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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: nop.c,v 1.1 2005-02-25 10:40:58 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 10:40:58 $
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 ------------
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 Binary Semaphores. see nop.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 <nop/nop/nop.h>
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#include <ll/ll.h>
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#include <ll/stdio.h>
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#include <ll/string.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 NOP resource level descriptor */
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typedef struct {
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  mutex_resource_des m;   /*+ the mutex interface +*/
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} NOP_mutex_resource_des;
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/* this is the structure normally pointed by the opt field in the
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   mutex_t structure */
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typedef struct {
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  PID owner;
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  IQUEUE blocked;
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} NOP_mutex_t;
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/* Wait status for this library */
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#define NOP_WAIT LIB_STATUS_BASE
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static int NOP_res_register(RLEVEL l, PID p, RES_MODEL *r)
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{
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  return -1;
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}
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static void NOP_res_detach(RLEVEL l, PID p)
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{
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}
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static int NOP_init(RLEVEL l, mutex_t *m, const mutexattr_t *a)
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{
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  NOP_mutex_t *p;
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  if (a->mclass != NOP_MCLASS)
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    return -1;
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  p = (NOP_mutex_t *) kern_alloc(sizeof(NOP_mutex_t));
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  /* control if there is enough memory; no control on init on a
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     non- destroyed mutex */
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  if (!p)
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    return (ENOMEM);
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  p->owner = NIL;
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  iq_init(&p->blocked, &freedesc, 0);
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  m->mutexlevel = l;
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  m->opt = (void *)p;
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  return 0;
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}
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static int NOP_destroy(RLEVEL l, mutex_t *m)
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{
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//  NOP_mutex_resource_des *lev = (NOP_mutex_resource_des *)(resource_table[l]);
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  SYS_FLAGS f;
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  if ( ((NOP_mutex_t *)m->opt)->owner != NIL)
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    return (EBUSY);
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  f = kern_fsave();
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  if (m->opt) {
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    kern_free(m->opt,sizeof(NOP_mutex_t));
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    m->opt = NULL;
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  }
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  kern_frestore(f);
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  return 0;
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}
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static int NOP_lock(RLEVEL l, mutex_t *m)
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{
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  NOP_mutex_t *p;
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  SYS_FLAGS f;
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  f = kern_fsave();
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  p = (NOP_mutex_t *)m->opt;
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  if (!p) {
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    /* if the mutex is not initialized, initialize it! */
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    NOP_mutexattr_t a;
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    NOP_mutexattr_default(a);
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    NOP_init(l, m, &a);
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  }
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  if (p->owner == 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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  if (p->owner != NIL)  {           /* We must block exec task   */
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       LEVEL l;            /* for readableness only */
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       proc_table[exec_shadow].context = kern_context_save();
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       kern_epilogue_macro();
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       l = proc_table[exec_shadow].task_level;
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       level_table[l]->public_block(l,exec_shadow);
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       /* we insert the task in the semaphore queue */
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       proc_table[exec_shadow].status = NOP_WAIT;
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       iq_insertlast(exec_shadow,&p->blocked);
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       /* and finally we reschedule */
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       exec = exec_shadow = -1;
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       scheduler();
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       kern_context_load(proc_table[exec_shadow].context);
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  }
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  else {
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    /* the mutex is free, We can lock it! */
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    p->owner = exec_shadow;
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    kern_frestore(f);
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  }
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  return 0;
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}
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static int NOP_trylock(RLEVEL l, mutex_t *m)
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{
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  NOP_mutex_t *p;
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  SYS_FLAGS f;
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  f = kern_fsave();
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  p = (NOP_mutex_t *)m->opt;
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  if (!p) {
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    /* if the mutex is not initialized, initialize it! */
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    NOP_mutexattr_t a;
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    NOP_mutexattr_default(a);
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    NOP_init(l, m, &a);
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  }
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  if (p->owner != NIL)  {
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    /* a task already owns the mutex */
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    kern_frestore(f);
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    return (EBUSY);
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  }
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  else {
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    /* the mutex is free, We can lock it! */
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    p->owner = exec_shadow;
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    kern_frestore(f);
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  }
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  return 0;
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}
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static int NOP_unlock(RLEVEL l, mutex_t *m)
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{
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  NOP_mutex_t *p;
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  p = (NOP_mutex_t *)m->opt;
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  if (!p)
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    return (EINVAL);
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  if (p->owner != exec_shadow) {
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    /* the mutex is owned by another task!!! */
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    kern_sti();
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    return (EPERM);
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  }
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  proc_table[exec_shadow].context = kern_context_save();
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  /* the mutex is mine, pop the firsttask to extract */
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  p->owner = iq_getfirst(&p->blocked);
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  if (p->owner != NIL) {
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    l = proc_table[p->owner].task_level;
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    level_table[l]->public_unblock(l,p->owner);
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  }
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  scheduler();
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  kern_context_load(proc_table[exec_shadow].context);
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  return 0;
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}
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RLEVEL NOP_register_module(void)
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{
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  RLEVEL l;                  /* the level that we register */
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  NOP_mutex_resource_des *m;  /* for readableness only */
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  printk("NOP_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 = (NOP_mutex_resource_des *)kern_alloc(sizeof(NOP_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                = NOP_res_register;
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  m->m.r.res_detach                  = NOP_res_detach;
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  /* fill the mutex_resource_des descriptor */
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  m->m.init                          = NOP_init;
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  m->m.destroy                       = NOP_destroy;
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  m->m.lock                          = NOP_lock;
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  m->m.trylock                       = NOP_trylock;
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  m->m.unlock                        = NOP_unlock;
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  return l;
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}
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