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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 #include "SDL_config.h"
23 
24 #include <sys/time.h>
25 #include <unistd.h>
26 #include <errno.h>
27 #include <pthread.h>
28 
29 #include "SDL_thread.h"
30 #include "SDL_sysmutex_c.h"
31 
32 struct SDL_cond
33 {
34 	pthread_cond_t cond;
35 };
36 
37 /* Create a condition variable */
SDL_CreateCond(void)38 SDL_cond * SDL_CreateCond(void)
39 {
40 	SDL_cond *cond;
41 
42 	cond = (SDL_cond *) SDL_malloc(sizeof(SDL_cond));
43 	if ( cond ) {
44 		if ( pthread_cond_init(&cond->cond, NULL) < 0 ) {
45 			SDL_SetError("pthread_cond_init() failed");
46 			SDL_free(cond);
47 			cond = NULL;
48 		}
49 	}
50 	return(cond);
51 }
52 
53 /* Destroy a condition variable */
SDL_DestroyCond(SDL_cond * cond)54 void SDL_DestroyCond(SDL_cond *cond)
55 {
56 	if ( cond ) {
57 		pthread_cond_destroy(&cond->cond);
58 		SDL_free(cond);
59 	}
60 }
61 
62 /* Restart one of the threads that are waiting on the condition variable */
SDL_CondSignal(SDL_cond * cond)63 int SDL_CondSignal(SDL_cond *cond)
64 {
65 	int retval;
66 
67 	if ( ! cond ) {
68 		SDL_SetError("Passed a NULL condition variable");
69 		return -1;
70 	}
71 
72 	retval = 0;
73 	if ( pthread_cond_signal(&cond->cond) != 0 ) {
74 		SDL_SetError("pthread_cond_signal() failed");
75 		retval = -1;
76 	}
77 	return retval;
78 }
79 
80 /* Restart all threads that are waiting on the condition variable */
SDL_CondBroadcast(SDL_cond * cond)81 int SDL_CondBroadcast(SDL_cond *cond)
82 {
83 	int retval;
84 
85 	if ( ! cond ) {
86 		SDL_SetError("Passed a NULL condition variable");
87 		return -1;
88 	}
89 
90 	retval = 0;
91 	if ( pthread_cond_broadcast(&cond->cond) != 0 ) {
92 		SDL_SetError("pthread_cond_broadcast() failed");
93 		retval = -1;
94 	}
95 	return retval;
96 }
97 
SDL_CondWaitTimeout(SDL_cond * cond,SDL_mutex * mutex,Uint32 ms)98 int SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms)
99 {
100 	int retval;
101 	struct timeval delta;
102 	struct timespec abstime;
103 
104 	if ( ! cond ) {
105 		SDL_SetError("Passed a NULL condition variable");
106 		return -1;
107 	}
108 
109 	gettimeofday(&delta, NULL);
110 
111 	abstime.tv_sec = delta.tv_sec + (ms/1000);
112 	abstime.tv_nsec = (delta.tv_usec + (ms%1000) * 1000) * 1000;
113         if ( abstime.tv_nsec > 1000000000 ) {
114           abstime.tv_sec += 1;
115           abstime.tv_nsec -= 1000000000;
116         }
117 
118   tryagain:
119 	retval = pthread_cond_timedwait(&cond->cond, &mutex->id, &abstime);
120 	switch (retval) {
121 	    case EINTR:
122 		goto tryagain;
123 		break;
124 	    case ETIMEDOUT:
125 		retval = SDL_MUTEX_TIMEDOUT;
126 		break;
127 	    case 0:
128 		break;
129 	    default:
130 		SDL_SetError("pthread_cond_timedwait() failed");
131 		retval = -1;
132 		break;
133 	}
134 	return retval;
135 }
136 
137 /* Wait on the condition variable, unlocking the provided mutex.
138    The mutex must be locked before entering this function!
139  */
SDL_CondWait(SDL_cond * cond,SDL_mutex * mutex)140 int SDL_CondWait(SDL_cond *cond, SDL_mutex *mutex)
141 {
142 	int retval;
143 
144 	if ( ! cond ) {
145 		SDL_SetError("Passed a NULL condition variable");
146 		return -1;
147 	}
148 
149 	retval = 0;
150 	if ( pthread_cond_wait(&cond->cond, &mutex->id) != 0 ) {
151 		SDL_SetError("pthread_cond_wait() failed");
152 		retval = -1;
153 	}
154 	return retval;
155 }
156