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/*

 * Project: S.Ha.R.K.

 *

 * Coordinators:

 *   Giorgio Buttazzo    <giorgio@sssup.it>

 *   Paolo Gai           <pj@gandalf.sssup.it>

 *

 * Authors     :

 *   Paolo Gai           <pj@gandalf.sssup.it>

 *   Massimiliano Giorgi <massy@gandalf.sssup.it>

 *   Luca Abeni          <luca@gandalf.sssup.it>

 *   (see the web pages for full authors list)

 *

 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)

 *

 * http://www.sssup.it

 * http://retis.sssup.it

 * http://shark.sssup.it

 */

/**

 ------------

 CVS :        $Id: npp.c,v 1.1 2005-02-25 10:45:36 pj Exp $

 File:        $File$

 Revision:    $Revision: 1.1 $

 Last update: $Date: 2005-02-25 10:45:36 $

 ------------

 Non Preemptive Protocol. see npp.h for more details...

**/

/*

 * Copyright (C) 2000 Paolo Gai

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 */

#include <npp/npp/npp.h>

#include <ll/ll.h>

#include <arch/string.h>

#include <arch/stdio.h>

#include <kernel/const.h>

#include <sys/types.h>

#include <kernel/descr.h>

#include <kernel/var.h>

#include <kernel/func.h>

/* The NPP resource level descriptor */

typedef struct {

  mutex_resource_des m;   /*+ the mutex interface +*/

  int nlocked;  /*+ how many mutex a task currently locks +*/

} NPP_mutex_resource_des;

#if 0

/*+ print resource protocol statistics...+*/

static void NPP_resource_status(RLEVEL r)

{

  NPP_mutex_resource_des *m = (NPP_mutex_resource_des *)(resource_table[r]);

  kern_printf("%d Resources owned by the tasks %d\n", m->nlocked, exec_shadow);

}

#endif

static int NPP_res_register(RLEVEL l, PID p, RES_MODEL *r)

{

  /* NPP works with all tasks without Resource parameters */

  return -1;

}

static void NPP_res_detach(RLEVEL l, PID p)

{

  NPP_mutex_resource_des *m = (NPP_mutex_resource_des *)(resource_table[l]);

  if (m->nlocked)

    kern_raise(XMUTEX_OWNER_KILLED, p);

}

static int NPP_init(RLEVEL l, mutex_t *m, const mutexattr_t *a)

{

  if (a->mclass != NPP_MCLASS)

    return -1;

  m->mutexlevel = l;

  m->opt = (void *)NIL;

  return 0;

}

static int NPP_destroy(RLEVEL l, mutex_t *m)

{

//  NPP_mutex_resource_des *lev = (NPP_mutex_resource_des *)(resource_table[l]);

  if ( ((PID) m->opt) != NIL)

    return (EBUSY);

  return 0;

}

static int NPP_lock(RLEVEL l, mutex_t *m)

{

  NPP_mutex_resource_des *lev;

  SYS_FLAGS f;

  f = kern_fsave();

  if (((PID)m->opt) == exec_shadow) {

    /* the task already owns the mutex */

    kern_frestore(f);

    return (EDEADLK);

  }

  /* p->opt == NIL (It can't be the case of p->opt != NIL and != exec_shadow

     because when a task lock a mutex it become unpreemptable */

  /* the mutex is free, We can lock it! */

  lev = (NPP_mutex_resource_des *)(resource_table[l]);

  if (!lev->nlocked) task_nopreempt();

  lev->nlocked++;

  m->opt = (void *)exec_shadow;

  kern_frestore(f);

  return 0;

}

// static int NPP_trylock(RLEVEL l, mutex_t *m) is a non-sense!

static int NPP_unlock(RLEVEL l, mutex_t *m)

{

  NPP_mutex_resource_des *lev;

  /* the mutex is mine */

  lev = (NPP_mutex_resource_des *)(resource_table[l]);

  lev->nlocked--;

  m->opt = (void *)NIL;

  if (!lev->nlocked) task_preempt();

  return 0;

}

void NPP_register_module(void)

{

  RLEVEL l;                  /* the level that we register */

  NPP_mutex_resource_des *m;  /* for readableness only */

  printk("NPP_register_module\n");

  /* request an entry in the level_table */

  l = resource_alloc_descriptor();

  /* alloc the space needed for the EDF_level_des */

  m = (NPP_mutex_resource_des *)kern_alloc(sizeof(NPP_mutex_resource_des));

  /* update the level_table with the new entry */

  resource_table[l] = (resource_des *)m;

  /* fill the resource_des descriptor */

  m->m.r.rtype                       = MUTEX_RTYPE;

  m->m.r.res_register                = NPP_res_register;

  m->m.r.res_detach                  = NPP_res_detach;

  /* fill the mutex_resource_des descriptor */

  m->m.init                          = NPP_init;

  m->m.destroy                       = NPP_destroy;

  m->m.lock                          = NPP_lock;

  m->m.trylock                       = NPP_lock;   // !!!!!!!!!!!!

  m->m.unlock                        = NPP_unlock;

  /* fill the NPP_mutex_resource_des descriptor */

  m->nlocked = 0;

}