/*
    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 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) {
        threads =
            (SDL_Thread **) SDL_malloc ((SDL_maxthreads + ARRAY_CHUNKSIZE) *
                                        (sizeof *threads));
        if (threads == NULL) {
            SDL_OutOfMemory ();
            goto done;
        }
        SDL_memcpy (threads, SDL_Threads, SDL_numthreads * (sizeof *threads));
        SDL_maxthreads += ARRAY_CHUNKSIZE;
        if (SDL_Threads) {
            SDL_free (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 */
    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 = 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);
        SDL_free (thread);
        thread = NULL;
    }
    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);
    }
}

/* vi: set ts=4 sw=4 expandtab: */