/*

    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"

/* Semaphore functions using the OS/2 API */

#define INCL_DOS

#define INCL_DOSERRORS

#define INCL_DOSSEMAPHORES

#include <os2.h>

#include "SDL_thread.h"

#include "SDL_timer.h"

struct SDL_semaphore {

        HMTX id;

        HEV  changed;

        Uint32 value;

};

/* Create a semaphore */

DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value)

{

        SDL_sem *sem;

        ULONG ulrc;

        /* Allocate sem memory */

        sem = (SDL_sem *)SDL_malloc(sizeof(*sem));

        if ( sem ) {

                /* Create the mutex semaphore */

                ulrc = DosCreateMutexSem(NULL,&(sem->id),0,TRUE);

                if ( ulrc ) {

                        SDL_SetError("Couldn't create semaphore");

                        SDL_free(sem);

                        sem = NULL;

                } else

                {

                    DosCreateEventSem(NULL, &(sem->changed), 0, FALSE);

                    sem->value = initial_value;

                    DosReleaseMutexSem(sem->id);

                }

        } else {

                SDL_OutOfMemory();

        }

        return(sem);

}

/* Free the semaphore */

DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem)

{

        if ( sem ) {

                if ( sem->id ) {

                        DosCloseEventSem(sem->changed);

                        DosCloseMutexSem(sem->id);

                        sem->id = 0;

                }

                SDL_free(sem);

        }

}

DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout)

{

        ULONG ulrc;

        if ( ! sem ) {

                SDL_SetError("Passed a NULL sem");

                return -1;

        }

        if ( timeout == SDL_MUTEX_MAXWAIT ) {

           while (1) {

              ulrc = DosRequestMutexSem(sem->id, SEM_INDEFINITE_WAIT);

              if (ulrc) {

                 /* if error waiting mutex */

                 SDL_SetError("DosRequestMutexSem() failed");

                 return -1;

              } else if (sem->value) {

                        sem->value--;

                        DosReleaseMutexSem(sem->id);

                        return 0;

                     } else {

                        ULONG ulPostCount;

                        DosResetEventSem(sem->changed, &ulPostCount);

                        DosReleaseMutexSem(sem->id);

                        /* continue waiting until somebody posts the semaphore */

                        DosWaitEventSem(sem->changed, SEM_INDEFINITE_WAIT);

                     }

           }

        } else

        if ( timeout == 0 )

        {

            ulrc = DosRequestMutexSem(sem->id, SEM_INDEFINITE_WAIT);

            if (ulrc==NO_ERROR)

            {

                if (sem->value)

                {

                    sem->value--;

                    DosReleaseMutexSem(sem->id);

                    return 0;

                } else

                {

                    DosReleaseMutexSem(sem->id);

                    return SDL_MUTEX_TIMEDOUT;

                }

            } else

            {

                SDL_SetError("DosRequestMutexSem() failed");

                return -1;

            }

        } else {

            ulrc = DosRequestMutexSem(sem->id, SEM_INDEFINITE_WAIT);

            if (ulrc) {

               /* if error waiting mutex */

               SDL_SetError("DosRequestMutexSem() failed");

               return -1;

            } else

              if (sem->value) {

                sem->value--;

                DosReleaseMutexSem(sem->id);

                return 0;

              } else {

                ULONG ulPostCount;

                DosResetEventSem(sem->changed, &ulPostCount);

                DosReleaseMutexSem(sem->id);

                /* continue waiting until somebody posts the semaphore */

                ulrc = DosWaitEventSem(sem->changed, timeout);

                if (ulrc==NO_ERROR)

                  return 0;

                else

                  return SDL_MUTEX_TIMEDOUT;

              }

        }

        /* never reached */

        return -1;

}

DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem)

{

        return SDL_SemWaitTimeout(sem, 0);

}

DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem)

{

        return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);

}

/* Returns the current count of the semaphore */

DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem)

{

        if ( ! sem ) {

                SDL_SetError("Passed a NULL sem");

                return 0;

        }

        return sem->value;

}

DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem)

{

        if ( ! sem ) {

                SDL_SetError("Passed a NULL sem");

                return -1;

        }

        if ( DosRequestMutexSem(sem->id,SEM_INDEFINITE_WAIT) ) {

                SDL_SetError("DosRequestMutexSem() failed");

                return -1;

        }

        sem->value++;

        DosPostEventSem(sem->changed);

        DosReleaseMutexSem(sem->id);

        return 0;

}