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/* sched.c -- Abstract entities, handling job scheduling

   Copyright (C) 2001 Marko Mlinar, markom@opencores.org

   Copyright (C) 2008 Embecosm Limited

   Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>

   This file is part of Or1ksim, the OpenRISC 1000 Architectural Simulator.

   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 3 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 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, see <http://www.gnu.org/licenses/>.  */

/* This program is commented throughout in a fashion suitable for processing

   with Doxygen. */

/* Autoconf and/or portability configuration */

#include "config.h"

#include "port.h"

/* System includes */

#include <stdlib.h>

#include <stdio.h>

#include <limits.h>

/* Package includes */

#include "sched.h"

#include "debug.h"

#include "sim-config.h"

DECLARE_DEBUG_CHANNEL(sched_jobs);

#define SCHED_HEAP_SIZE 128

#define SCHED_TIME_MAX  INT32_MAX

/* FIXME: Scheduler should continue from previous cycles not current ones */

struct scheduler_struct scheduler;

/* Dummy function, representing a guard, which protects heap from

   emptying */

void sched_guard (void *dat)

{

  if(scheduler.job_queue)

    SCHED_ADD(sched_guard, dat, SCHED_TIME_MAX);

  else {

    scheduler.job_queue = scheduler.free_job_queue;

    scheduler.free_job_queue = scheduler.free_job_queue->next;

    scheduler.job_queue->next = NULL;

    scheduler.job_queue->func = sched_guard;

    scheduler.job_queue->time = SCHED_TIME_MAX;

  }

}

void sched_reset(void)

{

  struct sched_entry *cur, *next;

  for(cur = scheduler.job_queue; cur; cur = next) {

    next = cur->next;

    cur->next = scheduler.free_job_queue;

    scheduler.free_job_queue = cur;

  }

  scheduler.job_queue = NULL;

  sched_guard(NULL);

}

void sched_init(void)

{

  int i;

  struct sched_entry *new;

  scheduler.free_job_queue = NULL;

  for(i = 0; i < SCHED_HEAP_SIZE; i++) {

    if(!(new = malloc(sizeof(struct sched_entry)))) {

      fprintf(stderr, "Out-of-memory while allocateing scheduler queue\n");

      exit(1);

    }

    new->next = scheduler.free_job_queue;

    scheduler.free_job_queue = new;

  }

  scheduler.job_queue = NULL;

  sched_guard(NULL);

}

/* Executes jobs in time queue */

void do_scheduler(void)

{

  struct sched_entry *tmp;

  /* Execute all jobs till now */

  do {

    tmp = scheduler.job_queue;

    scheduler.job_queue = tmp->next;

    tmp->next = scheduler.free_job_queue;

    scheduler.free_job_queue = tmp;

    scheduler.job_queue->time += tmp->time;

    tmp->func (tmp->param);

  } while(scheduler.job_queue->time <= 0);

}

/* Adds new job to the queue */

void sched_add(void (*job_func)(void *), void *job_param, int32_t job_time,

               const char *func)

{

  struct sched_entry *cur, *prev, *new_job;

  int32_t alltime;

  cur = scheduler.job_queue;

  prev = NULL;

  alltime = cur->time;

  while(cur && (alltime < job_time)) {

    prev = cur;

    cur = cur->next;

    if(cur)

      alltime += cur->time;

  }

  new_job = scheduler.free_job_queue;

  scheduler.free_job_queue = new_job->next;

  new_job->next = cur;

  new_job->func = job_func;

  new_job->param = job_param;

  if(prev) {

    new_job->time = job_time - (alltime - (cur ? cur->time : 0));

    prev->next = new_job;

  } else {

    scheduler.job_queue = new_job;

    new_job->time = job_time >= 0 ? job_time : cur->time;

  }

  if(cur)

    cur->time -= new_job->time;

}

/* Returns a job with specified function and param, NULL if not found */

void sched_find_remove(void (*job_func)(void *), void *dat)

{

  struct sched_entry *cur;

  struct sched_entry *prev = NULL;

  for (cur = scheduler.job_queue; cur; prev = cur, cur = cur->next) {

    if ((cur->func == job_func) && (cur->param == dat)) {

      if(cur->next)

        cur->next->time += cur->time;

      if(prev)

        prev->next = cur->next;

      else

        scheduler.job_queue = cur->next;

      cur->next = scheduler.free_job_queue;

      scheduler.free_job_queue = cur;

      break;

    }

  }

}

/* Schedules the next job so that it will run after the next instruction */

void sched_next_insn(void (*func)(void *), void *dat)

{

  int32_t cycles = 1;

  struct sched_entry *cur = scheduler.job_queue;

  /* The cycles count of the jobs may go into negatives.  If this happens, func

   * will get called before the next instruction has executed. */

  while(cur && (cur->time < 0)) {

    cycles -= cur->time;

    cur = cur->next;

  }

  SCHED_ADD(func, dat, cycles);

}