1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997-2012 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
23 #include <errno.h>
24
25 #include "SDL_config.h"
26
27 /* RISC OS semiphores based on linux code */
28
29
30 #include "SDL_timer.h"
31 #include "SDL_thread.h"
32 #include "SDL_systhread_c.h"
33
34 #if !SDL_THREADS_DISABLED
35
SDL_CreateSemaphore(Uint32 initial_value)36 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
37 {
38 SDL_SetError("SDL not configured with thread support");
39 return (SDL_sem *)0;
40 }
41
SDL_DestroySemaphore(SDL_sem * sem)42 void SDL_DestroySemaphore(SDL_sem *sem)
43 {
44 return;
45 }
46
SDL_SemTryWait(SDL_sem * sem)47 int SDL_SemTryWait(SDL_sem *sem)
48 {
49 SDL_SetError("SDL not configured with thread support");
50 return -1;
51 }
52
SDL_SemWaitTimeout(SDL_sem * sem,Uint32 timeout)53 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
54 {
55 SDL_SetError("SDL not configured with thread support");
56 return -1;
57 }
58
SDL_SemWait(SDL_sem * sem)59 int SDL_SemWait(SDL_sem *sem)
60 {
61 SDL_SetError("SDL not configured with thread support");
62 return -1;
63 }
64
SDL_SemValue(SDL_sem * sem)65 Uint32 SDL_SemValue(SDL_sem *sem)
66 {
67 return 0;
68 }
69
SDL_SemPost(SDL_sem * sem)70 int SDL_SemPost(SDL_sem *sem)
71 {
72 SDL_SetError("SDL not configured with thread support");
73 return -1;
74 }
75
76 #else
77
78
79 #include <unistd.h> /* For getpid() */
80 #include <pthread.h>
81 #include <semaphore.h>
82
83 struct SDL_semaphore {
84 sem_t *sem;
85 sem_t sem_data;
86 };
87
88 /* Create a semaphore, initialized with value */
SDL_CreateSemaphore(Uint32 initial_value)89 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
90 {
91 SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem));
92 if ( sem ) {
93 if ( sem_init(&sem->sem_data, 0, initial_value) < 0 ) {
94 SDL_SetError("sem_init() failed");
95 SDL_free(sem);
96 sem = NULL;
97 } else {
98 sem->sem = &sem->sem_data;
99 }
100 } else {
101 SDL_OutOfMemory();
102 }
103 return sem;
104 }
105
SDL_DestroySemaphore(SDL_sem * sem)106 void SDL_DestroySemaphore(SDL_sem *sem)
107 {
108 if ( sem ) {
109 sem_destroy(sem->sem);
110 SDL_free(sem);
111 }
112 }
113
SDL_SemTryWait(SDL_sem * sem)114 int SDL_SemTryWait(SDL_sem *sem)
115 {
116 int retval;
117
118 if ( ! sem ) {
119 SDL_SetError("Passed a NULL semaphore");
120 return -1;
121 }
122 retval = SDL_MUTEX_TIMEDOUT;
123 if ( sem_trywait(sem->sem) == 0 ) {
124 retval = 0;
125 }
126 return retval;
127 }
128
SDL_SemWait(SDL_sem * sem)129 int SDL_SemWait(SDL_sem *sem)
130 {
131 int retval;
132
133 if ( ! sem ) {
134 SDL_SetError("Passed a NULL semaphore");
135 return -1;
136 }
137
138 while ( ((retval = sem_wait(sem->sem)) == -1) && (errno == EINTR) ) {}
139 if ( retval < 0 ) {
140 SDL_SetError("sem_wait() failed");
141 }
142 return retval;
143 }
144
SDL_SemWaitTimeout(SDL_sem * sem,Uint32 timeout)145 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
146 {
147 int retval;
148
149 if ( ! sem ) {
150 SDL_SetError("Passed a NULL semaphore");
151 return -1;
152 }
153
154 /* Try the easy cases first */
155 if ( timeout == 0 ) {
156 return SDL_SemTryWait(sem);
157 }
158 if ( timeout == SDL_MUTEX_MAXWAIT ) {
159 return SDL_SemWait(sem);
160 }
161
162 /* Ack! We have to busy wait... */
163 timeout += SDL_GetTicks();
164 do {
165 retval = SDL_SemTryWait(sem);
166 if ( retval == 0 ) {
167 break;
168 }
169 SDL_Delay(1);
170 } while ( SDL_GetTicks() < timeout );
171
172 return retval;
173 }
174
SDL_SemValue(SDL_sem * sem)175 Uint32 SDL_SemValue(SDL_sem *sem)
176 {
177 int ret = 0;
178 if ( sem ) {
179 sem_getvalue(sem->sem, &ret);
180 if ( ret < 0 ) {
181 ret = 0;
182 }
183 }
184 return (Uint32)ret;
185 }
186
SDL_SemPost(SDL_sem * sem)187 int SDL_SemPost(SDL_sem *sem)
188 {
189 int retval;
190
191 if ( ! sem ) {
192 SDL_SetError("Passed a NULL semaphore");
193 return -1;
194 }
195
196 retval = sem_post(sem->sem);
197 if ( retval < 0 ) {
198 SDL_SetError("sem_post() failed");
199 }
200 return retval;
201 }
202
203 #endif /* !SDL_THREADS_DISABLED */
204