#ifndef lint
static char sccsid[] = "@(#)monitor.c 9.2 88/01/19 Copyright 1987 Sun Micro";
#endif

/*
 * Copyright (c) 1987 by Sun Microsystems, Inc.
 */

/*-
	Routines for dealing with PostScript monitors

	monitor.c, Wed Sep 24 10:33:35 1986

		James Gosling,
		Sun Microsystems
 */

#ifdef REF
#include <sys/types.h>
#include <ref/config.h>
#endif
#include "PostScript.h"

static
createmonitor(ee)
    register struct execution_environment *ee;
{
    register struct body *p = new_body(monitor);
    set_typed_bodied_object(ee->optop, monitor_type, p);
    p->type = monitor_type;
    p->body.monitor.holder = 0;
    p->body.monitor.first = 0;
    p->body.monitor.last = 0;
    p->body.monitor.reentry_depth = 0;
    ee->optop++;
}

static
monitorlocked(ee)
    register struct execution_environment *ee;
{
    register struct object *optop = ee->optop;
    register fract ret;
    if (optop[-1].type != monitor_type) {
	ee->error_code = typecheck_error_code;
	return;
    }
    ret = fracti(body_of(optop - 1)->body.monitor.holder != 0);
    decref(body_of(optop - 1));
    set_typed_object(optop - 1, boolean_type);
    optop[-1].value.fixed = ret;
    return;
}

disentangle_monitor(ee, b)
    register struct execution_environment *ee;
    register struct body *b;
{
    assert(b->type == monitor_type);
    if (ee == b->body.monitor.holder) {
	register struct execution_environment *new;
	assert(b->body.monitor.reentry_depth > 0);
	if (--b->body.monitor.reentry_depth == 0) {
	    b->body.monitor.holder = 0;
	    if (new = b->body.monitor.first) {
		b->body.monitor.first = new->next;
		new->next = 0;
		assert(new->event == monitor_wait);
		new->event = 0;
		enqueue_process(new);
	    }
	}
	decref(b);
    }
    else if (ee->event == monitor_wait) {
	assert(body_of(&ee->pos->env.monitor) == b);
	if (b->body.monitor.first == ee) {
	    b->body.monitor.first = ee->next;
	    ee->next = 0;
	}
	else {
	    register struct execution_environment *where;
	    for (where = b->body.monitor.first;
		    where && where->next != ee;
		    where = where->next);
	    assert(where);
	    where->next = ee->next;
	    ee->next = 0;
	    if (ee = b->body.monitor.last)
		b->body.monitor.last = where;
	}
	decref(b);
    }
}

initialize_monitor()
{
    define_operator("createmonitor", createmonitor, 0, 0, 1);
    define_operator("monitorlocked", monitorlocked, 0, 1, 1);
}