SDL_syssem.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2006 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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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
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Lesser General Public License for more details.
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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
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Sam Lantinga
slouken@libsdl.org
*/
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#include "SDL_config.h"
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/* An implementation of semaphores using mutexes and condition variables */
#include "SDL_timer.h"
#include "SDL_thread.h"
#include "SDL_systhread_c.h"
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#if SDL_THREADS_DISABLED
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SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_SetError("SDL not configured with thread support");
return (SDL_sem *)0;
}
void SDL_DestroySemaphore(SDL_sem *sem)
{
return;
}
int SDL_SemTryWait(SDL_sem *sem)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
int SDL_SemWait(SDL_sem *sem)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
Uint32 SDL_SemValue(SDL_sem *sem)
{
return 0;
}
int SDL_SemPost(SDL_sem *sem)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
#else
#include <kos/sem.h>
struct SDL_semaphore
{
semaphore_t sem;
};
SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
return (SDL_sem *)sem_create(initial_value);
}
/* WARNING:
You cannot call this function when another thread is using the semaphore.
*/
void SDL_DestroySemaphore(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return;
}
sem_destroy(&sem->sem);
}
int SDL_SemTryWait(SDL_sem *sem)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
retval = sem_trywait(&sem->sem);
if (retval==0) return 0;
else return SDL_MUTEX_TIMEDOUT;
return retval;
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
/* A timeout of 0 is an easy case */
if ( timeout == 0 ) {
return SDL_SemTryWait(sem);
}
retval = sem_wait_timed(&sem->sem,timeout);
if (retval==-1) retval= SDL_MUTEX_TIMEDOUT;
return retval;
}
int SDL_SemWait(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
sem_wait(&sem->sem);
return 0;
}
Uint32 SDL_SemValue(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
return sem_count(&sem->sem);
}
int SDL_SemPost(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
sem_signal(&sem->sem);
return 0;
}
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#endif /* SDL_THREADS_DISABLED */