.TITLE	VIRABS - ROUTINE TO CONVERT VIRT # TO ABS INTEGER

.IDENT	'VITA00'

.PSECT	VIRABS

;	KEN DEMERS
;	UTRC
;	NOVEMBER 1979

;	THIS ROUTINE CONVERTS A F.P. VIRTUAL NUMBER
;	TO A ABSOLUTE INTEGER SCREEN COORDINATE. THE
;	CONVERSION IS DONE USING THE COORDINATE SYSTEM
;	(WINDOW) ESTABLISHED BY GRID

;	ON ENTRY:

;	AC0	= F.P. OF ABSOLUTE INTEGER MAX
;	AC1	= F.P. OF MAX RANGE
;	R0	= A(VIRTUAL F.P. # TO BE CONVERTED)

;	INTERNAL GLOBALS

.GLOBL	V$IRABS


;	ASSIGNMENTS

AC0	= 0			;FPP ACCUMULATOR 0
AC1	= 1
AC2	= 2



V$IRABS: MULF	(R0),AC0	;VIRT # * MAX OF AXIS
	STF	AC1,RANGE	;GET RANGE
	CFCC			;GET COND CODES
	BGE	VIR10		;RANGE WAS POS
	NEGF	RANGE		;MAKE IT POS
VIR10:	DIVF	RANGE,AC0	;GET ABS #
	STCFI	AC0,R0		;ON EXIT R0= INT OF RESULT
	RETURN

RANGE:	.WORD	0,0		;F.P. RANGE
	.END