/
SDL_syssem.c
176 lines (150 loc) · 3.45 KB
/
SDL_syssem.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2006 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Sam Lantinga
slouken@libsdl.org
*/
#include "SDL_config.h"
#include <pthread.h>
#include <semaphore.h>
#include "SDL_thread.h"
#include "SDL_timer.h"
/* Wrapper around POSIX 1003.1b semaphores */
#ifdef __MACOSX__
#define USE_NAMED_SEMAPHORES 1
#include <unistd.h>
#endif
struct SDL_semaphore {
sem_t *sem;
#if !USE_NAMED_SEMAPHORES
sem_t sem_data;
#endif
};
/* Create a semaphore, initialized with value */
SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem));
if ( sem ) {
#if USE_NAMED_SEMAPHORES
static int semnum = 0;
char name[32];
SDL_snprintf(name, SDL_arraysize(name), "/SDL_sem-%d-%4.4d", getpid(), semnum++);
sem->sem = sem_open(name, O_CREAT, 0600, initial_value);
if ( sem->sem == (sem_t *)SEM_FAILED ) {
SDL_SetError("sem_open(%s) failed", name);
SDL_free(sem);
sem = NULL;
} else {
sem_unlink(name);
}
#else
if ( sem_init(&sem->sem_data, 0, initial_value) < 0 ) {
SDL_SetError("sem_init() failed");
SDL_free(sem);
sem = NULL;
} else {
sem->sem = &sem->sem_data;
}
#endif /* USE_NAMED_SEMAPHORES */
} else {
SDL_OutOfMemory();
}
return sem;
}
void SDL_DestroySemaphore(SDL_sem *sem)
{
if ( sem ) {
#if USE_NAMED_SEMAPHORES
sem_close(sem->sem);
#else
sem_destroy(sem->sem);
#endif
SDL_free(sem);
}
}
int SDL_SemTryWait(SDL_sem *sem)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
retval = SDL_MUTEX_TIMEDOUT;
if ( sem_trywait(sem->sem) == 0 ) {
retval = 0;
}
return retval;
}
int SDL_SemWait(SDL_sem *sem)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
retval = sem_wait(sem->sem);
if ( retval < 0 ) {
SDL_SetError("sem_wait() failed");
}
return retval;
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
/* Try the easy cases first */
if ( timeout == 0 ) {
return SDL_SemTryWait(sem);
}
if ( timeout == SDL_MUTEX_MAXWAIT ) {
return SDL_SemWait(sem);
}
/* Ack! We have to busy wait... */
timeout += SDL_GetTicks();
do {
retval = SDL_SemTryWait(sem);
if ( retval == 0 ) {
break;
}
SDL_Delay(1);
} while ( SDL_GetTicks() < timeout );
return retval;
}
Uint32 SDL_SemValue(SDL_sem *sem)
{
int ret = 0;
if ( sem ) {
sem_getvalue(sem->sem, &ret);
if ( ret < 0 ) {
ret = 0;
}
}
return (Uint32)ret;
}
int SDL_SemPost(SDL_sem *sem)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
retval = sem_post(sem->sem);
if ( retval < 0 ) {
SDL_SetError("sem_post() failed");
}
return retval;
}