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    Length: 3523 (0xdc3)
    Types: TextFile
    Names: »cvmove.c«

└─⟦b20c6495f⟧ Bits:30007238 EUUGD18: Wien-båndet, efterår 1987
    └─⟦this⟧ »EUUGD18/General/Crystal/cvmove.c« 

TextFile

/* cvmove.c
 *   various object motion subroutines
 *************************************************************************/

#include <stdio.h>
#include "cvobj.h"
#include "cvlocs.h"

extern void bug() ;
extern int holding ;

/* start toting an object, removing it from the list of things at its
 * former location.  Increment 'holding' unless it was already being
 * toted.
 * Primarily used by move().
 */
void
carry(obj) register struct cvobj *obj;
{	register struct cvloc *from;
	register struct conn *this;

	from = obj->conn1.where ;
	obj->conn1.where = TAKEN ;
	if (from == TAKEN) return ;
	++holding ;
	if (from != (struct cvloc *) NULL)
	{	for ( this = &(from->atloc);
			this->link != &(obj->conn1); this = this->link)
			if (this->link == NULL) bug(30);
		this->link = obj->conn1.link ;
	}
	obj->conn1.link = NULL ;
	return;
}

/* pick up an object by its second location, removing it from the list
 * of things at its former location.
 * Primarily used by move2().
 */
static void
carry2(obj) register struct cvobj *obj;
{	register struct cvloc *from;
	register struct conn *this;

	from = obj->conn2.where ;
	obj->conn2.where = TAKEN ;
	if (from == TAKEN) return ;
	if (from != (struct cvloc *) NULL)
	{	for ( this = &(from->atloc);
			this->link != &(obj->conn2); this = this->link)
			if (this->link == NULL) bug(30);
		this->link = obj->conn2.link ;
	}
	obj->conn2.link = NULL ;
	return;
}
\f


/* place any object anywhere by picking it up and dropping it.
 * may already be toting it, in which case the carry is a no-op.
 *
 * to move the second place of an object, use the object's number plus
 * OBJSIZ as the object.
 *
 * 'move' may be called regardless of where the object was, whether
 * it's being carried, is lost, is destroyed, or whatever.
 */
void
move(obj,toloc)
	register struct cvobj *obj;
	register struct cvloc *toloc;
{
	register struct cvloc *from;

	from = obj->conn1.where ;
	if ((from != LOST) && (from != TAKEN)) carry(obj);

	if (obj->conn1.where == TAKEN) --holding ;
	obj->conn1.where = toloc ;
	if (toloc == LOST) return ;
	obj->conn1.link = toloc->atloc.link ;
	toloc->atloc.link = &(obj->conn1) ;
	return;
}

/* place any object anywhere by picking it up and dropping it by its
 * second location.  May already be toting it, in which case the carry
 * is a no-op.
 *
 * 'move2' may be called regardless of where the object was, whether
 * it's being carried, is lost, is destroyed, or whatever.
 */
void
move2(obj,toloc)
	register struct cvobj *obj;
	register struct cvloc *toloc;
{
	register struct cvloc *from;

	from = obj->conn2.where ;
	if ((from != LOST) && (from != TAKEN)) carry2(obj);

	if (obj->conn2.where == TAKEN) --holding ;
	obj->conn2.where = toloc ;
	if (toloc == LOST) return ;
	obj->conn2.link = toloc->atloc.link ;
	toloc->atloc.link = &(obj->conn2) ;
	return;
}


/* juggle an object by picking it up and putting it down again, the
 * purpose being to get the object to the front of the chain of things
 * at its location.
 */
void
juggle(obj) register struct cvobj *obj;
{
	register struct cvloc *where;

	where = obj->conn1.where ;
	if (where == NULL) bug(33);
	move(obj,where);
	return;
}

void
juggl2(obj) register struct cvobj *obj;
{	register struct cvloc *where;

	where = obj->conn2.where ;
	if (where == NULL) bug(33);
	move2(obj,where);
	return;
}


/* destroy the object by dropping at an inaccessable place
 */
void
destry(obj) register struct cvobj *obj;
{	move(obj,LOST);
}

void
destr2(obj) register struct cvobj *obj ;
{	move2(obj,LOST);
}