/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2012 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"

/* Rockbox mutex wrapper */

#include "SDL_thread.h"
#include "SDL_systhread_c.h"


struct SDL_mutex {
    int recursive;
    Uint32 owner;
    struct mutex m;
};

/* Create a mutex */
SDL_mutex *SDL_CreateMutex(void)
{
    SDL_mutex *mutex;

    /* Allocate mutex memory */
    mutex = (SDL_mutex *)SDL_malloc(sizeof(*mutex));
    if ( mutex ) {
        rb->mutex_init(&mutex->m);
        mutex->recursive = 0;
        mutex->owner = 0;
    } else {
        SDL_OutOfMemory();
    }
    return mutex;
}

/* Free the mutex */
void SDL_DestroyMutex(SDL_mutex *mutex)
{
    if ( mutex ) {
        SDL_free(mutex);
    }
}

int SDL_mutexP(SDL_mutex *mutex)
{
#if SDL_THREADS_DISABLED
    return 0;
#else
    Uint32 this_thread;

    if ( mutex == NULL ) {
        SDL_SetError("Passed a NULL mutex");
        return -1;
    }

    this_thread = SDL_ThreadID();
    if ( mutex->owner == this_thread ) {
        ++mutex->recursive;
    } else {
        /* The order of operations is important.
           We set the locking thread id after we obtain the lock
           so unlocks from other threads will fail.
        */
        rb->mutex_lock(&mutex->m);
        mutex->owner = this_thread;
        mutex->recursive = 0;
    }

    return 0;
#endif /* SDL_THREADS_DISABLED */
}

/* Unlock the mutex */
int SDL_mutexV(SDL_mutex *mutex)
{
#if SDL_THREADS_DISABLED
    return 0;
#else
    if ( mutex == NULL ) {
        SDL_SetError("Passed a NULL mutex");
        return -1;
    }

    /* If we don't own the mutex, we can't unlock it */
    if ( SDL_ThreadID() != mutex->owner ) {
        SDL_SetError("mutex not owned by this thread");
        return -1;
    }

    if ( mutex->recursive ) {
        --mutex->recursive;
    } else {
        /* The order of operations is important.
           First reset the owner so another thread doesn't lock
           the mutex and set the ownership before we reset it,
           then release the lock semaphore.
        */
        mutex->owner = 0;
        rb->mutex_unlock(&mutex->m);
    }
    return 0;
#endif /* SDL_THREADS_DISABLED */
}