.TITLE DIFTIM
;
;	TESTPROGRAM TO CALCULATE THE TIME DIFFERENCE IN HH,MM,SS BETWEEN
;	2 TIME-ARRAYS ("LOGIN" AND "LOGOUT")
;
	.MCALL GTIM$S
;
;
DIFTIM:	MOV #LOGIN,R0
	MOV #LOGOUT,R1
	BIT #3,(R0)		;LOGIN IN "LEAP-YEAR"?
	BNE 1$			;IF NE NO
	CMP #3,2(R0)		;LOGIN BEFORE MARCH?
	BLE 2$			;IF LE NO
	INC TAB+2		;MAKE #DAYS IN FEB = 29.
	BR 2$
1$:	BIT #3,(R1)		;LOGOUT IN "LEAP-YEAR"?
	BNE 2$			;IF NE NO
	CMP #3,2(R1)		;LOGOUT AFTER FEBR.?
	BLE 2$			;IF LE YES
	INC TAB+2		;MAKE #DAYS IN FEB = 29.
2$:	CLR R2
	MOV (R1)+,R4		;GET LOGOUT YEAR
	SUB (R0)+,R4		;SUBTRACT LOGIN YEAR
	BEQ NEXT1		;IF EQ NO FIREWORKS IN BETWEEN
	MOV #12.,R2		;ADD 12 MONTHS LATER ON
;
NEXT1:	MOV (R1)+,R4		;GET LOGOUT MONTHS
	ADD R2,R4		;ADD 0 OR 12
	CLR R2
	MOV (R0)+,R3		;SUBTRACT LOGIN MONTHS
	SUB R3,R4
	BEQ NEXT2		;IF EQ DON'T ADD DAYS
	DEC R3			;PREPARE POINTER TO TAB
	ASL R3
ADDTAB:	ADD TAB(R3),R2		;ADD DAYS LATER ON
	INC R3			;UPDATE POINTER
	INC R3
	CMP #22.,R3		;PAST DECEMBER??
	BGE 10$			;IF GE NO
	CLR R3			;POINT TO JANUARY AGAIN
10$:	DEC R4			;ALL DONE?
	BGT ADDTAB		;IF GT NO
;
NEXT2:	MOV (R1)+,R4		;GET LOGOUT DAYS
	ADD R2,R4		;ADD NUMBER OF DAYS
	CLR R3
	SUB (R0)+,R4		;SUBTRACT LOGIN DAYS
	BEQ NEXT3		;IF EQ DON'T ADD HOURS LATER ON
	MOV R4,R3
	MUL #24.,R3		;R3 = NUMBER OF HOURS TO ADD
;
NEXT3:	MOV (R1)+,R4		;GET LOGOUT HOURS
	ADD R3,R4		;ADD SOME
	SUB (R0)+,R4		;SUBTRACT LOGIN HOURS
	MOV R4,DIFHH		;SAVE NUMBER OF HOURS CONNECTED TO SYSTEM
;
;
	MOV (R1)+,R4		;GET LOGOUT MINUTES
	SUB (R0)+,R4		;SUBTRACT LOGOUT MINUTES
	BEQ NEXT5		;IF EQ NO ACTION
	DEC DIFHH		;TAKE 60 MINUTES AND
	ADD #60.,R4		;ADD THEM TO MINUTE COUNTER
NEXT5:	MOV R4,DIFMM		;SAVE MINUTES
	MOV (R1),R4		;GET LOGOUT SECONDS
	SUB (R0),R4		;SUBTRACT LOGIN SECONDS
	BEQ NEXT6		;IF EQ NO ACTION
	DEC DIFMM		;TAKE 60 SECONDS AND
	ADD #60.,R4		;ADD THEM TO SECOND COUNTER
	MOV R4,DIFSS		;SAVE SECONDS
NEXT6:	CLR R4			;#SECONDS SHOULD BE < 60
	MOV DIFSS,R5
	DIV #60.,R4
	MOV R5,DIFSS
	ADD R4,DIFMM
	CLR R4			;# MINUTES TOO
	MOV DIFMM,R5
	DIV #60.,R4
	MOV R5,DIFMM
	ADD R4,DIFHH
	MOV DIFHH,R0		;SHOW COUNTERS
	MOV DIFMM,R1
	MOV DIFSS,R2
	TRAP
;
;
DIFHH:	.WORD 0
DIFMM:	.WORD 0
DIFSS:	.WORD 0
LOGIN:	.WORD 84.,1,1,0,0,0		!YY,MM,DD,HH,MM,SS
LOGOUT:	.WORD 84.,12.,31.,23.,59.,59.	!YY,MM,DD,HH,MM,SS
TAB:	.WORD 31.,28.,31.,30.,31.,30.,31.,31.,30.,31.,30.,31.
	.END DIFTIM