src/thread/nds/SDL_sysmutex.c
branchgsoc2008_nds
changeset 2670 6e4669f4db49
child 2671 c3e7c0698cbb
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/thread/nds/SDL_sysmutex.c	Tue Jun 10 06:57:57 2008 +0000
     1.3 @@ -0,0 +1,137 @@
     1.4 +/*
     1.5 +    SDL - Simple DirectMedia Layer
     1.6 +    Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
     1.7 +
     1.8 +    This library is free software; you can redistribute it and/or
     1.9 +    modify it under the terms of the GNU Library General Public
    1.10 +    License as published by the Free Software Foundation; either
    1.11 +    version 2 of the License, or (at your option) any later version.
    1.12 +
    1.13 +    This library is distributed in the hope that it will be useful,
    1.14 +    but WITHOUT ANY WARRANTY; without even the implied warranty of
    1.15 +    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    1.16 +    Library General Public License for more details.
    1.17 +
    1.18 +    You should have received a copy of the GNU Library General Public
    1.19 +    License along with this library; if not, write to the Free
    1.20 +    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    1.21 +
    1.22 +    Sam Lantinga
    1.23 +    slouken@devolution.com
    1.24 +*/
    1.25 +
    1.26 +#ifdef SAVE_RCSID
    1.27 +static char rcsid =
    1.28 + "@(#) $Id: SDL_sysmutex.c,v 1.2 2001/04/26 16:50:18 hercules Exp $";
    1.29 +#endif
    1.30 +
    1.31 +/* An implementation of mutexes using semaphores */
    1.32 +
    1.33 +#include <stdio.h>
    1.34 +#include <stdlib.h>
    1.35 +
    1.36 +#include "SDL_error.h"
    1.37 +#include "SDL_thread.h"
    1.38 +#include "SDL_systhread_c.h"
    1.39 +
    1.40 +
    1.41 +struct SDL_mutex {
    1.42 +	int recursive;
    1.43 +	Uint32 owner;
    1.44 +	SDL_sem *sem;
    1.45 +};
    1.46 +
    1.47 +/* Create a mutex */
    1.48 +SDL_mutex *SDL_CreateMutex(void)
    1.49 +{
    1.50 +	SDL_mutex *mutex;
    1.51 +
    1.52 +	/* Allocate mutex memory */
    1.53 +	mutex = (SDL_mutex *)malloc(sizeof(*mutex));
    1.54 +	if ( mutex ) {
    1.55 +		/* Create the mutex semaphore, with initial value 1 */
    1.56 +		mutex->sem = SDL_CreateSemaphore(1);
    1.57 +		mutex->recursive = 0;
    1.58 +		mutex->owner = 0;
    1.59 +		if ( ! mutex->sem ) {
    1.60 +			free(mutex);
    1.61 +			mutex = NULL;
    1.62 +		}
    1.63 +	} else {
    1.64 +		SDL_OutOfMemory();
    1.65 +	}
    1.66 +	return mutex;
    1.67 +}
    1.68 +
    1.69 +/* Free the mutex */
    1.70 +void SDL_DestroyMutex(SDL_mutex *mutex)
    1.71 +{
    1.72 +	if ( mutex ) {
    1.73 +		if ( mutex->sem ) {
    1.74 +			SDL_DestroySemaphore(mutex->sem);
    1.75 +		}
    1.76 +		free(mutex);
    1.77 +	}
    1.78 +}
    1.79 +
    1.80 +/* Lock the semaphore */
    1.81 +int SDL_mutexP(SDL_mutex *mutex)
    1.82 +{
    1.83 +#ifdef DISABLE_THREADS
    1.84 +	return 0;
    1.85 +#else
    1.86 +	Uint32 this_thread;
    1.87 +
    1.88 +	if ( mutex == NULL ) {
    1.89 +		SDL_SetError("Passed a NULL mutex");
    1.90 +		return -1;
    1.91 +	}
    1.92 +
    1.93 +	this_thread = SDL_ThreadID();
    1.94 +	if ( mutex->owner == this_thread ) {
    1.95 +		++mutex->recursive;
    1.96 +	} else {
    1.97 +		/* The order of operations is important.
    1.98 +		   We set the locking thread id after we obtain the lock
    1.99 +		   so unlocks from other threads will fail.
   1.100 +		*/
   1.101 +		SDL_SemWait(mutex->sem);
   1.102 +		mutex->owner = this_thread;
   1.103 +		mutex->recursive = 0;
   1.104 +	}
   1.105 +
   1.106 +	return 0;
   1.107 +#endif /* DISABLE_THREADS */
   1.108 +}
   1.109 +
   1.110 +/* Unlock the mutex */
   1.111 +int SDL_mutexV(SDL_mutex *mutex)
   1.112 +{
   1.113 +#ifdef DISABLE_THREADS
   1.114 +	return 0;
   1.115 +#else
   1.116 +	if ( mutex == NULL ) {
   1.117 +		SDL_SetError("Passed a NULL mutex");
   1.118 +		return -1;
   1.119 +	}
   1.120 +
   1.121 +	/* If we don't own the mutex, we can't unlock it */
   1.122 +	if ( SDL_ThreadID() != mutex->owner ) {
   1.123 +		SDL_SetError("mutex not owned by this thread");
   1.124 +		return -1;
   1.125 +	}
   1.126 +
   1.127 +	if ( mutex->recursive ) {
   1.128 +		--mutex->recursive;
   1.129 +	} else {
   1.130 +		/* The order of operations is important.
   1.131 +		   First reset the owner so another thread doesn't lock
   1.132 +		   the mutex and set the ownership before we reset it,
   1.133 +		   then release the lock semaphore.
   1.134 +		 */
   1.135 +		mutex->owner = 0;
   1.136 +		SDL_SemPost(mutex->sem);
   1.137 +	}
   1.138 +	return 0;
   1.139 +#endif /* DISABLE_THREADS */
   1.140 +}