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 * Project: S.Ha.R.K.
 * Coordinators:
 *   Giorgio Buttazzo    <>
 *   Paolo Gai           <>
 * Authors     :
 *   Paolo Gai           <>
 *   Massimiliano Giorgi <>
 *   Luca Abeni          <>
 *   (see the web pages for full authors list)
 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)

 CVS :        $Id: ds.h,v 1.1 2005-02-25 10:53:02 pj Exp $

 File:        $File$
 Revision:    $Revision: 1.1 $
 Last update: $Date: 2005-02-25 10:53:02 $

 This file contains the aperiodic server DS (Polling Server)

   DS (Deferrable Server)

 Task Models Accepted:
   SOFT_TASK_MODEL - Soft Tasks
     wcet field is ignored
     met field is ignored
     period field is ignored
     periodicity field can be only APERIODIC
     arrivals field can be either SAVE or SKIP

   This module schedule his tasks following the Deferrable Server scheme.

   All the tasks are put in a FIFO (FCFS) queue and at a time only the first
   task in the queue is put in the upper level.

   The module remembers pending activations when calling task_sleep...

 Exceptions raised:
     This level doesn't support guests. When a guest operation
     is called, the exception is raised.

 Restrictions & special features:
   - This level doesn't manage the main task.
   - At init time we have to specify:
     . The Capacity and the period used by the server
   - The level don't use the priority field.
   - A function to return the used bandwidth of the level is provided.
   - if an aperiodic task calls a task_delay when owning a mutex implemented
     with shadows, the delay may have no effect, so don't use delay when
     using a mutex!!!


 * 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
 * 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

#ifndef __DS_H__
#define __DS_H__

#include <kernel/config.h>
#include <sys/types.h>
#include <kernel/types.h>
#include "ll/sys/cdefs.h"


/*+ 1 - ln(2) +*/
#define RM_MINFREEBANDWIDTH 1317922825

/*+ flags... +*/
#define DS_DISABLE_ALL           0
#define DS_ENABLE_BACKGROUND     1  /*+ Background scheduling enabled +*/
#define DS_ENABLE_GUARANTEE_EDF  2  /*+ Task Guarantee enabled +*/
#define DS_ENABLE_ALL_EDF        3  /*+ All flags enabled      +*/

#define DS_ENABLE_GUARANTEE_RM   4  /*+ Task Guarantee enabled +*/
#define DS_ENABLE_ALL_RM         5  /*+ All flags enabled      +*/

/*+ internal flags +*/
#define DS_BACKGROUND            8  /*+ this flag is set when scheduling
                                        in background +*/
#define DS_BACKGROUND_BLOCK     16  /*+ this flag is set when we want to
                                        blocks the background scheduling +*/

/*+ Registration function:
    bandwidth_t b Max bandwidth used by the TBS
    int flags     Options to be used in this level instance...
    LEVEL master  the level that must be used as master level for the
                  TBS tasks
    int num,den   used to compute the TBS bandwidth

    returns the level number at which the module has been registered.

LEVEL DS_register_level(int flags, LEVEL master, int Cs, int per);

/*+ Returns the used bandwidth of a level +*/
bandwidth_t DS_usedbandwidth(LEVEL l);