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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/* Semaphores in the BeOS environment */
#include <be/kernel/OS.h>
#include "SDL_thread.h"
struct SDL_semaphore {
sem_id id;
};
/* Create a counting semaphore */
SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_sem *sem;
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sem = (SDL_sem *)SDL_malloc(sizeof(*sem));
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if ( sem ) {
sem->id = create_sem(initial_value, "SDL semaphore");
if ( sem->id < B_NO_ERROR ) {
SDL_SetError("create_sem() failed");
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SDL_free(sem);
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sem = NULL;
}
} else {
SDL_OutOfMemory();
}
return(sem);
}
/* Free the semaphore */
void SDL_DestroySemaphore(SDL_sem *sem)
{
if ( sem ) {
if ( sem->id >= B_NO_ERROR ) {
delete_sem(sem->id);
}
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SDL_free(sem);
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}
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
int32 val;
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
tryagain:
if ( timeout == SDL_MUTEX_MAXWAIT ) {
val = acquire_sem(sem->id);
} else {
timeout *= 1000; /* BeOS uses a timeout in microseconds */
val = acquire_sem_etc(sem->id, 1, B_RELATIVE_TIMEOUT, timeout);
}
switch (val) {
case B_INTERRUPTED:
goto tryagain;
case B_NO_ERROR:
retval = 0;
break;
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case B_TIMED_OUT:
retval = SDL_MUTEX_TIMEDOUT;
break;
case B_WOULD_BLOCK:
retval = SDL_MUTEX_TIMEDOUT;
break;
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default:
SDL_SetError("acquire_sem() 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)
{
int32 count;
Uint32 value;
value = 0;
if ( sem ) {
get_sem_count(sem->id, &count);
if ( count > 0 ) {
value = (Uint32)count;
}
}
return value;
}
/* Atomically increases the semaphore's count (not blocking) */
int SDL_SemPost(SDL_sem *sem)
{
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
if ( release_sem(sem->id) != B_NO_ERROR ) {
SDL_SetError("release_sem() failed");
return -1;
}
return 0;
}