Apple II manual Normx BCC Norm If EXEN, Normalize PRODUCT, Else Complement

1F8D	90	AF	NORMX	BCC NORM	IF EXEN, NORMALIZE PRODUCT, ELSE COMPLEMENT
1F8F	38		FCOMPL SEC		SET CARRY FOR SUBTRACT
1F90	A2	03		LDX =$03	INDEX FOR 3 BYTE SUBTRACTION
1F92	A9	00	COMPL1	LDA =$00	CLEAR A
1F94	F5	08		SBC X1,X	SUBTRACT BYTE OF EXP1
1F96	95	08		STA X1,X	RESTORE IT
1F98	CA			DEX	NEXT MORE SIGNIFICANT BYTE
1F99	D0	F7		BNE COMPL1	LOOP UNTIL DONE
1F9B	F0	BC	*	BEQ ADDEND	NORMALIZE (OR SHIFT RIGHT IF OVERFLOW)
			*

*EXP/MANT2 / EXP/MANT1 RESULT IN EXP/MANT1

1F9D	20	0D	1F	FDIV	JSR MD1	TAKE ABS VAL OF MANT1, MANT2
1FA0	E5	08			SBC X1	SUBTRACT EXP1 FROM EXP2
1FA2	20	CD 1F			JSR MD2	SAVE AS QUOTIENT EXP
1FA5	38			DIV1	SEC	SET CARRY FOR SUBTRACT
1FA6	A2	02			LDX =$02	INDEX FOR 3-BYTE INSTRUCTION
1FA8	B5	05		DIV2	LDA M2,X
1FAA	F5	0C			SBC E,X	SUBTRACT A BYTE OF E FROM MANT2
1FAC	48				PHA	SAVE ON STACK
1FAD	CA				DEX	NEXT MORE SIGNIF BYTE
1FAE	10	F8			BPL DIV2	LOOP UNTIL DONE
1FB0	A2	FD			LDX =$FD	INDEX FOR 3-BYTE CONDITIONAL MOVE
1FB2	68			DIV3	PLA	PULL A BYTE OF DIFFERENCE OFF STACK
1FB3	90	02			BCC DIV4	IF MANT2<E THEN DONT RESTORE MANT2
1FB5	95	08			STA M2+3,X
1FB7	E8			DIV4	INX	NEXT LESS SIGNIF BYTE
1FB8	D0	F8			BNE DIV3	LOOP UNTIL DONE
1FBA	26	0B			ROL M1+2
1FBC	26	0A			ROL M1+1	ROLL QUOTIENT LEFT, CARRY INTO LSB
1FBE	26	09			ROL M1
1FC0	06	07			ASL M2+2
1FC2	26	06			ROL M2+1	SHIFT DIVIDEND LEFT
1FC4	26	05			ROL M2
1FC6	B0	1C			BCS OVFL	OVERFLOW IS DUE TO UNNORMALIZED DIVISOR
1FC8	88				DEY	NEXT DIVIDE ITERATION
1FC9	D0	DA			BNE DIV1	LOOP UNTIL DONE 23 ITERATIONS
1FCB	F0	BE			BEQ MDEND	NORMALIZE QUOTIENT AND CORRECT SIGN
1FCD	86	0B		MD2	STX M1+2
1FCF	86	0A			STX M1+1	CLR MANT1 (3 BYTES) FOR MUL/DIV
1FD1	86	09			STX M1
1FD3	B0	0D			BCS OVCHK	IF EXP CALC SET CARRY, CHECK FOR OVFL
1FD5	30	04			BMI MD3	IF NEG NO UNDERFLOW
1FD7	68				PLA	POP ONE
1FD8	68				PLA	RETURN LEVEL
1FD9	90	B2			BCC NORMX	CLEAR X1 AND RETURN
1FDB	49	80		MD3	EOR =$80	COMPLIMENT SIGN BIT OF EXP
1FDD	85	08			STA X1	STORE IT
1FDF	A0	17			LDY =$17	COUNT FOR 24 MUL OR 23 DIV ITERATIONS
1FE1	60				RTS	RETURN
1FE2	10	F7		OVCHK	BPL MD3	IF POS EXP THEN NO OVERFLOW
1FE4	00			OVFL	BRK
				*
				*

*CONVERT EXP/MANT1 TO INTEGER IN M1 (HIGH) AND M1+1(LOW)

*EXP/MANT2 UNEFFECTED

			*
1FE5	20	5F	1F	JSR RTAR	SHIFT MANT1 RT AND INCREMENT EXPNT
1FE8	A5	08	FIX	LDA X1	CHECK EXPONENT
1FEA	C9	8E		CMP =$8E	IS EXPONENT 14?
1FEC	D0	F7		BNE FIX-3	NO, SHIFT