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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2012 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 <errno.h>
#include <sys/time.h>
#include "SDL_thread.h"
#include "SDL_timer.h"
/* Wrapper around POSIX 1003.1b semaphores */
#ifdef __MACOSX__
/* Mac OS X doesn't support sem_getvalue() as of version 10.4 */
#include "../generic/SDL_syssem.c"
#else
struct SDL_semaphore {
sem_t sem;
};
/* 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 ( sem_init(&sem->sem, 0, initial_value) < 0 ) {
SDL_SetError("sem_init() failed");
SDL_free(sem);
sem = NULL;
}
} else {
SDL_OutOfMemory();
}
return sem;
}
void SDL_DestroySemaphore(SDL_sem *sem)
{
if ( sem ) {
sem_destroy(&sem->sem);
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;
}
while ( ((retval = sem_wait(&sem->sem)) == -1) && (errno == EINTR) ) {}
if ( retval < 0 ) {
SDL_SetError("sem_wait() failed");
}
return retval;
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
int retval;
#ifdef HAVE_SEM_TIMEDWAIT
struct timeval now;
struct timespec ts_timeout;
#else
Uint32 end;
#endif
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);
}
#ifdef HAVE_SEM_TIMEDWAIT
/* Setup the timeout. sem_timedwait doesn't wait for
* a lapse of time, but until we reach a certain time.
* This time is now plus the timeout.
*/
gettimeofday(&now, NULL);
/* Add our timeout to current time */
now.tv_usec += (timeout % 1000) * 1000;
now.tv_sec += timeout / 1000;
/* Wrap the second if needed */
if ( now.tv_usec >= 1000000 ) {
now.tv_usec -= 1000000;
now.tv_sec ++;
}
/* Convert to timespec */
ts_timeout.tv_sec = now.tv_sec;
ts_timeout.tv_nsec = now.tv_usec * 1000;
/* Wait. */
do
retval = sem_timedwait(&sem->sem, &ts_timeout);
while (retval == -1 && errno == EINTR);
if (retval == -1)
SDL_SetError(strerror(errno));
#else
end = SDL_GetTicks() + timeout;
while ((retval = SDL_SemTryWait(sem)) == SDL_MUTEX_TIMEDOUT) {
if ((SDL_GetTicks() - end) >= 0) {
break;
}
SDL_Delay(0);
}
#endif /* HAVE_SEM_TIMEDWAIT */
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;
}
#endif /* __MACOSX__ */
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