e14743d1 |
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__ */ |