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SDL_syssem.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2010 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
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slouken@libsdl.org
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*/
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#include "SDL_config.h"
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/* Semaphore functions using the Win32 API */
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#include "../../core/windows/SDL_windows.h"
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#include "SDL_thread.h"
#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
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#include "win_ce_semaphore.h"
#endif
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struct SDL_semaphore
{
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#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
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SYNCHHANDLE id;
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};
/* Create a semaphore */
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SDL_sem *
SDL_CreateSemaphore(Uint32 initial_value)
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SDL_sem *sem;
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/* Allocate sem memory */
sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
if (sem) {
/* Create the semaphore, with max value 32K */
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#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
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sem->id = CreateSemaphoreCE(NULL, initial_value, 32 * 1024, NULL);
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sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
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sem->count = initial_value;
if (!sem->id) {
SDL_SetError("Couldn't create semaphore");
SDL_free(sem);
sem = NULL;
}
} else {
SDL_OutOfMemory();
}
return (sem);
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}
/* Free the semaphore */
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void
SDL_DestroySemaphore(SDL_sem * sem)
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if (sem) {
if (sem->id) {
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#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
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CloseSynchHandle(sem->id);
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CloseHandle(sem->id);
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sem->id = 0;
}
SDL_free(sem);
}
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}
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int
SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
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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;
}
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#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
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switch (WaitForSemaphoreCE(sem->id, dwMilliseconds)) {
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switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
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case WAIT_OBJECT_0:
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InterlockedDecrement(&sem->count);
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retval = 0;
break;
case WAIT_TIMEOUT:
retval = SDL_MUTEX_TIMEDOUT;
break;
default:
SDL_SetError("WaitForSingleObject() failed");
retval = -1;
break;
}
return retval;
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}
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int
SDL_SemTryWait(SDL_sem * sem)
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{
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return SDL_SemWaitTimeout(sem, 0);
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}
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int
SDL_SemWait(SDL_sem * sem)
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{
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return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
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}
/* Returns the current count of the semaphore */
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Uint32
SDL_SemValue(SDL_sem * sem)
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{
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if (!sem) {
SDL_SetError("Passed a NULL sem");
return 0;
}
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return (Uint32)sem->count;
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}
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int
SDL_SemPost(SDL_sem * sem)
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{
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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.
*/
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InterlockedIncrement(&sem->count);
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#if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
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if (ReleaseSemaphoreCE(sem->id, 1, NULL) == FALSE) {
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if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
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InterlockedDecrement(&sem->count); /* restore */
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SDL_SetError("ReleaseSemaphore() failed");
return -1;
}
return 0;
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}
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/* vi: set ts=4 sw=4 expandtab: */