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SDL_syssem.c
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SDL_syssem.c
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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997-2006 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"
/* An implementation of semaphores using mutexes and condition variables */
#include "SDL_thread.h"
#include "SDL_systhread_c.h"
struct SDL_semaphore
{
struct SignalSemaphore Sem;
};
#undef D
#define D(x)
SDL_sem *
SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_sem *sem;
sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
if (!sem) {
SDL_OutOfMemory();
return (0);
}
D(bug("Creating semaphore %lx...\n", sem));
SDL_memset(sem, 0, sizeof(*sem));
InitSemaphore(&sem->Sem);
return (sem);
}
void
SDL_DestroySemaphore(SDL_sem * sem)
{
D(bug("Destroying semaphore %lx...\n", sem));
if (sem) {
// Condizioni per liberare i task in attesa?
SDL_free(sem);
}
}
int
SDL_SemTryWait(SDL_sem * sem)
{
if (!sem) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
D(bug("TryWait semaphore...%lx\n", sem));
ObtainSemaphore(&sem->Sem);
// ReleaseSemaphore(&sem->Sem);
return 1;
}
int
SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
{
int retval;
if (!sem) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
D(bug("WaitTimeout (%ld) semaphore...%lx\n", timeout, sem));
/* A timeout of 0 is an easy case */
if (timeout == 0) {
ObtainSemaphore(&sem->Sem);
return 1;
}
if (!(retval = AttemptSemaphore(&sem->Sem))) {
SDL_Delay(timeout);
retval = AttemptSemaphore(&sem->Sem);
}
if (retval == TRUE) {
// ReleaseSemaphore(&sem->Sem);
retval = 1;
}
return retval;
}
int
SDL_SemWait(SDL_sem * sem)
{
ObtainSemaphore(&sem->Sem);
return 0;
}
Uint32
SDL_SemValue(SDL_sem * sem)
{
Uint32 value;
value = 0;
if (sem) {
#ifdef STORMC4_WOS
value = sem->Sem.ssppc_SS.ss_NestCount;
#else
value = sem->Sem.ss_NestCount;
#endif
}
return value;
}
int
SDL_SemPost(SDL_sem * sem)
{
if (!sem) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
D(bug("SemPost semaphore...%lx\n", sem));
ReleaseSemaphore(&sem->Sem);
return 0;
}
/* vi: set ts=4 sw=4 expandtab: */