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SDL_syssem.c
195 lines (164 loc) · 3.93 KB
/
SDL_syssem.c
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/*
SDL - Simple DirectMedia Layer
Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
slouken@devolution.com
*/
#ifdef SAVE_RCSID
static char rcsid =
"@(#) $Id$";
#endif
/* Semaphore functions using the Win32 API */
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include "SDL_error.h"
#include "SDL_thread.h"
#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
/* No semaphores on Windows CE earlier than 3.0, hmm... */
/* Create a semaphore */
SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_SetError("Semaphores not supported on WinCE");
return(NULL);
}
/* Free the semaphore */
void SDL_DestroySemaphore(SDL_sem *sem)
{
return;
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
SDL_SetError("Semaphores not supported on WinCE");
return(-1);
}
int SDL_SemTryWait(SDL_sem *sem)
{
return SDL_SemWaitTimeout(sem, 0);
}
int SDL_SemWait(SDL_sem *sem)
{
return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
}
/* Returns the current count of the semaphore */
Uint32 SDL_SemValue(SDL_sem *sem)
{
return(0);
}
int SDL_SemPost(SDL_sem *sem)
{
SDL_SetError("Semaphores not supported on WinCE");
return(-1);
}
#else
struct SDL_semaphore {
HANDLE id;
Uint32 volatile count;
};
/* Create a semaphore */
SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_sem *sem;
/* Allocate sem memory */
sem = (SDL_sem *)malloc(sizeof(*sem));
if ( sem ) {
/* Create the semaphore, with max value 32K */
sem->id = CreateSemaphore(NULL, initial_value, 32*1024, NULL);
sem->count = initial_value;
if ( ! sem->id ) {
SDL_SetError("Couldn't create semaphore");
free(sem);
sem = NULL;
}
} else {
SDL_OutOfMemory();
}
return(sem);
}
/* Free the semaphore */
void SDL_DestroySemaphore(SDL_sem *sem)
{
if ( sem ) {
if ( sem->id ) {
CloseHandle(sem->id);
sem->id = 0;
}
free(sem);
}
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
int retval;
DWORD dwMilliseconds;
if ( ! sem ) {
SDL_SetError("Passed a NULL sem");
return -1;
}
if ( timeout == SDL_MUTEX_MAXWAIT ) {
dwMilliseconds = INFINITE;
} else {
dwMilliseconds = (DWORD)timeout;
}
switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
case WAIT_OBJECT_0:
--sem->count;
retval = 0;
break;
case WAIT_TIMEOUT:
retval = SDL_MUTEX_TIMEDOUT;
break;
default:
SDL_SetError("WaitForSingleObject() failed");
retval = -1;
break;
}
return retval;
}
int SDL_SemTryWait(SDL_sem *sem)
{
return SDL_SemWaitTimeout(sem, 0);
}
int SDL_SemWait(SDL_sem *sem)
{
return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
}
/* Returns the current count of the semaphore */
Uint32 SDL_SemValue(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL sem");
return 0;
}
return sem->count;
}
int SDL_SemPost(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL sem");
return -1;
}
/* Increase the counter in the first place, because
* after a successful release the semaphore may
* immediately get destroyed by another thread which
* is waiting for this semaphore.
*/
++sem->count;
if ( ReleaseSemaphore(sem->id, 1, NULL) == FALSE ) {
--sem->count; /* restore */
SDL_SetError("ReleaseSemaphore() failed");
return -1;
}
return 0;
}
#endif /* _WIN32_WCE */