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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: rr.h,v 1.1 2005-02-25 10:45:58 pj Exp $

 File:        $File$
 Revision:    $Revision: 1.1 $
 Last update: $Date: 2005-02-25 10:45:58 $

 This file contains the scheduling module RR (Round Robin)

   RR (Round Robin)

 Task Models Accepted:
   NRT_TASK_MODEL - Non-Realtime Tasks
     weight field is ignored
     slice  field is used to set the slice of a task, if it is !=0
     activation field is ignored
     policy field is ignored
     inherit field is ignored

   This module schedule his tasks following the classic round-robin
   scheme. The default timeslice is given at registration time and is a
   a per-task specification. The default timeslice is used if the slice
   field in the NRT_TASK_MODEL is 0.

   The module always SKIP instances, either if SAVE_ARRIVALS is set!!!
   There is another module, RR2, thar remember activations...

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

 Restrictions & special features:
   - if specified, it creates at init time a task,
     called "Main", attached to the function __init__().
   - There must be only one module in the system that creates a task
     attached to the function __init__().
   - The level tries to guarantee that a task uses a "full" timeslice
     before going to the queue tail. "full" means that a task can execute
     a maximum time of slice+sys_tick due to the approx. done by
     the Virtual Machine. If a task execute more time than the slice,
     the next time it execute less...


 * 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 __RR_H__
#define __RR_H__

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


extern TASK __init__(void *arg);

/*+ Const: +*/
#define RR_MINIMUM_SLICE      1000 /*+ Minimum Timeslice +*/
#define RR_MAXIMUM_SLICE    500000 /*+ Maximum Timeslice +*/

#define RR_MAIN_YES              1 /*+ The level creates the main +*/
#define RR_MAIN_NO               0 /*+ The level does'nt create the main +*/

/*+ Registration function:
    TIME slice                the slice for the Round Robin queue
    int createmain            1 if the level creates the main task 0 otherwise
    struct multiboot_info *mb used if createmain specified  

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

LEVEL RR_register_level(TIME slice,
                       int createmain,
                       struct multiboot_info *mb);