src/thread/pthread/SDL_syssem.c
author Sam Lantinga <slouken@libsdl.org>
Sat, 04 Oct 2008 06:46:59 +0000
changeset 2765 f55c87ae336b
parent 2735 204be4fc2726
child 2859 99210400e8b9
permissions -rw-r--r--
Final merge of Google Summer of Code 2008 work...

Bring SDL to iPhone and iPod Touch
by Holmes Futrell, mentored by Sam Lantinga
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/*
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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,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    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
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    License along with this library; if not, write to the Free Software
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    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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#include <pthread.h>
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#include <semaphore.h>
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#include "SDL_thread.h"
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#include "SDL_timer.h"
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/* Wrapper around POSIX 1003.1b semaphores */
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#if defined(__MACOSX__) || defined(__IPHONEOS__)
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/* Mac OS X doesn't support sem_getvalue() as of version 10.4 */
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#include "../generic/SDL_syssem.c"
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#else
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struct SDL_semaphore
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{
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    sem_t sem;
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};
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/* Create a semaphore, initialized with value */
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SDL_sem *
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SDL_CreateSemaphore(Uint32 initial_value)
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{
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    SDL_sem *sem = (SDL_sem *) SDL_malloc(sizeof(SDL_sem));
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    if (sem) {
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        if (sem_init(&sem->sem, 0, initial_value) < 0) {
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            SDL_SetError("sem_init() failed");
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            SDL_free(sem);
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            sem = NULL;
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        }
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    } else {
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        SDL_OutOfMemory();
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    }
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    return sem;
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}
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void
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SDL_DestroySemaphore(SDL_sem * sem)
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{
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    if (sem) {
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        sem_destroy(&sem->sem);
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        SDL_free(sem);
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    }
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}
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int
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SDL_SemTryWait(SDL_sem * sem)
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{
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    int retval;
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    if (!sem) {
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        SDL_SetError("Passed a NULL semaphore");
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        return -1;
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    }
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    retval = SDL_MUTEX_TIMEDOUT;
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    if (sem_trywait(&sem->sem) == 0) {
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        retval = 0;
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    }
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    return retval;
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}
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int
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SDL_SemWait(SDL_sem * sem)
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{
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    int retval;
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    if (!sem) {
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        SDL_SetError("Passed a NULL semaphore");
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        return -1;
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    }
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    retval = sem_wait(&sem->sem);
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    if (retval < 0) {
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        SDL_SetError("sem_wait() failed");
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    }
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    return retval;
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}
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int
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SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
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{
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    int retval;
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    if (!sem) {
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        SDL_SetError("Passed a NULL semaphore");
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        return -1;
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    }
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    /* Try the easy cases first */
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    if (timeout == 0) {
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        return SDL_SemTryWait(sem);
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    }
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    if (timeout == SDL_MUTEX_MAXWAIT) {
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        return SDL_SemWait(sem);
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    }
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    /* Ack!  We have to busy wait... */
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    /* FIXME: Use sem_timedwait()? */
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    timeout += SDL_GetTicks();
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    do {
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        retval = SDL_SemTryWait(sem);
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        if (retval == 0) {
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            break;
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        }
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        SDL_Delay(1);
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    } while (SDL_GetTicks() < timeout);
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    return retval;
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}
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Uint32
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SDL_SemValue(SDL_sem * sem)
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{
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    int ret = 0;
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    if (sem) {
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        sem_getvalue(&sem->sem, &ret);
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        if (ret < 0) {
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            ret = 0;
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        }
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    }
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    return (Uint32) ret;
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}
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int
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SDL_SemPost(SDL_sem * sem)
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{
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    int retval;
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    if (!sem) {
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        SDL_SetError("Passed a NULL semaphore");
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        return -1;
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    }
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    retval = sem_post(&sem->sem);
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    if (retval < 0) {
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        SDL_SetError("sem_post() failed");
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    }
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    return retval;
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}
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#endif /* __MACOSX__ */
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/* vi: set ts=4 sw=4 expandtab: */