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/*  This file is part of the program psim.

    Copyright (C) 1994-1998, Andrew Cagney <cagney@highland.com.au>

    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

    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.

    */

#ifndef _EVENTS_C_

#define _EVENTS_C_

#include "basics.h"

#include "events.h"

#include <signal.h>

#if !defined (SIM_EVENTS_POLL_RATE)

#define SIM_EVENTS_POLL_RATE 0x1000

#endif

/* The event queue maintains a single absolute time using two

   variables.

   TIME_OF_EVENT: this holds the time at which the next event is ment

   to occure.  If no next event it will hold the time of the last

   event.

   TIME_FROM_EVENT: The current distance from TIME_OF_EVENT.  If an

   event is pending, this will be positive.  If no future event is

   pending this will be negative.  This variable is decremented once

   for each iteration of a clock cycle.

   Initially, the clock is started at time one (1) with TIME_OF_EVENT

   == 0 and TIME_FROM_EVENT == -1.

   Clearly there is a bug in that this code assumes that the absolute

   time counter will never become greater than 2^62. */

typedef struct _event_entry event_entry;

struct _event_entry {

  void *data;

  event_handler *handler;

  signed64 time_of_event;

  event_entry *next;

};

struct _event_queue {

  int processing;

  event_entry *queue;

  event_entry *volatile held;

  event_entry *volatile *volatile held_end;

  signed64 time_of_event;

  signed64 time_from_event;

};

STATIC_INLINE_EVENTS\

(void)

sim_events_poll (void *data)

{

  event_queue *queue = data;

  /* just re-schedule in 1000 million ticks time */

  event_queue_schedule (queue, SIM_EVENTS_POLL_RATE, sim_events_poll, queue);

  sim_io_poll_quit ();

}

INLINE_EVENTS\

(event_queue *)

event_queue_create(void)

{

  event_queue *new_event_queue = ZALLOC(event_queue);

  new_event_queue->processing = 0;

  new_event_queue->queue = NULL;

  new_event_queue->held = NULL;

  new_event_queue->held_end = &new_event_queue->held;

  /* both times are already zero */

  return new_event_queue;

}

INLINE_EVENTS\

(void)

event_queue_init(event_queue *queue)

{

  event_entry *event;

  /* drain the interrupt queue */

  {

#if defined(HAVE_SIGPROCMASK) && defined(SIG_SETMASK)

    sigset_t old_mask;

    sigset_t new_mask;

    sigfillset(&new_mask);

    /*-LOCK-*/ sigprocmask(SIG_SETMASK, &new_mask, &old_mask);

#endif

    event = queue->held;

    while (event != NULL) {

      event_entry *dead = event;

      event = event->next;

      zfree(dead);

    }

    queue->held = NULL;

    queue->held_end = &queue->held;

#if defined(HAVE_SIGPROCMASK) && defined(SIG_SETMASK)

    /*-UNLOCK-*/ sigprocmask(SIG_SETMASK, &old_mask, NULL);

#endif

  }

  /* drain the normal queue */

  event = queue->queue;

  while (event != NULL) {

    event_entry *dead = event;

    event = event->next;

    zfree(dead);

  }

  queue->queue = NULL;

  /* wind time back to one */

  queue->processing = 0;

  queue->time_of_event = 0;

  queue->time_from_event = -1;

  /* schedule our initial counter event */

  event_queue_schedule (queue, 0, sim_events_poll, queue);

}

INLINE_EVENTS\

(signed64)

event_queue_time(event_queue *queue)

{

  return queue->time_of_event - queue->time_from_event;

}

STATIC_INLINE_EVENTS\

(void)

update_time_from_event(event_queue *events)

{

  signed64 current_time = event_queue_time(events);

  if (events->queue != NULL) {

    events->time_from_event = (events->queue->time_of_event - current_time);

    events->time_of_event = events->queue->time_of_event;

  }

  else {

    events->time_of_event = current_time - 1;

    events->time_from_event = -1;

  }

  if (WITH_TRACE && ppc_trace[trace_events])

    {

      event_entry *event;

      int i;

      for (event = events->queue, i = 0;

           event != NULL;

           event = event->next, i++)

        {

          TRACE(trace_events, ("event time-from-event - time %ld, delta %ld - event %d, tag 0x%lx, time %ld, handler 0x%lx, data 0x%lx\n",

                               (long)current_time,

                               (long)events->time_from_event,

                               i,

                               (long)event,

                               (long)event->time_of_event,

                               (long)event->handler,

                               (long)event->data));

        }

    }

  ASSERT(current_time == event_queue_time(events));

}

STATIC_INLINE_EVENTS\

(void)

insert_event_entry(event_queue *events,

                   event_entry *new_event,

                   signed64 delta)

{

  event_entry *curr;

  event_entry **prev;

  signed64 time_of_event;

  if (delta < 0)

    error("what is past is past!\n");

  /* compute when the event should occure */

  time_of_event = event_queue_time(events) + delta;

  /* find the queue insertion point - things are time ordered */

  prev = &events->queue;

  curr = events->queue;

  while (curr != NULL && time_of_event >= curr->time_of_event) {

    ASSERT(curr->next == NULL

           || curr->time_of_event <= curr->next->time_of_event);

    prev = &curr->next;

    curr = curr->next;

  }

  ASSERT(curr == NULL || time_of_event < curr->time_of_event);

  /* insert it */

  new_event->next = curr;

  *prev = new_event;

  new_event->time_of_event = time_of_event;

  /* adjust the time until the first event */

  update_time_from_event(events);

}

INLINE_EVENTS\

(event_entry_tag)

event_queue_schedule(event_queue *events,

                     signed64 delta_time,

                     event_handler *handler,

                     void *data)

{

  event_entry *new_event = ZALLOC(event_entry);

  new_event->data = data;

  new_event->handler = handler;

  insert_event_entry(events, new_event, delta_time);

  TRACE(trace_events, ("event scheduled at %ld - tag 0x%lx - time %ld, handler 0x%lx, data 0x%lx\n",

                       (long)event_queue_time(events),

                       (long)new_event,

                       (long)new_event->time_of_event,

                       (long)new_event->handler,

                       (long)new_event->data));

  return (event_entry_tag)new_event;

}

INLINE_EVENTS\

(event_entry_tag)

event_queue_schedule_after_signal(event_queue *events,

                                  signed64 delta_time,

                                  event_handler *handler,

                                  void *data)

{

  event_entry *new_event = ZALLOC(event_entry);

  new_event->data = data;

  new_event->handler = handler;

  new_event->time_of_event = delta_time; /* work it out later */

  new_event->next = NULL;

  {

#if defined(HAVE_SIGPROCMASK) && defined(SIG_SETMASK)

    sigset_t old_mask;

    sigset_t new_mask;

    sigfillset(&new_mask);

    /*-LOCK-*/ sigprocmask(SIG_SETMASK, &new_mask, &old_mask);

#endif

    if (events->held == NULL) {

      events->held = new_event;

    }

    else {

      *events->held_end = new_event;

    }

    events->held_end = &new_event->next;

#if defined(HAVE_SIGPROCMASK) && defined(SIG_SETMASK)

    /*-UNLOCK-*/ sigprocmask(SIG_SETMASK, &old_mask, NULL);

#endif

  }

  TRACE(trace_events, ("event scheduled at %ld - tag 0x%lx - time %ld, handler 0x%lx, data 0x%lx\n",

                       (long)event_queue_time(events),

                       (long)new_event,

                       (long)new_event->time_of_event,

                       (long)new_event->handler,

                       (long)new_event->data));

  return (event_entry_tag)new_event;

}

INLINE_EVENTS\

(void)

event_queue_deschedule(event_queue *events,

                       event_entry_tag event_to_remove)

{

  event_entry *to_remove = (event_entry*)event_to_remove;

  ASSERT((events->time_from_event >= 0) == (events->queue != NULL));

  if (event_to_remove != NULL) {

    event_entry *current;

    event_entry **ptr_to_current;

    for (ptr_to_current = &events->queue, current = *ptr_to_current;

         current != NULL && current != to_remove;

         ptr_to_current = &current->next, current = *ptr_to_current);

    if (current == to_remove) {

      *ptr_to_current = current->next;

      TRACE(trace_events, ("event descheduled at %ld - tag 0x%lx - time %ld, handler 0x%lx, data 0x%lx\n",

                           (long)event_queue_time(events),

                           (long)event_to_remove,

                           (long)current->time_of_event,

                           (long)current->handler,

                           (long)current->data));

      zfree(current);

      update_time_from_event(events);

    }

    else {

      TRACE(trace_events, ("event descheduled at %ld - tag 0x%lx - not found\n",

                           (long)event_queue_time(events),

                           (long)event_to_remove));

    }

  }

  ASSERT((events->time_from_event >= 0) == (events->queue != NULL));

}

INLINE_EVENTS\

(int)

event_queue_tick(event_queue *events)

{

  signed64 time_from_event;

  /* we should only be here when the previous tick has been fully processed */

  ASSERT(!events->processing);

  /* move any events that were queued by any signal handlers onto the

     real event queue.  BTW: When inlining, having this code here,

     instead of in event_queue_process() causes GCC to put greater

     weight on keeping the pointer EVENTS in a register.  This, in

     turn results in better code being output. */

  if (events->held != NULL) {

    event_entry *held_events;

    event_entry *curr_event;

    {

#if defined(HAVE_SIGPROCMASK) && defined(SIG_SETMASK)

      sigset_t old_mask;

      sigset_t new_mask;

      sigfillset(&new_mask);

      /*-LOCK-*/ sigprocmask(SIG_SETMASK, &new_mask, &old_mask);

#endif

      held_events = events->held;

      events->held = NULL;

      events->held_end = &events->held;

#if defined(HAVE_SIGPROCMASK) && defined(SIG_SETMASK)

      /*-UNLOCK-*/ sigprocmask(SIG_SETMASK, &old_mask, NULL);

#endif

    }

    do {

      curr_event = held_events;

      held_events = curr_event->next;

      insert_event_entry(events, curr_event, curr_event->time_of_event);

    } while (held_events != NULL);

  }

  /* advance time, checking to see if we've reached time zero which

     would indicate the time for the next event has arrived */

  time_from_event = events->time_from_event;

  events->time_from_event = time_from_event - 1;

  return time_from_event == 0;

}

INLINE_EVENTS\

(void)

event_queue_process(event_queue *events)

{

  signed64 event_time = event_queue_time(events);

  ASSERT((events->time_from_event == -1 && events->queue != NULL)

         || events->processing); /* something to do */

  /* consume all events for this or earlier times.  Be careful to

     allow a new event to appear under our feet */

  events->processing = 1;

  while (events->queue != NULL

         && events->queue->time_of_event <= event_time) {

    event_entry *to_do = events->queue;

    event_handler *handler = to_do->handler;

    void *data = to_do->data;

    events->queue = to_do->next;

    TRACE(trace_events, ("event issued at %ld - tag 0x%lx - time %ld, handler 0x%lx, data 0x%lx\n",

                         (long)event_time,

                         (long)to_do,

                         (long)to_do->time_of_event,

                         (long)handler,

                         (long)data));

    zfree(to_do);

    /* Always re-compute the time to the next event so that HANDLER()

       can safely insert new events into the queue. */

    update_time_from_event(events);

    handler(data);

  }

  events->processing = 0;

  ASSERT(events->time_from_event > 0);

  ASSERT(events->queue != NULL); /* always poll event */

}

#endif /* _EVENTS_C_ */