/*

SDL - Simple DirectMedia Layer

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

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

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

*/

/* 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 struct SignalSemaphore thread_lock;

int thread_lock_created = 0;

int SDL_ThreadsInit(void)

{

InitSemaphore(&thread_lock);

thread_lock_created=1;

return 0;

}

/* 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()

{

thread_lock_created=0;

}

/* Routines for manipulating the thread list */

static void SDL_AddThread(SDL_Thread *thread)

{

SDL_Thread **threads;

/* 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_created ) {

if ( SDL_ThreadsInit() < 0 ) {

return;

}

}

ObtainSemaphore(&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 ) {

(sizeof *threads));

if ( threads == NULL ) {

SDL_OutOfMemory();

goto done;

}

SDL_maxthreads += ARRAY_CHUNKSIZE;

if ( SDL_Threads ) {

}

SDL_Threads = threads;

}

SDL_Threads[SDL_numthreads++] = thread;

done:

ReleaseSemaphore(&thread_lock);

}

static void SDL_DelThread(SDL_Thread *thread)

{

int i;

if ( thread_lock_created ) {

ObtainSemaphore(&thread_lock);

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

if ( thread == SDL_Threads[i] ) {

break;

}

}

if ( i < SDL_numthreads ) {

--SDL_numthreads;

while ( i < SDL_numthreads ) {

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

++i;

}

#ifdef DEBUG_THREADS

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

SDL_numthreads, SDL_maxthreads);

#endif

}

ReleaseSemaphore(&thread_lock);

}

}

/* 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();

ObtainSemaphore(&thread_lock);

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

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

errbuf = &SDL_Threads[i]->errbuf;

break;

}

}

ReleaseSemaphore(&thread_lock);

}

return(errbuf);

}

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

typedef struct {

int (*func)(void *);

void *data;

SDL_Thread *info;

struct Task *wait;

} thread_args;

void SDL_RunThread(void *data)

{

thread_args *args;

int (*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 */

Signal(args->wait,SIGBREAKF_CTRL_E);

/* Run the function */

*statusloc = userfunc(userdata);

}

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

{

SDL_Thread *thread;

thread_args *args;

int ret;

/* Allocate memory for the thread info structure */

if ( thread == NULL ) {

SDL_OutOfMemory();

return(NULL);

}

thread->status = -1;

/* Set up the arguments for the thread */

if ( args == NULL ) {

SDL_OutOfMemory();

return(NULL);

}

args->func = fn;

args->data = data;

args->info = thread;

args->wait = FindTask(NULL);

if ( args->wait == NULL ) {

SDL_free(thread);

SDL_free(args);

SDL_OutOfMemory();

return(NULL);

}

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

SDL_AddThread(thread);

D(bug("Starting thread...\n"));

/* Create the thread and go! */

ret = SDL_SYS_CreateThread(thread, args);

if ( ret >= 0 ) {

D(bug("Waiting for thread CTRL_E...\n"));

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

Wait(SIGBREAKF_CTRL_E);

D(bug(" Arrived."));

} else {

/* Oops, failed. Gotta free everything */

SDL_DelThread(thread);

thread = NULL;

}

/* 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);

}

}

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);

}

}