/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 of the License, or (at your option) any later version.

    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

    Lesser General Public License for more details.

    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

    Sam Lantinga

    slouken@libsdl.org

*/

#include "SDL_config.h"

/* System independent thread management routines for SDL */

#include "SDL_mutex.h"

#include "SDL_thread.h"

#include "SDL_thread_c.h"

#include "SDL_systhread.h"

#define ARRAY_CHUNKSIZE	32

/* The array of threads currently active in the application

   (except the main thread)

   The manipulation of an array here is safer than using a linked list.

*/

static int SDL_maxthreads = 0;

static int SDL_numthreads = 0;

static SDL_Thread **SDL_Threads = NULL;

static SDL_mutex *thread_lock = NULL;

int SDL_ThreadsInit(void)

{

	int retval;

	retval = 0;

	thread_lock = SDL_CreateMutex();

	if ( thread_lock == NULL ) {

		retval = -1;

	}

	return(retval);

}

/* This should never be called...

   If this is called by SDL_Quit(), we don't know whether or not we should

   clean up threads here.  If any threads are still running after this call,

   they will no longer have access to any per-thread data.

 */

void SDL_ThreadsQuit(void)

{

	SDL_mutex *mutex;

	mutex = thread_lock;

	thread_lock = NULL;

	if ( mutex != NULL ) {

		SDL_DestroyMutex(mutex);

	}

}

/* Routines for manipulating the thread list */

static void SDL_AddThread(SDL_Thread *thread)

{

	/* WARNING:

	   If the very first threads are created simultaneously, then

	   there could be a race condition causing memory corruption.

	   In practice, this isn't a problem because by definition there

	   is only one thread running the first time this is called.

	*/

	if ( !thread_lock ) {

		if ( SDL_ThreadsInit() < 0 ) {

			return;

		}

	}

	SDL_mutexP(thread_lock);

	/* Expand the list of threads, if necessary */

#ifdef DEBUG_THREADS

	printf("Adding thread (%d already - %d max)\n",

			SDL_numthreads, SDL_maxthreads);

#endif

	if ( SDL_numthreads == SDL_maxthreads ) {

		SDL_Thread **threads;

		threads = (SDL_Thread **)SDL_realloc(SDL_Threads,

			(SDL_maxthreads+ARRAY_CHUNKSIZE)*(sizeof *threads));

		if ( threads == NULL ) {

			SDL_OutOfMemory();

			goto done;

		}

		SDL_maxthreads += ARRAY_CHUNKSIZE;

		SDL_Threads = threads;

	}

	SDL_Threads[SDL_numthreads++] = thread;

done:

	SDL_mutexV(thread_lock);

}

static void SDL_DelThread(SDL_Thread *thread)

{

	int i;

	if ( !thread_lock ) {

		return;

	}

	SDL_mutexP(thread_lock);

	for ( i=0; i<SDL_numthreads; ++i ) {

		if ( thread == SDL_Threads[i] ) {

			break;

		}

	}

	if ( i < SDL_numthreads ) {

		if ( --SDL_numthreads > 0 ) {

			while ( i < SDL_numthreads ) {

				SDL_Threads[i] = SDL_Threads[i+1];

				++i;

			}

		} else {

			SDL_maxthreads = 0;

			SDL_free(SDL_Threads);

			SDL_Threads = NULL;

		}

#ifdef DEBUG_THREADS

		printf("Deleting thread (%d left - %d max)\n",

				SDL_numthreads, SDL_maxthreads);

#endif

	}

	SDL_mutexV(thread_lock);

	if ( SDL_Threads == NULL ) {

		SDL_ThreadsQuit();

	}

}

/* The default (non-thread-safe) global error variable */

static SDL_error SDL_global_error;

/* Routine to get the thread-specific error variable */

SDL_error *SDL_GetErrBuf(void)

{

	SDL_error *errbuf;

	errbuf = &SDL_global_error;

	if ( SDL_Threads ) {

		int i;

		Uint32 this_thread;

		this_thread = SDL_ThreadID();

		SDL_mutexP(thread_lock);

		for ( i=0; i<SDL_numthreads; ++i ) {

			if ( this_thread == SDL_Threads[i]->threadid ) {

				errbuf = &SDL_Threads[i]->errbuf;

				break;

			}

		}

		SDL_mutexV(thread_lock);

	}

	return(errbuf);

}

/* Arguments and callback to setup and run the user thread function */

typedef struct {

	int (SDLCALL *func)(void *);

	void *data;

	SDL_Thread *info;

	SDL_sem *wait;

} thread_args;

void SDL_RunThread(void *data)

{

	thread_args *args;

	int (SDLCALL *userfunc)(void *);

	void *userdata;

	int *statusloc;

	/* Perform any system-dependent setup

	   - this function cannot fail, and cannot use SDL_SetError()

	 */

	SDL_SYS_SetupThread();

	/* Get the thread id */

	args = (thread_args *)data;

	args->info->threadid = SDL_ThreadID();

	/* Figure out what function to run */

	userfunc = args->func;

	userdata = args->data;

	statusloc = &args->info->status;

	/* Wake up the parent thread */

	SDL_SemPost(args->wait);

	/* Run the function */

	*statusloc = userfunc(userdata);

}

#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD

#undef SDL_CreateThread

DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread)

#else

DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(int (SDLCALL *fn)(void *), void *data)

#endif

{

	SDL_Thread *thread;

	thread_args *args;

	int ret;

	/* Allocate memory for the thread info structure */

	thread = (SDL_Thread *)SDL_malloc(sizeof(*thread));

	if ( thread == NULL ) {

		SDL_OutOfMemory();

		return(NULL);

	}

	SDL_memset(thread, 0, (sizeof *thread));

	thread->status = -1;

	/* Set up the arguments for the thread */

	args = (thread_args *)SDL_malloc(sizeof(*args));

	if ( args == NULL ) {

		SDL_OutOfMemory();

		SDL_free(thread);

		return(NULL);

	}

	args->func = fn;

	args->data = data;

	args->info = thread;

	args->wait = SDL_CreateSemaphore(0);

	if ( args->wait == NULL ) {

		SDL_free(thread);

		SDL_free(args);

		return(NULL);

	}

	/* Add the thread to the list of available threads */

	SDL_AddThread(thread);

	/* Create the thread and go! */

#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD

	ret = SDL_SYS_CreateThread(thread, args, pfnBeginThread, pfnEndThread);

#else

	ret = SDL_SYS_CreateThread(thread, args);

#endif

	if ( ret >= 0 ) {

		/* Wait for the thread function to use arguments */

		SDL_SemWait(args->wait);

	} else {

		/* Oops, failed.  Gotta free everything */

		SDL_DelThread(thread);

		SDL_free(thread);

		thread = NULL;

	}

	SDL_DestroySemaphore(args->wait);

	SDL_free(args);

	/* Everything is running now */

	return(thread);

}

void SDL_WaitThread(SDL_Thread *thread, int *status)

{

	if ( thread ) {

		SDL_SYS_WaitThread(thread);

		if ( status ) {

			*status = thread->status;

		}

		SDL_DelThread(thread);

		SDL_free(thread);

	}

}

Uint32 SDL_GetThreadID(SDL_Thread *thread)

{

	Uint32 id;

	if ( thread ) {

		id = thread->threadid;

	} else {

		id = SDL_ThreadID();

	}

	return(id);

}

void SDL_KillThread(SDL_Thread *thread)

{

	if ( thread ) {

		SDL_SYS_KillThread(thread);

		SDL_WaitThread(thread, NULL);

	}

}