| 1 | /* |
| 2 | SDL - Simple DirectMedia Layer |
| 3 | Copyright (C) 1997-2009 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@libsdl.org |
| 21 | */ |
| 22 | #include "SDL_config.h" |
| 23 | |
| 24 | #include <pthread.h> |
| 25 | #include <semaphore.h> |
| 26 | #include <errno.h> |
| 27 | |
| 28 | #include "SDL_thread.h" |
| 29 | #include "SDL_timer.h" |
| 30 | |
| 31 | /* Wrapper around POSIX 1003.1b semaphores */ |
| 32 | |
| 33 | #ifdef __MACOSX__ |
| 34 | /* Mac OS X doesn't support sem_getvalue() as of version 10.4 */ |
| 35 | #include "../generic/SDL_syssem.c" |
| 36 | #else |
| 37 | |
| 38 | struct SDL_semaphore { |
| 39 | sem_t sem; |
| 40 | }; |
| 41 | |
| 42 | /* Create a semaphore, initialized with value */ |
| 43 | SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) |
| 44 | { |
| 45 | SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem)); |
| 46 | if ( sem ) { |
| 47 | if ( sem_init(&sem->sem, 0, initial_value) < 0 ) { |
| 48 | SDL_SetError("sem_init() failed"); |
| 49 | SDL_free(sem); |
| 50 | sem = NULL; |
| 51 | } |
| 52 | } else { |
| 53 | SDL_OutOfMemory(); |
| 54 | } |
| 55 | return sem; |
| 56 | } |
| 57 | |
| 58 | void SDL_DestroySemaphore(SDL_sem *sem) |
| 59 | { |
| 60 | if ( sem ) { |
| 61 | sem_destroy(&sem->sem); |
| 62 | SDL_free(sem); |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | int SDL_SemTryWait(SDL_sem *sem) |
| 67 | { |
| 68 | int retval; |
| 69 | |
| 70 | if ( ! sem ) { |
| 71 | SDL_SetError("Passed a NULL semaphore"); |
| 72 | return -1; |
| 73 | } |
| 74 | retval = SDL_MUTEX_TIMEDOUT; |
| 75 | if ( sem_trywait(&sem->sem) == 0 ) { |
| 76 | retval = 0; |
| 77 | } |
| 78 | return retval; |
| 79 | } |
| 80 | |
| 81 | int SDL_SemWait(SDL_sem *sem) |
| 82 | { |
| 83 | int retval; |
| 84 | |
| 85 | if ( ! sem ) { |
| 86 | SDL_SetError("Passed a NULL semaphore"); |
| 87 | return -1; |
| 88 | } |
| 89 | |
| 90 | while ( ((retval = sem_wait(&sem->sem)) == -1) && (errno == EINTR) ) {} |
| 91 | if ( retval < 0 ) { |
| 92 | SDL_SetError("sem_wait() failed"); |
| 93 | } |
| 94 | return retval; |
| 95 | } |
| 96 | |
| 97 | int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) |
| 98 | { |
| 99 | int retval; |
| 100 | |
| 101 | if ( ! sem ) { |
| 102 | SDL_SetError("Passed a NULL semaphore"); |
| 103 | return -1; |
| 104 | } |
| 105 | |
| 106 | /* Try the easy cases first */ |
| 107 | if ( timeout == 0 ) { |
| 108 | return SDL_SemTryWait(sem); |
| 109 | } |
| 110 | if ( timeout == SDL_MUTEX_MAXWAIT ) { |
| 111 | return SDL_SemWait(sem); |
| 112 | } |
| 113 | |
| 114 | /* Ack! We have to busy wait... */ |
| 115 | /* FIXME: Use sem_timedwait()? */ |
| 116 | timeout += SDL_GetTicks(); |
| 117 | do { |
| 118 | retval = SDL_SemTryWait(sem); |
| 119 | if ( retval == 0 ) { |
| 120 | break; |
| 121 | } |
| 122 | SDL_Delay(1); |
| 123 | } while ( SDL_GetTicks() < timeout ); |
| 124 | |
| 125 | return retval; |
| 126 | } |
| 127 | |
| 128 | Uint32 SDL_SemValue(SDL_sem *sem) |
| 129 | { |
| 130 | int ret = 0; |
| 131 | if ( sem ) { |
| 132 | sem_getvalue(&sem->sem, &ret); |
| 133 | if ( ret < 0 ) { |
| 134 | ret = 0; |
| 135 | } |
| 136 | } |
| 137 | return (Uint32)ret; |
| 138 | } |
| 139 | |
| 140 | int SDL_SemPost(SDL_sem *sem) |
| 141 | { |
| 142 | int retval; |
| 143 | |
| 144 | if ( ! sem ) { |
| 145 | SDL_SetError("Passed a NULL semaphore"); |
| 146 | return -1; |
| 147 | } |
| 148 | |
| 149 | retval = sem_post(&sem->sem); |
| 150 | if ( retval < 0 ) { |
| 151 | SDL_SetError("sem_post() failed"); |
| 152 | } |
| 153 | return retval; |
| 154 | } |
| 155 | |
| 156 | #endif /* __MACOSX__ */ |