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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 (at) 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 */
     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 */
     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 */
     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 */
     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 
     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  */
    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