1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997-2006 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 /* An implementation of semaphores using mutexes and condition variables */
28
29 #include "SDL_timer.h"
30 #include "SDL_thread.h"
31 #include "SDL_systhread_c.h"
32
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 #include <kos/sem.h>
79
80 struct SDL_semaphore
81 {
82 semaphore_t sem;
83 };
84
SDL_CreateSemaphore(Uint32 initial_value)85 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
86 {
87 return (SDL_sem *)sem_create(initial_value);
88 }
89
90 /* WARNING:
91 You cannot call this function when another thread is using the semaphore.
92 */
SDL_DestroySemaphore(SDL_sem * sem)93 void SDL_DestroySemaphore(SDL_sem *sem)
94 {
95 if ( ! sem ) {
96 SDL_SetError("Passed a NULL semaphore");
97 return;
98 }
99
100 sem_destroy(&sem->sem);
101 }
102
SDL_SemTryWait(SDL_sem * sem)103 int SDL_SemTryWait(SDL_sem *sem)
104 {
105 int retval;
106
107 if ( ! sem ) {
108 SDL_SetError("Passed a NULL semaphore");
109 return -1;
110 }
111
112 retval = sem_trywait(&sem->sem);
113 if (retval==0) return 0;
114 else return SDL_MUTEX_TIMEDOUT;
115
116 return retval;
117 }
118
SDL_SemWaitTimeout(SDL_sem * sem,Uint32 timeout)119 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
120 {
121 int retval;
122
123 if ( ! sem ) {
124 SDL_SetError("Passed a NULL semaphore");
125 return -1;
126 }
127
128 /* A timeout of 0 is an easy case */
129 if ( timeout == 0 ) {
130 return SDL_SemTryWait(sem);
131 }
132
133 retval = sem_wait_timed(&sem->sem,timeout);
134 if (retval==-1) retval= SDL_MUTEX_TIMEDOUT;
135
136 return retval;
137 }
138
SDL_SemWait(SDL_sem * sem)139 int SDL_SemWait(SDL_sem *sem)
140 {
141 int retval;
142
143 if ( ! sem ) {
144 SDL_SetError("Passed a NULL semaphore");
145 return -1;
146 }
147
148 while ( ((retval = sem_wait(&sem->sem)) == -1) && (errno == EINTR) ) {}
149 return retval;
150 }
151
SDL_SemValue(SDL_sem * sem)152 Uint32 SDL_SemValue(SDL_sem *sem)
153 {
154 if ( ! sem ) {
155 SDL_SetError("Passed a NULL semaphore");
156 return -1;
157 }
158
159 return sem_count(&sem->sem);
160 }
161
SDL_SemPost(SDL_sem * sem)162 int SDL_SemPost(SDL_sem *sem)
163 {
164 if ( ! sem ) {
165 SDL_SetError("Passed a NULL semaphore");
166 return -1;
167 }
168
169 sem_signal(&sem->sem);
170 return 0;
171 }
172
173 #endif /* SDL_THREADS_DISABLED */
174