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 #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 }