238 lines
6.2 KiB
C
238 lines
6.2 KiB
C
/* This file is part of the program psim.
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Copyright (C) 1994-1995, Andrew Cagney <cagney@highland.com.au>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifndef _EVENTS_C_
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#define _EVENTS_C_
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#ifndef STATIC_INLINE_EVENTS
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#define STATIC_INLINE_EVENTS STATIC_INLINE
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#endif
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#include "basics.h"
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#include "events.h"
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/* The event queue maintains a single absolute time using two
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variables.
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TIME_OF_EVENT: this holds the time at which the next event is ment
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to occure. If no next event it will hold the time of the last
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event. The first event occures at time 0 - system start.
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TIME_FROM_EVENT: The current distance from TIME_OF_EVENT. If an
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event is pending, this will be positive. If no future event is
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pending this will be negative. This variable is decremented once
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for each iteration of a clock cycle.
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Clearly there is a bug in that this code assumes that the absolute
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time counter will never become greater than 2^62. */
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typedef struct _event_entry event_entry;
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struct _event_entry {
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void *data;
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event_handler *handler;
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signed64 time_of_event;
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event_entry *next;
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};
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struct _event_queue {
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event_entry *queue;
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event_entry *volatile held;
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event_entry *volatile *volatile held_end;
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signed64 time_of_event;
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signed64 time_from_event;
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};
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INLINE_EVENTS event_queue *
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event_queue_create(void)
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{
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event_queue *new_event_queue = ZALLOC(event_queue);
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new_event_queue->queue = NULL;
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new_event_queue->held = NULL;
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new_event_queue->held_end = &new_event_queue->held;
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/* both times are already zero */
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return new_event_queue;
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}
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STATIC_INLINE_EVENTS void
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insert_event_entry(event_queue *events,
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event_entry *new_event,
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signed64 delta)
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{
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event_entry *curr;
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event_entry **last;
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signed64 time_of_event;
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if (delta <= 0)
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error("can not schedule event for current time\n");
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/* compute when the event should occure */
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time_of_event = (events->time_of_event
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- events->time_from_event
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+ delta);
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/* find the queue insertion point - things are time ordered */
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last = &events->queue;
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curr = events->queue;
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while (curr != NULL && time_of_event >= curr->time_of_event) {
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last = &curr->next;
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curr = curr->next;
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}
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/* insert it */
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new_event->next = curr;
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*last = new_event;
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new_event->time_of_event = time_of_event;
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/* adjust the time until the first event */
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events->time_from_event = (events->queue->time_of_event
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- (events->time_of_event
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- events->time_from_event));
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events->time_of_event = events->queue->time_of_event;
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}
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INLINE_EVENTS event_entry_tag
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event_queue_schedule(event_queue *events,
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signed64 delta_time,
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event_handler *handler,
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void *data)
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{
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event_entry *new_event = ZALLOC(event_entry);
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new_event->data = data;
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new_event->handler = handler;
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insert_event_entry(events, new_event, delta_time);
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return new_event;
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}
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INLINE_EVENTS event_entry_tag
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event_queue_schedule_after_signal(event_queue *events,
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signed64 delta_time,
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event_handler *handler,
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void *data)
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{
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event_entry *new_event = ZALLOC(event_entry);
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new_event->data = data;
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new_event->handler = handler;
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new_event->time_of_event = delta_time; /* work it out later */
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new_event->next = NULL;
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/*-LOCK-*/
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if (events->held == NULL) {
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events->held = new_event;
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}
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else {
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*events->held_end = new_event;
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}
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events->held_end = &new_event->next;
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/*-UNLOCK-*/
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return new_event;
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}
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INLINE_EVENTS void
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event_queue_deschedule(event_queue *events,
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event_entry_tag event_to_remove)
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{
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if (event_to_remove != NULL) {
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event_entry *current;
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event_entry **ptr_to_current;
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for (ptr_to_current = &events->queue, current = *ptr_to_current;
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current != NULL && current != event_to_remove;
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ptr_to_current = ¤t->next, current = *ptr_to_current);
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if (current == event_to_remove) {
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*ptr_to_current = current->next;
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zfree(current);
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/* Just forget to recompute the delay to the next event */
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}
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}
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}
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INLINE_EVENTS int
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event_queue_tick(event_queue *events)
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{
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/* remove things from the asynchronous event queue onto the real one */
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if (events->held != NULL) {
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event_entry *held_events;
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event_entry *curr_event;
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/*-LOCK-*/
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held_events = events->held;
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events->held = NULL;
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events->held_end = &events->held;
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/*-UNLOCK-*/
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do {
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curr_event = held_events;
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held_events = curr_event->next;
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insert_event_entry(events, curr_event, curr_event->time_of_event);
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} while (held_events != NULL);
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}
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/* advance time, checking to see if we've reached time zero which
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would indicate the time for the next event has arrived */
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events->time_from_event -= 1;
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return events->time_from_event == 0;
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}
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INLINE_EVENTS void
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event_queue_process(event_queue *events)
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{
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if (events->time_from_event == 0) {
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/* consume all events for this or earlier times */
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do {
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event_entry *to_do = events->queue;
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events->queue = to_do->next;
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to_do->handler(events,
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to_do->data);
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zfree(to_do);
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} while (events->queue != NULL
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&& events->queue->time_of_event <= events->time_of_event);
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/* re-caculate time for new events */
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if (events->queue != NULL) {
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events->time_from_event = (events->queue->time_of_event
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- events->time_of_event);
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events->time_of_event = events->queue->time_of_event;
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}
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else {
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/* nothing to do, time_from_event will go negative */
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}
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}
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}
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INLINE_EVENTS signed64
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event_queue_time(event_queue *queue)
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{
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return queue->time_of_event - queue->time_from_event;
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}
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#endif /* _EVENTS_C_ */
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