Mercurial > sdl-ios-xcode
annotate src/thread/generic/SDL_sysmutex.c @ 1312:c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
I batch edited these files, so please let me know if I've accidentally removed anybody's
credit here.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 01 Feb 2006 06:32:25 +0000 |
| parents | b8d311d90021 |
| children | 450721ad5436 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
|
1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
3 Copyright (C) 1997-2006 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
|
1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
6 modify it under the terms of the GNU Lesser General Public |
| 0 | 7 License as published by the Free Software Foundation; either |
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1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
8 version 2.1 of the License, or (at your option) any later version. |
| 0 | 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 | |
|
1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
13 Lesser General Public License for more details. |
| 0 | 14 |
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1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
15 You should have received a copy of the GNU Lesser General Public |
|
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
16 License along with this library; if not, write to the Free Software |
|
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 0 | 18 |
| 19 Sam Lantinga | |
|
252
e8157fcb3114
Updated the source with the correct e-mail address
Sam Lantinga <slouken@libsdl.org>
parents:
0
diff
changeset
|
20 slouken@libsdl.org |
| 0 | 21 */ |
| 22 | |
| 23 /* An implementation of mutexes using semaphores */ | |
| 24 | |
| 25 #include <stdio.h> | |
| 26 #include <stdlib.h> | |
| 27 | |
| 28 #include "SDL_error.h" | |
| 29 #include "SDL_thread.h" | |
| 30 #include "SDL_systhread_c.h" | |
| 31 | |
| 32 | |
| 33 struct SDL_mutex { | |
| 34 int recursive; | |
| 35 Uint32 owner; | |
| 36 SDL_sem *sem; | |
| 37 }; | |
| 38 | |
| 39 /* Create a mutex */ | |
| 40 SDL_mutex *SDL_CreateMutex(void) | |
| 41 { | |
| 42 SDL_mutex *mutex; | |
| 43 | |
| 44 /* Allocate mutex memory */ | |
| 45 mutex = (SDL_mutex *)malloc(sizeof(*mutex)); | |
| 46 if ( mutex ) { | |
| 47 /* Create the mutex semaphore, with initial value 1 */ | |
| 48 mutex->sem = SDL_CreateSemaphore(1); | |
| 49 mutex->recursive = 0; | |
| 50 mutex->owner = 0; | |
| 51 if ( ! mutex->sem ) { | |
| 52 free(mutex); | |
| 53 mutex = NULL; | |
| 54 } | |
| 55 } else { | |
| 56 SDL_OutOfMemory(); | |
| 57 } | |
| 58 return mutex; | |
| 59 } | |
| 60 | |
| 61 /* Free the mutex */ | |
| 62 void SDL_DestroyMutex(SDL_mutex *mutex) | |
| 63 { | |
| 64 if ( mutex ) { | |
| 65 if ( mutex->sem ) { | |
| 66 SDL_DestroySemaphore(mutex->sem); | |
| 67 } | |
| 68 free(mutex); | |
| 69 } | |
| 70 } | |
| 71 | |
| 72 /* Lock the semaphore */ | |
| 73 int SDL_mutexP(SDL_mutex *mutex) | |
| 74 { | |
| 75 #ifdef DISABLE_THREADS | |
| 76 return 0; | |
| 77 #else | |
| 78 Uint32 this_thread; | |
| 79 | |
| 80 if ( mutex == NULL ) { | |
| 81 SDL_SetError("Passed a NULL mutex"); | |
| 82 return -1; | |
| 83 } | |
| 84 | |
| 85 this_thread = SDL_ThreadID(); | |
| 86 if ( mutex->owner == this_thread ) { | |
| 87 ++mutex->recursive; | |
| 88 } else { | |
| 89 /* The order of operations is important. | |
| 90 We set the locking thread id after we obtain the lock | |
| 91 so unlocks from other threads will fail. | |
| 92 */ | |
| 93 SDL_SemWait(mutex->sem); | |
| 94 mutex->owner = this_thread; | |
| 95 mutex->recursive = 0; | |
| 96 } | |
| 97 | |
| 98 return 0; | |
| 99 #endif /* DISABLE_THREADS */ | |
| 100 } | |
| 101 | |
| 102 /* Unlock the mutex */ | |
| 103 int SDL_mutexV(SDL_mutex *mutex) | |
| 104 { | |
| 105 #ifdef DISABLE_THREADS | |
| 106 return 0; | |
| 107 #else | |
| 108 if ( mutex == NULL ) { | |
| 109 SDL_SetError("Passed a NULL mutex"); | |
| 110 return -1; | |
| 111 } | |
| 112 | |
| 113 /* If we don't own the mutex, we can't unlock it */ | |
| 114 if ( SDL_ThreadID() != mutex->owner ) { | |
| 115 SDL_SetError("mutex not owned by this thread"); | |
| 116 return -1; | |
| 117 } | |
| 118 | |
| 119 if ( mutex->recursive ) { | |
| 120 --mutex->recursive; | |
| 121 } else { | |
| 122 /* The order of operations is important. | |
| 123 First reset the owner so another thread doesn't lock | |
| 124 the mutex and set the ownership before we reset it, | |
| 125 then release the lock semaphore. | |
| 126 */ | |
| 127 mutex->owner = 0; | |
| 128 SDL_SemPost(mutex->sem); | |
| 129 } | |
| 130 return 0; | |
| 131 #endif /* DISABLE_THREADS */ | |
| 132 } |