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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
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slouken@libsdl.org
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*/
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#include "SDL_config.h"
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/* An implementation of semaphores using mutexes and condition variables */
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#include "SDL_thread.h"
#include "SDL_systhread_c.h"
struct SDL_semaphore
{
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struct SignalSemaphore Sem;
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};
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#define D(x)
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SDL_sem *
SDL_CreateSemaphore (Uint32 initial_value)
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sem = (SDL_sem *) SDL_malloc (sizeof (*sem));
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if (!sem) {
SDL_OutOfMemory ();
return (0);
}
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D (bug ("Creating semaphore %lx...\n", sem));
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SDL_memset (sem, 0, sizeof (*sem));
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InitSemaphore (&sem->Sem);
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}
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void
SDL_DestroySemaphore (SDL_sem * sem)
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D (bug ("Destroying semaphore %lx...\n", sem));
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// Condizioni per liberare i task in attesa?
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SDL_free (sem);
}
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}
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int
SDL_SemTryWait (SDL_sem * sem)
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if (!sem) {
SDL_SetError ("Passed a NULL semaphore");
return -1;
}
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D (bug ("TryWait semaphore...%lx\n", sem));
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ObtainSemaphore (&sem->Sem);
// ReleaseSemaphore(&sem->Sem);
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}
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int
SDL_SemWaitTimeout (SDL_sem * sem, Uint32 timeout)
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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;
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}
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int
SDL_SemWait (SDL_sem * sem)
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{
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ObtainSemaphore (&sem->Sem);
return 0;
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}
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Uint32
SDL_SemValue (SDL_sem * sem)
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{
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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;
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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 semaphore");
return -1;
}
D (bug ("SemPost semaphore...%lx\n", sem));
ReleaseSemaphore (&sem->Sem);
return 0;
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}
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/* vi: set ts=4 sw=4 expandtab: */