TITLE	"mp3.a by Douglas Jones"
;       subroutine to do preorder traversal
;       note that this code is deliberately
;       written to a fairly low level of
;       optimization
 
	USE	"hawk.h"
	USE	"monitor.h"

	INT	TRAVERSE

; format of one tree node
VALUE	=	0
CHILD	=	4

; activation record for TRAVERSE
; retad	=	0
P  	=	4	; the parameter, points to a node
I  	=	8	; loop counter
ARSIZE 	=	12

TRAVERSE:	; expects, R3 = p
	STORES	R1,R2
	STORE	R3,R2,P		; -- save parameter

	LIS	R3,0
	STORE   R3,R2,I		; i = 0

	LOAD	R3,R2,P
	LOAD	R3,R3,VALUE	; -- parameter
	ADDI	R2,R2,ARSIZE
	LIL	R1,PUTS
	JSRS	R1,R1		; puts( p->value )
	ADDI	R2,R2,-ARSIZE

LOOP:				; loop {
	LOAD	R3,R2,P
	LEA	R4,R3,CHILD	;   -- address of p->child
	LOAD	R5,R2,I
	SL  	R5,2
	ADD 	R6,R5,R4	;   -- address of p->child[i]
	LOADSCC	R3,R6
	BZS	LOOPX		;   if (p->child[i] == NULL) break

	LOAD	R3,R2,P
	LEA	R4,R3,CHILD	;   -- address of p->child
	LOAD	R5,R2,I
	SL  	R5,2
	ADD 	R6,R5,R4	;   -- address of p->child[i]
	LOADS	R3,R6		;   -- parameter
	ADDI	R2,R2,ARSIZE
	JSR	R1,TRAVERSE	;   traverse( p->child[i] )
	ADDI	R2,R2,-ARSIZE

	LOAD	R3,R2,I
	ADDSI	R3,1
	STORE	R3,R2,I		;   i = i + 1

	BR	LOOP		; }
LOOPX:

	LOADS	R1,R2
	JUMPS	R1		; return
	END