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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 1.1.1.1 2002-03-29 14:12:52 pj Exp $

 File:        $File$
 Revision:    $Revision: 1.1.1.1 $
 Last update: $Date: 2002-03-29 14:12:52 $
 ------------

 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>

/*+ Status used in the level +*/
#define POSIX_READY   MODULE_STATUS_BASE
#define POSIX_DELAY   MODULE_STATUS_BASE+1

/*+ 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          +*/

  QQUEUE *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;

static char *POSIX_status_to_a(WORD status)
{
  if (status < MODULE_STATUS_BASE)
    return status_to_a(status);

  switch (status) {
    case POSIX_READY: return "POSIX_Ready";
    case POSIX_DELAY: return "POSIX_Delay";
    default         : return "POSIX_Unknown";
  }
}

/*+ this function is called when a task finish his delay +*/
static void POSIX_timer_delay(void *par)
{
  PID p = (PID) par;
  POSIX_level_des *lev;

  lev = (POSIX_level_des *)level_table[proc_table[p].task_level];

  proc_table[p].status = POSIX_READY;
  qq_insertlast(p,&lev->ready[proc_table[p].priority]);

  proc_table[p].delay_timer = NIL;  /* Paranoia */

//  kern_printf(" DELAY TIMER %d ", p);

  event_need_reschedule();
}


static int POSIX_level_accept_task_model(LEVEL l, TASK_MODEL *m)
{
  if (m->pclass == NRT_PCLASS || m->pclass == (NRT_PCLASS | l))
    return 0;
  else
    return -1;
}

static int POSIX_level_accept_guest_model(LEVEL l, TASK_MODEL *m)
{
    return -1;
}

static void POSIX_level_status(LEVEL l)
{
  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);
  PID p;

  kern_printf("Slice: %d \n", lev->slice);

  for (p=0; p<MAX_PROC; p++)
    if (proc_table[p].task_level == l && proc_table[p].status != POSIX_READY
        && proc_table[p].status != FREE )
      kern_printf("Pid: %d\t Name: %20s Prio: %3ld Status: %s\n",
                  p,proc_table[p].name,
                  proc_table[p].priority,
                  POSIX_status_to_a(proc_table[p].status));

}


/* 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_level_scheduler(LEVEL l)
{
  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  PID p;

  int prio;

  prio = lev->maxpriority;

  for (;;) {
    p = qq_queryfirst(&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;
      qq_extract(p,&lev->ready[prio]);
      qq_insertlast(p,&lev->ready[prio]);
    }
    else
      return p;
  }
}

static int POSIX_level_guarantee(LEVEL l, bandwidth_t *freebandwidth)
{
  /* the POSIX level always guarantee... the function is defined because
     there can be an aperiodic server at a level with less priority than
     the POSIX that need guarantee (e.g., a TBS server) */
  return 1;
}


static int POSIX_task_create(LEVEL l, PID p, TASK_MODEL *m)
{
  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);
  NRT_TASK_MODEL *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 */
    proc_table[p].priority = proc_table[exec_shadow].priority;
 
    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 {
    proc_table[p].priority = 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_task_detach(LEVEL l, PID p)
{
  /* the POSIX level doesn't introduce any new field in the TASK_MODEL
     so, all detach stuffs are done by the task_create
     The task state is set at FREE by the general task_create */
}

static int POSIX_task_eligible(LEVEL l, PID p)
{
  return 0; /* if the task p is chosen, it is always eligible */
}

#ifdef __TEST1__
extern int testactive;
extern struct timespec s_stime[];
extern TIME s_curr[];
extern TIME s_PID[];
extern int useds;
#endif

static void POSIX_task_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!!! */
  qq_extract(p, &lev->ready[proc_table[p].priority]);


  #ifdef __TEST1__
  if (testactive)
  {
    TIMESPEC_ASSIGN(&s_stime[useds],&schedule_time);
    s_curr[useds] = proc_table[p].avail_time;
    s_PID[useds]  = p;
    useds++;
  }
  #endif
}

static void POSIX_task_epilogue(LEVEL l, PID p)
{
  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  if (lev->yielding) {
    lev->yielding = 0;
    qq_insertlast(p,&lev->ready[proc_table[p].priority]);
  }
  /* 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;
    qq_insertlast(p,&lev->ready[proc_table[p].priority]);
  }
  else
    qq_insertfirst(p,&lev->ready[proc_table[p].priority]);

  proc_table[p].status = POSIX_READY;
}

static void POSIX_task_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;
  }

  ll_gettime(TIME_EXACT, &proc_table[p].request_time);

  /* Insert task in the correct position */
  proc_table[p].status = POSIX_READY;
  qq_insertlast(p,&lev->ready[proc_table[p].priority]);
}

static void POSIX_task_insert(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 and we don't set the request_time */

  /* Insert task in the coPOSIXect position */
  proc_table[p].status = POSIX_READY;
  qq_insertlast(p,&lev->ready[proc_table[p].priority]);
}

static void POSIX_task_extract(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 void POSIX_task_endcycle(LEVEL l, PID p)
{
  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);

  if (lev->nact[p] > 0) {
    /* continue!!!! */
    ll_gettime(TIME_EXACT, &proc_table[p].request_time);
    lev->nact[p]--;
    qq_insertfirst(p,&lev->ready[proc_table[p].priority]);
    proc_table[p].status = POSIX_READY;
  }
  else
    proc_table[p].status = SLEEP;
}

static void POSIX_task_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;
  q_insert(p,&freedesc);
}

static void POSIX_task_sleep(LEVEL l, PID p)
{
  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);
  lev->nact[p] = 0;
  proc_table[p].status = SLEEP;
}

static void POSIX_task_delay(LEVEL l, PID p, TIME usdelay)
{
//  POSIX_level_des *lev = (POSIX_level_des *)(level_table[l]);
  struct timespec wakeuptime;

  /* equal to POSIX_task_endcycle */
  proc_table[p].status = POSIX_DELAY;

  /* we need to delete this event if we kill the task while it is sleeping */
  ll_gettime(TIME_EXACT,&wakeuptime);
  ADDUSEC2TIMESPEC(usdelay,&wakeuptime);
  proc_table[p].delay_timer = kern_event_post(&wakeuptime,
                                              POSIX_timer_delay,
                                              (void *)p);
}


static int POSIX_guest_create(LEVEL l, PID p, TASK_MODEL *m)
{ kern_raise(XUNVALID_GUEST,exec_shadow); return 0; }

static void POSIX_guest_detach(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_dispatch(LEVEL l, PID p, int nostop)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_epilogue(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_activate(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_insert(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_extract(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_endcycle(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_end(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_sleep(LEVEL l, PID p)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }

static void POSIX_guest_delay(LEVEL l, PID p,DWORD tickdelay)
{ kern_raise(XUNVALID_GUEST,exec_shadow); }




/* 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_task_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   +*/
void 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");

  /* request an entry in the level_table */
  l = level_alloc_descriptor();

  printk("    alloco descrittore %d %d\n",l,(int)sizeof(POSIX_level_des));

  /* alloc the space needed for the POSIX_level_des */
  lev = (POSIX_level_des *)kern_alloc(sizeof(POSIX_level_des));

  printk("    lev=%d\n",(int)lev);

  /* update the level_table with the new entry */
  level_table[l] = (level_des *)lev;

  /* fill the standard descriptor */
  strncpy(lev->l.level_name,  POSIX_LEVELNAME, MAX_LEVELNAME);
  lev->l.level_code               = POSIX_LEVEL_CODE;
  lev->l.level_version            = POSIX_LEVEL_VERSION;

  lev->l.level_accept_task_model  = POSIX_level_accept_task_model;
  lev->l.level_accept_guest_model = POSIX_level_accept_guest_model;
  lev->l.level_status             = POSIX_level_status;
  lev->l.level_scheduler          = POSIX_level_scheduler;
  lev->l.level_guarantee          = POSIX_level_guarantee;

  lev->l.task_create              = POSIX_task_create;
  lev->l.task_detach              = POSIX_task_detach;
  lev->l.task_eligible            = POSIX_task_eligible;
  lev->l.task_dispatch            = POSIX_task_dispatch;
  lev->l.task_epilogue            = POSIX_task_epilogue;
  lev->l.task_activate            = POSIX_task_activate;
  lev->l.task_insert              = POSIX_task_insert;
  lev->l.task_extract             = POSIX_task_extract;
  lev->l.task_endcycle            = POSIX_task_endcycle;
  lev->l.task_end                 = POSIX_task_end;
  lev->l.task_sleep               = POSIX_task_sleep;
  lev->l.task_delay               = POSIX_task_delay;

  lev->l.guest_create             = POSIX_guest_create;
  lev->l.guest_detach             = POSIX_guest_detach;
  lev->l.guest_dispatch           = POSIX_guest_dispatch;
  lev->l.guest_epilogue           = POSIX_guest_epilogue;
  lev->l.guest_activate           = POSIX_guest_activate;
  lev->l.guest_insert             = POSIX_guest_insert;
  lev->l.guest_extract            = POSIX_guest_extract;
  lev->l.guest_endcycle           = POSIX_guest_endcycle;
  lev->l.guest_end                = POSIX_guest_end;
  lev->l.guest_sleep              = POSIX_guest_sleep;
  lev->l.guest_delay              = POSIX_guest_delay;

  /* fill the POSIX descriptor part */
  for (i = 0; i < MAX_PROC; i++)
    lev->nact[i] = -1;

  lev->maxpriority = prioritylevels -1;

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

  for (x = 0; x < prioritylevels; x++)
    qq_init(&lev->ready[x]);

  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);
}

/*+ 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 (l < 0 || l >= sched_levels)
    return -1;

  if (level_table[l]->level_code    != POSIX_LEVEL_CODE    ||
      level_table[l]->level_version != POSIX_LEVEL_VERSION )
    return -1;

  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 (l < 0 || l >= sched_levels)
    return ENOSYS;

  if (level_table[l]->level_code    != POSIX_LEVEL_CODE    ||
      level_table[l]->level_version != POSIX_LEVEL_VERSION )
    return ENOSYS;

  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 = proc_table[p].priority;

  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 (l < 0 || l >= sched_levels)
    return ENOSYS;

  if (level_table[l]->level_code    != POSIX_LEVEL_CODE    ||
      level_table[l]->level_version != POSIX_LEVEL_VERSION )
    return ENOSYS;

  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 (proc_table[p].priority != priority) {
    if (proc_table[p].status == POSIX_READY) {
      qq_extract(p,&lev->ready[proc_table[p].priority]);
      proc_table[p].priority = priority;
      qq_insertlast(p,&lev->ready[priority]);
    }
    else
      proc_table[p].priority = priority;
  }

  return 0;
}