DestroySemaphore(mutex->sem); | |
| 72 } | |
| 73 free(mutex); | |
| 74 } | |
| 75 } | |
| 76 | |
| 77 /* Lock the semaphore */ | |
| 78 int SDL_mutexP(SDL_mutex *mutex) | |
| 79 { | |
| 80 #ifdef DISABLE_THREADS | |
| 81 return 0; | |
| 82 #else | |
| 83 Uint32 this_thread; | |
| 84 | |
| 85 if ( mutex == NULL ) { | |
| 86 SDL_SetError("Passed a NULL mutex"); | |
| 87 return -1; | |
| 88 } | |
| 89 | |
| 90 this_thread = SDL_ThreadID(); | |
| 91 if ( mutex->owner == this_thread ) { | |
| 92 ++mutex->recursive; | |
| 93 } else { | |
| 94 /* The order of operations is important. | |
| 95 We set the locking thread id after we obtain the lock | |
| 96 so unlocks from other threads will fail. | |
| 97 */ | |
| 98 SDL_SemWait(mutex->sem); | |
| 99 mutex->owner = this_thread; | |
| 100 mutex->recursive = 0; | |
| 101 } | |
| 102 | |
| 103 return 0; | |
| 104 #endif /* DISABLE_THREADS */ | |
| 105 } | |
| 106 | |
| 107 /* Unlock the mutex */ | |
| 108 int SDL_mutexV(SDL_mutex *mutex) | |
| 109 { | |
| 110 #ifdef DISABLE_THREADS | |
| 111 return 0; | |
| 112 #else | |
| 113 if ( mutex == NULL ) { | |
| 114 SDL_SetError("Passed a NULL mutex"); | |
| 115 return -1; | |
| 116 } | |
| 117 | |
| 118 /* If we don't own the mutex, we can't unlock it */ | |
| 119 if ( SDL_ThreadID() != mutex->owner ) { | |
| 120 SDL_SetError("mutex not owned by this thread"); | |
| 121 return -1; | |
| 122 } | |
| 123 | |
| 124 if ( mutex->recursive ) { | |
| 125 --mutex->recursive; | |
| 126 } else { | |
| 127 /* The order of operations is important. | |
| 128 First reset the owner so another thread doesn't lock | |
| 129 the mutex and set the ownership before we reset it, | |
| 130 then release the lock semaphore. | |
| 131 */ | |
| 132 mutex->owner = 0; | |
| 133 SDL_SemPost(mutex->sem); | |
| 134 } | |
| 135 return 0; | |
| 136 #endif /* DISABLE_THREADS */ | |
| 137 } |