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/*
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 * Project: S.Ha.R.K.
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 *
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 * Coordinators:
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 *   Giorgio Buttazzo    <giorgio@sssup.it>
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 *   Paolo Gai           <pj@gandalf.sssup.it>
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 *
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 * Authors     :
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 *   Paolo Gai           <pj@gandalf.sssup.it>
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 *   Massimiliano Giorgi <massy@gandalf.sssup.it>
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 *   Luca Abeni          <luca@gandalf.sssup.it>
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 *   (see the web pages for full authors list)
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 *
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 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
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 *
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 * http://www.sssup.it
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 * http://retis.sssup.it
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 * http://shark.sssup.it
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 */
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/**
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 ------------
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 CVS :        $Id: npp.c,v 1.1 2005-02-25 10:45:36 pj Exp $
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 File:        $File$
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 Revision:    $Revision: 1.1 $
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 Last update: $Date: 2005-02-25 10:45:36 $
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 ------------
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 Non Preemptive Protocol. see npp.h for more details...
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**/
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/*
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 * Copyright (C) 2000 Paolo Gai
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 *
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 */
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#include <npp/npp/npp.h>
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#include <ll/ll.h>
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#include <ll/string.h>
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#include <ll/stdio.h>
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#include <kernel/const.h>
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#include <sys/types.h>
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#include <kernel/descr.h>
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#include <kernel/var.h>
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#include <kernel/func.h>
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/* The NPP resource level descriptor */
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typedef struct {
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  mutex_resource_des m;   /*+ the mutex interface +*/
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  int nlocked;  /*+ how many mutex a task currently locks +*/
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} NPP_mutex_resource_des;
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#if 0
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/*+ print resource protocol statistics...+*/
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static void NPP_resource_status(RLEVEL r)
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{
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  NPP_mutex_resource_des *m = (NPP_mutex_resource_des *)(resource_table[r]);
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  kern_printf("%d Resources owned by the tasks %d\n", m->nlocked, exec_shadow);
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}
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#endif
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static int NPP_res_register(RLEVEL l, PID p, RES_MODEL *r)
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{
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  /* NPP works with all tasks without Resource parameters */
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  return -1;
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}
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static void NPP_res_detach(RLEVEL l, PID p)
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{
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  NPP_mutex_resource_des *m = (NPP_mutex_resource_des *)(resource_table[l]);
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  if (m->nlocked)
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    kern_raise(XMUTEX_OWNER_KILLED, p);
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}
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static int NPP_init(RLEVEL l, mutex_t *m, const mutexattr_t *a)
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{
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  if (a->mclass != NPP_MCLASS)
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    return -1;
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  m->mutexlevel = l;
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  m->opt = (void *)NIL;
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  return 0;
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}
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static int NPP_destroy(RLEVEL l, mutex_t *m)
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{
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//  NPP_mutex_resource_des *lev = (NPP_mutex_resource_des *)(resource_table[l]);
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  if ( ((PID) m->opt) != NIL)
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    return (EBUSY);
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  return 0;
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}
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static int NPP_lock(RLEVEL l, mutex_t *m)
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{
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  NPP_mutex_resource_des *lev;
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  SYS_FLAGS f;
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  f = kern_fsave();
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  if (((PID)m->opt) == exec_shadow) {
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    /* the task already owns the mutex */
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    kern_frestore(f);
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    return (EDEADLK);
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  }
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  /* p->opt == NIL (It can't be the case of p->opt != NIL and != exec_shadow
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     because when a task lock a mutex it become unpreemptable */
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  /* the mutex is free, We can lock it! */
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  lev = (NPP_mutex_resource_des *)(resource_table[l]);
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  if (!lev->nlocked) task_nopreempt();
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  lev->nlocked++;
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  m->opt = (void *)exec_shadow;
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  kern_frestore(f);
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  return 0;
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}
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// static int NPP_trylock(RLEVEL l, mutex_t *m) is a non-sense!
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static int NPP_unlock(RLEVEL l, mutex_t *m)
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{
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  NPP_mutex_resource_des *lev;
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  /* the mutex is mine */
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  lev = (NPP_mutex_resource_des *)(resource_table[l]);
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  lev->nlocked--;
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  m->opt = (void *)NIL;
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  if (!lev->nlocked) task_preempt();
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  return 0;
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}
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void NPP_register_module(void)
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{
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  RLEVEL l;                  /* the level that we register */
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  NPP_mutex_resource_des *m;  /* for readableness only */
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  printk("NPP_register_module\n");
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  /* request an entry in the level_table */
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  l = resource_alloc_descriptor();
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  /* alloc the space needed for the EDF_level_des */
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  m = (NPP_mutex_resource_des *)kern_alloc(sizeof(NPP_mutex_resource_des));
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  /* update the level_table with the new entry */
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  resource_table[l] = (resource_des *)m;
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  /* fill the resource_des descriptor */
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  m->m.r.rtype                       = MUTEX_RTYPE;
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  m->m.r.res_register                = NPP_res_register;
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  m->m.r.res_detach                  = NPP_res_detach;
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  /* fill the mutex_resource_des descriptor */
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  m->m.init                          = NPP_init;
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  m->m.destroy                       = NPP_destroy;
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  m->m.lock                          = NPP_lock;
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  m->m.trylock                       = NPP_lock;   // !!!!!!!!!!!!
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  m->m.unlock                        = NPP_unlock;
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  /* fill the NPP_mutex_resource_des descriptor */
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  m->nlocked = 0;
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}
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