.TITLE	TICMKG - ROUTINE TO PLOT TICS ALONG GRID

.IDENT	'TMKG00'

.PSECT	TMKG00

;	KEN DEMERS
;	UTRC
;	NOVEMBER 1979

;	THIS IS THE LOW LEVEL ROUTINE TO PLOT
;	TIC MARKS ONLY ALONG THE X AND Y GRID.

;	ON ENTRY:

;	R0 = ORIGIN'S X COORDINATE
;	R1 = ORIGIN'S Y COORDINATE
;	R2 = SPACING BETWEEN TICS

;	INTERNAL GLOBALS

.GLOBL	T$ICMKG,M$IN,M$AX,C$HNG,X$ORY
.GLOBL	P$LTTIC



T$ICMKG: TST	-(SP)		;SAVE ROOM ON SP
TIC10:	MOV	R0,R4		;R4= X COORD
	MOV	C$HNG,(SP)	;SP= CHANGING COORD
	MOV	R1,R5		;R5= Y COORD
TIC20:	CALL	P$LTTIC		;PLOT A TIC MARK
	ADD	R2,(SP)		;POSITION TO NEXT TIC
	CMP	M$AX,(SP)	;< MAX?
	BLT	TIC40		;NO
	CMP	M$IN,(SP)	;> MIN?
	BGT	TIC40		;NO
	TST	X$ORY		;X OR Y GRID TICS?
	BEQ	TIC30		;X
	MOV	(SP),R5		;BUMP Y COORD
	BR	TIC20
TIC30:	MOV	(SP),R4		;BUMP X COORD
	BR	TIC20		;PLOT NEXT TIC ON GRID
TIC40:	NEG	R2		;DONE 2ND 1/2 OF GRID?
	BMI	TIC10		;NO
	TST	(SP)+		;RETORE SP TO ORIG POSITION
	RETURN

M$IN:	.WORD	0		;GRID MIN
M$AX:	.WORD 	0		;GRID MAX
C$HNG:	.WORD	0		;ORIGIN VALUE OF COORD THAT CHANGES
X$ORY:	.WORD	0		;X OR Y FLG 0=X  1=Y
	.END