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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: posix.c,v 1.4 2003-01-07 17:07:50 pj Exp $

 File:        $File$

 Revision:    $Revision: 1.4 $

 Last update: $Date: 2003-01-07 17:07:50 $

 ------------

 This file contains the scheduling module compatible with POSIX

 specifications

 Read posix.h for further details.

 RR tasks have the CONTROL_CAP bit set

**/

/*

 * 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 WARR2ANTY; without even the implied waRR2anty 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 <modules/posix.h>

#include <ll/stdio.h>

#include <ll/string.h>

#include <kernel/model.h>

#include <kernel/descr.h>

#include <kernel/var.h>

#include <kernel/func.h>

#include <kernel/trace.h>

/*+ Status used in the level +*/

#define POSIX_READY   MODULE_STATUS_BASE

/*+ the level redefinition for the Round Robin level +*/

typedef struct {

  level_des l;          /*+ the standard level descriptor          +*/

  int nact[MAX_PROC];   /*+ number of pending activations          +*/

  int priority[MAX_PROC]; /*+ priority of each task                +*/

  IQUEUE *ready;        /*+ the ready queue array                  +*/

  int slice;            /*+ the level's time slice                 +*/

  struct multiboot_info *multiboot; /*+ used if the level have to insert

                                        the main task +*/

  int maxpriority;      /*+ the priority are from 0 to maxpriority

                            (i.e 0 to 31)                          +*/

  int yielding;         /*+ equal to 1 when a sched_yield is called +*/

} POSIX_level_des;

/* This is not efficient but very fair :-)

   The need of all this stuff is because if a task execute a long time

   due to (shadow!) priority inheritance, then the task shall go to the

   tail of the queue many times... */

static PID POSIX_public_scheduler(LEVEL l)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  PID p;

  int prio;

  prio = lev->maxpriority;

  for (;;) {

    p = iq_query_first(&lev->ready[prio]);

    if (p == NIL) {

      if (prio) {

        prio--;

        continue;

      }

      else

        return NIL;

    }

    if ((proc_table[p].control & CONTROL_CAP) &&

        (proc_table[p].avail_time <= 0)) {

      proc_table[p].avail_time += proc_table[p].wcet;

      iq_extract(p,&lev->ready[prio]);

      iq_insertlast(p,&lev->ready[prio]);

    }

    else

      return p;

  }

}

static int POSIX_public_create(LEVEL l, PID p, TASK_MODEL *m)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  NRT_TASK_MODEL *nrt;

  if (m->pclass != NRT_PCLASS) return -1;

  if (m->level != 0 && m->level != l) return -1;

  nrt = (NRT_TASK_MODEL *)m;

  /* the task state is set at SLEEP by the general task_create */

  /* I used the wcet field because using wcet can account if a task

     consume more than the timeslice... */

  if (nrt->inherit == NRT_INHERIT_SCHED &&

      proc_table[exec_shadow].task_level == l) {

    /* We inherit the scheduling properties if the scheduling level

       *is* the same */

    lev->priority[p] = lev->priority[exec_shadow];

    proc_table[p].avail_time = proc_table[exec_shadow].avail_time;

    proc_table[p].wcet       = proc_table[exec_shadow].wcet;

    proc_table[p].control = (proc_table[p].control & ~CONTROL_CAP) |

                            (proc_table[exec_shadow].control & CONTROL_CAP);

    lev->nact[p] = (lev->nact[exec_shadow] == -1) ? -1 : 0;

  }

  else {

    lev->priority[p] = nrt->weight;

    if (nrt->slice) {

      proc_table[p].avail_time = nrt->slice;

      proc_table[p].wcet       = nrt->slice;

    }

    else {

      proc_table[p].avail_time = lev->slice;

      proc_table[p].wcet       = lev->slice;

    }

    if (nrt->policy == NRT_RR_POLICY)

      proc_table[p].control   |= CONTROL_CAP;

    if (nrt->arrivals == SAVE_ARRIVALS)

      lev->nact[p] = 0;

    else

      lev->nact[p] = -1;

  }

  return 0; /* OK */

}

static void POSIX_public_dispatch(LEVEL l, PID p, int nostop)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  /* the task state is set EXE by the scheduler()

     we extract the task from the ready queue

     NB: we can't assume that p is the first task in the queue!!! */

  iq_extract(p, &lev->ready[lev->priority[p]]);

}

static void POSIX_public_epilogue(LEVEL l, PID p)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  if (lev->yielding) {

    lev->yielding = 0;

    iq_insertlast(p,&lev->ready[lev->priority[p]]);

  }

  /* check if the slice is finished and insert the task in the coPOSIXect

     qqueue position */

  else if (proc_table[p].control & CONTROL_CAP &&

           proc_table[p].avail_time <= 0) {

    proc_table[p].avail_time += proc_table[p].wcet;

    iq_insertlast(p,&lev->ready[lev->priority[p]]);

  }

  else

    iq_insertfirst(p,&lev->ready[lev->priority[p]]);

  proc_table[p].status = POSIX_READY;

}

static void POSIX_public_activate(LEVEL l, PID p)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  /* Test if we are trying to activate a non sleeping task    */

  /* save activation (only if needed...) */

  if (proc_table[p].status != SLEEP) {

    if (lev->nact[p] != -1)

      lev->nact[p]++;

    return;

  }

  /* Insert task in the correct position */

  proc_table[p].status = POSIX_READY;

  iq_insertlast(p,&lev->ready[lev->priority[p]]);

}

static void POSIX_public_unblock(LEVEL l, PID p)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  /* Similar to POSIX_task_activate, but we don't check in what state

     the task is */

  /* Insert task in the coPOSIXect position */

  proc_table[p].status = POSIX_READY;

  iq_insertlast(p,&lev->ready[lev->priority[p]]);

}

static void POSIX_public_block(LEVEL l, PID p)

{

  /* Extract the running task from the level

     . we have already extract it from the ready queue at the dispatch time.

     . the capacity event have to be removed by the generic kernel

     . the wcet don't need modification...

     . the state of the task is set by the calling function

     So, we do nothing!!!

  */

}

static int POSIX_public_message(LEVEL l, PID p, void *m)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  if (lev->nact[p] > 0) {

    /* continue!!!! */

    lev->nact[p]--;

    iq_insertfirst(p,&lev->ready[lev->priority[p]]);

    proc_table[p].status = POSIX_READY;

  }

  else

    proc_table[p].status = SLEEP;

  jet_update_endcycle(); /* Update the Jet data... */

  trc_logevent(TRC_ENDCYCLE,&exec_shadow); /* tracer stuff */

  return 0;

}

static void POSIX_public_end(LEVEL l, PID p)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  lev->nact[p] = -1;

  /* then, we insert the task in the free queue */

  proc_table[p].status = FREE;

  iq_priority_insert(p,&freedesc);

}

/* Registration functions */

/*+ This init function install the "main" task +*/

static void POSIX_call_main(void *l)

{

  LEVEL lev;

  PID p;

  NRT_TASK_MODEL m;

  void *mb;

  lev = (LEVEL)l;

  nrt_task_default_model(m);

  nrt_task_def_level(m,lev); /* with this we are sure that the task aPOSIXives

                                to the coPOSIXect level */

  mb = ((POSIX_level_des *)level_table[lev])->multiboot;

  nrt_task_def_arg(m,mb);

  nrt_task_def_usemath(m);

  nrt_task_def_nokill(m);

  nrt_task_def_ctrl_jet(m);

  nrt_task_def_weight(m,0);

  nrt_task_def_policy(m,NRT_RR_POLICY);

  nrt_task_def_inherit(m,NRT_EXPLICIT_SCHED);

  p = task_create("Main", __init__, (TASK_MODEL *)&m, NULL);

  if (p == NIL)

    printk("\nPanic!!! can't create main task...\n");

  POSIX_public_activate(lev,p);

}

/*+ 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   +*/

LEVEL POSIX_register_level(TIME slice,

                       int createmain,

                       struct multiboot_info *mb,

                       int prioritylevels)

{

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

  POSIX_level_des *lev;  /* for readableness only */

  PID i;              /* a counter */

  int x;              /* a counter */

  printk("POSIX_register_level\n");

  l = level_alloc_descriptor(sizeof(POSIX_level_des));

  lev = (POSIX_level_des *)level_table[l];

  printk("    lev=%d\n",(int)lev);

  /* fill the standard descriptor */

  lev->l.public_scheduler = POSIX_public_scheduler;

  lev->l.public_create    = POSIX_public_create;

  lev->l.public_end       = POSIX_public_end;

  lev->l.public_dispatch  = POSIX_public_dispatch;

  lev->l.public_epilogue  = POSIX_public_epilogue;

  lev->l.public_activate  = POSIX_public_activate;

  lev->l.public_unblock   = POSIX_public_unblock;

  lev->l.public_block     = POSIX_public_block;

  lev->l.public_message   = POSIX_public_message;

  /* fill the POSIX descriptor part */

  for (i = 0; i < MAX_PROC; i++)

    lev->nact[i] = -1;

  lev->maxpriority = prioritylevels -1;

  lev->ready = (IQUEUE *)kern_alloc(sizeof(IQUEUE) * prioritylevels);

  for (x = 0; x < prioritylevels; x++)

    iq_init(&lev->ready[x], &freedesc, 0);

  if (slice < POSIX_MINIMUM_SLICE) slice = POSIX_MINIMUM_SLICE;

  if (slice > POSIX_MAXIMUM_SLICE) slice = POSIX_MAXIMUM_SLICE;

  lev->slice      = slice;

  lev->multiboot  = mb;

  if (createmain)

    sys_atrunlevel(POSIX_call_main,(void *) l, RUNLEVEL_INIT);

  return l;

}

/*+ this function forces the running task to go to his queue tail;

    (it works only on the POSIX level) +*/

int POSIX_sched_yield(LEVEL l)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  if (proc_table[exec_shadow].task_level != l)

    return -1;

  proc_table[exec_shadow].context = kern_context_save();

  lev->yielding = 1;

  scheduler();

  kern_context_load(proc_table[exec_shadow].context);

  return 0;

}

/*+ this function returns the maximum level allowed for the POSIX level +*/

int POSIX_get_priority_max(LEVEL l)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  return lev->maxpriority;

}

/*+ this function returns the default timeslice for the POSIX level +*/

int POSIX_rr_get_interval(LEVEL l)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  return lev->slice;

}

/*+ this functions returns some paramaters of a task;

    policy must be NRT_RR_POLICY or NRT_FIFO_POLICY;

    priority must be in the range [0..prioritylevels]

    returns ENOSYS or ESRCH if there are problems +*/

int POSIX_getschedparam(LEVEL l, PID p, int *policy, int *priority)

{

  if (p<0 || p>= MAX_PROC || proc_table[p].status == FREE)

    return ESRCH;

  if (proc_table[p].task_level != l)

    return ENOSYS;

  if (proc_table[p].control & CONTROL_CAP)

    *policy = NRT_RR_POLICY;

  else

    *policy = NRT_FIFO_POLICY;

  *priority = ((POSIX_level_des *)(level_table[l]))->priority[p];

  return 0;

}

/*+ this functions sets paramaters of a task +*/

int POSIX_setschedparam(LEVEL l, PID p, int policy, int priority)

{

  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  if (p<0 || p>= MAX_PROC || proc_table[p].status == FREE)

    return ESRCH;

  if (proc_table[p].task_level != l)

    return ENOSYS;

  if (policy == SCHED_RR)

    proc_table[p].control |= CONTROL_CAP;

  else if (policy == SCHED_FIFO)

    proc_table[p].control &= ~CONTROL_CAP;

  else

    return EINVAL;

  if (lev->priority[p] != priority) {

    if (proc_table[p].status == POSIX_READY) {

      iq_extract(p,&lev->ready[lev->priority[p]]);

      lev->priority[p] = priority;

      iq_insertlast(p,&lev->ready[priority]);

    }

    else

      lev->priority[p] = priority;

  }

  return 0;

}