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
*/
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/* RISC OS semiphores based on linux code */
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#include <stdlib.h>
#include "SDL_error.h"
#include "SDL_timer.h"
#include "SDL_thread.h"
#include "SDL_systhread_c.h"
#ifdef DISABLE_THREADS
SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
SDL_SetError("SDL not configured with thread support");
return (SDL_sem *)0;
}
void SDL_DestroySemaphore(SDL_sem *sem)
{
return;
}
int SDL_SemTryWait(SDL_sem *sem)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
int SDL_SemWait(SDL_sem *sem)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
Uint32 SDL_SemValue(SDL_sem *sem)
{
return 0;
}
int SDL_SemPost(SDL_sem *sem)
{
SDL_SetError("SDL not configured with thread support");
return -1;
}
#else
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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h> /* For getpid() */
#include <pthread.h>
#include <semaphore.h>
struct SDL_semaphore {
sem_t *sem;
sem_t sem_data;
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/* Create a semaphore, initialized with value */
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SDL_sem *SDL_CreateSemaphore(Uint32 initial_value)
{
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SDL_sem *sem = (SDL_sem *) malloc(sizeof(SDL_sem));
if ( sem ) {
if ( sem_init(&sem->sem_data, 0, initial_value) < 0 ) {
SDL_SetError("sem_init() failed");
free(sem);
sem = NULL;
} else {
sem->sem = &sem->sem_data;
}
} else {
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SDL_OutOfMemory();
}
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return sem;
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}
void SDL_DestroySemaphore(SDL_sem *sem)
{
if ( sem ) {
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sem_destroy(sem->sem);
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free(sem);
}
}
int SDL_SemTryWait(SDL_sem *sem)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
retval = SDL_MUTEX_TIMEDOUT;
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if ( sem_trywait(sem->sem) == 0 ) {
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retval = 0;
}
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return retval;
}
int SDL_SemWait(SDL_sem *sem)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
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retval = sem_wait(sem->sem);
if ( retval < 0 ) {
SDL_SetError("sem_wait() failed");
}
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return retval;
}
int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)
{
int retval;
if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
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/* Try the easy cases first */
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if ( timeout == 0 ) {
return SDL_SemTryWait(sem);
}
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if ( timeout == SDL_MUTEX_MAXWAIT ) {
return SDL_SemWait(sem);
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/* Ack! We have to busy wait... */
timeout += SDL_GetTicks();
do {
retval = SDL_SemTryWait(sem);
if ( retval == 0 ) {
break;
}
SDL_Delay(1);
} while ( SDL_GetTicks() < timeout );
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return retval;
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}
Uint32 SDL_SemValue(SDL_sem *sem)
{
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int ret = 0;
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if ( sem ) {
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sem_getvalue(sem->sem, &ret);
if ( ret < 0 ) {
ret = 0;
}
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return (Uint32)ret;
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}
int SDL_SemPost(SDL_sem *sem)
{
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int retval;
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if ( ! sem ) {
SDL_SetError("Passed a NULL semaphore");
return -1;
}
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retval = sem_post(sem->sem);
if ( retval < 0 ) {
SDL_SetError("sem_post() failed");
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return retval;
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}
#endif /* DISABLE_THREADS */