.TITLE	TICMRK - ROUTINE TO PLOT TIC MARKS(LOW LEVEL)

.IDENT	'TICM00'

.PSECT	TICMRK

;	THIS ROUTINE IS A LOW LEVEL ROUTINE USED TO
;	PLOT TIC MARKS. IT ALWAYS STARTS TICS AT THE
;	ORIGIN. A ROW OF X TICS ARE PLOTTED. THEN THE
;	Y COORDINATE IS CHANGED(ACCORDING TO YSPACE
;	VALUE) AND ANOTHER ROW OF TICKS IS PLOTTED.

;	ON ENTRY:

;	R0 = X COORDINATE OF Y GRID
;	R1 = Y COORDINATE OF X GRID
;	R2 = X SPACING
;	R3 = Y SPACING

;	INTERNAL GLOBALS

.GLOBL	T$ICMRK

;	EXTERNAL GLOBALS

.GLOBL	P$LTTIC,X$MAXCO,Y$MAXCO
.GLOBL	R$IDGX,R$IDGY




T$ICMRK: MOV	R0,R4		;R4= X COORDINATE FOR NEXT TIC
	MOV	R1,R5		;R5= Y COORDINATE FOR NEXT TIC
	CMP	#R$IDGX,R4	;WITHIN MIN?
	BGT	TIC30		;NO
	CMP	#R$IDGY,R5	;WITHIN MIN?
	BGT	TIC30		;NO
TIC10:	CALL	P$LTTIC		;PLOT A TIC MARK
	ADD	R2,R4		;SPACE ALONG X AXIS
	CMP	#X$MAXCO,R4	;OFF SCREEN YET?
	BLT	TIC20		;YES
	CMP	#R$IDGX,R4	;LEFT OF MIN YET?
	BLE	TIC10		;NO
TIC20:	MOV	R0,R4		;INIT X POSITION
	ADD	R3,R5		;SPACE ALONG Y AXIS
	CMP	#Y$MAXCO,R5	;OFF SCREEN YET?
	BLT	TIC30		;YES
	CMP	#R$IDGY,R5	;BELOW MIN YET?
	BLE	TIC10		;NO
TIC30:	RETURN
	.END