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
*/
/* Semaphore functions using the OS/2 API */
#include <stdio.h>
#include <stdlib.h>
#define INCL_DOS
#define INCL_DOSERRORS
#define INCL_DOSSEMAPHORES
#include <os2.h>
#include "SDL_error.h"
#include "SDL_thread.h"
#include "SDL_timer.h"
struct SDL_semaphore {
HMTX id;
HEV changed;
Uint32 value;
};
/* Create a semaphore */
DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_sem *sem;
ULONG ulrc;
/* Allocate sem memory */
sem = (SDL_sem *)malloc(sizeof(*sem));
if ( sem ) {
/* Create the mutex semaphore */
ulrc = DosCreateMutexSem(NULL,&(sem->id),0,TRUE);
if ( ulrc ) {
SDL_SetError("Couldn't create semaphore");
free(sem);
sem = NULL;
} else
{
DosCreateEventSem(NULL, &(sem->changed), 0, FALSE);
sem->value = initial_value;
DosReleaseMutexSem(sem->id);
}
} else {
SDL_OutOfMemory();
}
return(sem);
}
/* Free the semaphore */
DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem)
{
if ( sem ) {
if ( sem->id ) {
DosCloseEventSem(sem->changed);
DosCloseMutexSem(sem->id);
sem->id = 0;
}
free(sem);
}
}
DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
ULONG ulrc;
if ( ! sem ) {
SDL_SetError("Passed a NULL sem");
return -1;
}
if ( timeout == SDL_MUTEX_MAXWAIT ) {
while (1) {
ulrc = DosRequestMutexSem(sem->id, SEM_INDEFINITE_WAIT);
if (ulrc) {
/* if error waiting mutex */
SDL_SetError("DosRequestMutexSem() failed");
return -1;
} else if (sem->value) {
sem->value--;
DosReleaseMutexSem(sem->id);
return 0;
} else {
ULONG ulPostCount;
DosResetEventSem(sem->changed, &ulPostCount);
DosReleaseMutexSem(sem->id);
/* continue waiting until somebody posts the semaphore */
DosWaitEventSem(sem->changed, SEM_INDEFINITE_WAIT);
}
}
} else
if ( timeout == 0 )
{
ulrc = DosRequestMutexSem(sem->id, SEM_INDEFINITE_WAIT);
if (ulrc==NO_ERROR)
{
if (sem->value)
{
sem->value--;
DosReleaseMutexSem(sem->id);
return 0;
} else
{
DosReleaseMutexSem(sem->id);
return SDL_MUTEX_TIMEDOUT;
}
} else
{
SDL_SetError("DosRequestMutexSem() failed");
return -1;
}
} else {
ulrc = DosRequestMutexSem(sem->id, SEM_INDEFINITE_WAIT);
if (ulrc) {
/* if error waiting mutex */
SDL_SetError("DosRequestMutexSem() failed");
return -1;
} else
if (sem->value) {
sem->value--;
DosReleaseMutexSem(sem->id);
return 0;
} else {
ULONG ulPostCount;
DosResetEventSem(sem->changed, &ulPostCount);
DosReleaseMutexSem(sem->id);
/* continue waiting until somebody posts the semaphore */
ulrc = DosWaitEventSem(sem->changed, timeout);
if (ulrc==NO_ERROR)
return 0;
else
return SDL_MUTEX_TIMEDOUT;
}
}
/* never reached */
return -1;
}
DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem)
{
return SDL_SemWaitTimeout(sem, 0);
}
DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem)
{
return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
}
/* Returns the current count of the semaphore */
DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL sem");
return 0;
}
return sem->value;
}
DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL sem");
return -1;
}
if ( DosRequestMutexSem(sem->id,SEM_INDEFINITE_WAIT) ) {
SDL_SetError("DosRequestMutexSem() failed");
return -1;
}
sem->value++;
DosPostEventSem(sem->changed);
DosReleaseMutexSem(sem->id);
return 0;
}