--- xinu/sys/ptclear.c	2018/04/24 17:39:04	1.1.1.1
+++ xinu/sys/ptclear.c	2018/04/24 17:39:48	1.1.1.2
@@ -19,16 +19,19 @@ _ptclear(ptptr, newstate, dispose)
 
 	/* put port in limbo until done freeing processes */
 
+#ifdef	DEBUG
+	dotrace("_ptclear", &ptptr, 3);
+#endif
 	ptptr->ptstate = PTLIMBO;
 	ptptr->ptseq++;
 	if ( (p=ptptr->pthead) != (struct ptnode *)NULL ) {
-		for(; p != (struct ptnode *)NULL ; p=p->ptnext)
+		for(; p != (struct ptnode *) NULL ; p=p->ptnext)
 			(*dispose)( p->ptmsg );
 		(ptptr->pttail)->ptnext = ptfree;
 		ptfree = ptptr->pthead;
 	}
 	if (newstate == PTALLOC) {
-		ptptr->pttail = ptptr->pthead = (struct ptnode *)NULL;
+		ptptr->pttail = ptptr->pthead = (struct ptnode *) NULL;
 		sreset(ptptr->ptssem, ptptr->ptmaxcnt);
 		sreset(ptptr->ptrsem, 0);
 	} else {