* = $801

a = 8000
b = 8004
rs = 8006	;decimal locations used by basic

byte	$07,$08,$02,$00,$99,$00,$1B,$08,$05,$00,$85,$22,$44,$49,$56,$49,$44,$45,$4E,$44,$3A
byte	$20,$22,$3B,$41,$00,$50,$08,$08,$00,$8B,$41,$B1,$28,$32,$AE,$33,$31,$29,$AB,$31,$B0
byte	$20,$41,$B3,$30,$20,$A7,$20,$99,$20,$22,$56,$41,$4C,$55,$45,$20,$4F,$55,$54,$20,$4F
byte	$46,$20,$52,$41,$4E,$47,$45,$2E,$22,$3A,$99,$3A,$89,$20,$35,$00,$9C,$08,$09,$00,$41
byte	$53,$B2,$B5,$28,$41,$AD,$32,$AE,$32,$34,$29,$3A,$41,$48,$B2,$B5,$28,$28,$41,$AB,$28
byte	$41,$53,$AC,$32,$AE,$32,$34,$29,$29,$AD,$36,$35,$35,$33,$36,$29,$3A,$41,$4D,$B2,$B5
byte	$28,$28,$41,$AB,$28,$41,$53,$AC,$32,$AE,$32,$34,$29,$AB,$41,$48,$AC,$36,$35,$35,$33
byte	$36,$29,$AD,$32,$35,$36,$29,$00,$BF,$08,$0A,$00,$41,$4C,$B2,$28,$41,$AB,$41,$53,$AC
byte	$32,$AE,$32,$34,$AB,$41,$48,$AC,$36,$35,$35,$33,$36,$29,$AB,$41,$4D,$AC,$32,$35,$36
byte	$00,$D3,$08,$14,$00,$85,$20,$22,$44,$49,$56,$49,$53,$4F,$52,$3A,$20,$22,$3B,$42,$00
byte	$0F,$09,$16,$00,$8B,$20,$42,$20,$B1,$20,$28,$32,$AE,$31,$35,$29,$AB,$31,$20,$B0,$20
byte	$42,$B3,$B2,$30,$20,$20,$A7,$20,$99,$20,$22,$56,$41,$4C,$55,$45,$20,$4F,$55,$54,$20
byte	$4F,$46,$20,$52,$41,$4E,$47,$45,$2E,$22,$3A,$99,$3A,$89,$20,$32,$30,$00,$2B,$09,$19
byte	$00,$42,$48,$B2,$B5,$28,$42,$AD,$32,$35,$36,$29,$3A,$42,$4C,$B2,$42,$AB,$32,$35,$36
byte	$AC,$42,$48,$00,$55,$09,$1E,$00,$97,$20,$38,$30,$30,$30,$2C,$41,$53,$3A,$97,$38,$30
byte	$30,$31,$2C,$41,$48,$3A,$97,$20,$38,$30,$30,$32,$2C,$41,$4D,$3A,$97,$38,$30,$30,$33
byte	$2C,$41,$4C,$00,$6D,$09,$28,$00,$97,$20,$38,$30,$30,$34,$2C,$42,$48,$3A,$97,$20,$38
byte	$30,$30,$35,$2C,$42,$4C,$00,$78,$09,$32,$00,$9E,$20,$32,$35,$34,$38,$00,$96,$09,$37
byte	$00,$99,$20,$22,$52,$45,$53,$55,$4C,$54,$20,$4F,$46,$20,$44,$49,$56,$49,$53,$49,$4F
byte	$4E,$20,$22,$3A,$99,$00,$D2,$09,$3C,$00,$99,$20,$22,$4D,$4C,$3A,$20,$22,$3B,$C2,$28
byte	$38,$30,$30,$36,$29,$AC,$32,$AE,$32,$34,$AA,$C2,$28,$38,$30,$30,$37,$29,$AC,$36,$35
byte	$35,$33,$36,$AA,$C2,$28,$38,$30,$30,$38,$29,$AC,$32,$35,$36,$AA,$C2,$28,$38,$30,$30
byte	$39,$29,$00,$EA,$09,$46,$00,$99,$20,$22,$42,$41,$53,$49,$43,$3A,$20,$22,$3B,$41,$AD
byte	$42,$3A,$99,$3A,$99,$00,$F2,$09,$50,$00,$89,$20,$35,$00,$00,$00


; 31 bit by 15 bit divide (two billions etc... maximum value for a, 32767 for b)

		lda	#$00
		sta	rs
		sta	rs+1		;rs = 0
		sta	rs+2
		sta	rs+3
		sta	k
		sta	k+1		;k = 0
		sta	k+2
		sta	k+3

		lda	a
		sta	oa
		lda	a+1
		sta	oa+1		;oa = a
		lda	a+2
		sta	oa+2
		lda	a+3
		sta	oa+3

		lda	a
		bmi	skip_ab_check_close
		lda	b
		bmi	skip_ab_check_close	;exits if b >32767 or a > 2 billions etc...

		jmp	label_40

skip_ab_check_close
		rts

label_40	sec
		lda	a+3
		sbc	k+3
		sta	a+3
		lda	a+2
		sbc	k+2
		sta	a+2
		lda	a+1
		sbc	k+1
		sta	a+1
		lda	a
		sbc	k
		sta	a		;a = a-k

		lda	a
		cmp	#$00
		bcc	label_50
		bne	label_48
		lda	a+1
		cmp	#$00
		bcc	label_50
		bne	label_48
		lda	a+2
		cmp	b
		bcc	label_50
		bne	label_48
		lda	a+3
		cmp	b+1
		bcc	label_50	;if a < b then goto 50

label_48	jsr	routine_1000

		clc
		lda	rs+3
		adc	q+3
		sta	rs+3
		lda	rs+2
		adc	q+2
		sta	rs+2
		lda	rs+1
		adc	q+1
		sta	rs+1
		lda	rs
		adc	q
		sta	rs		;rs=rs+q

		jmp	label_40
		
label_50	lda	a
		cmp	#$00
		bne	skip_ab_check
		lda	a+1
		cmp	#$00
		bne	skip_ab_check
		lda	a+2
		cmp	b
		bne	skip_ab_check
		lda	a+3
		cmp	b+1
		beq	inc_rs_low	;if a = b then rs = 1

skip_ab_check	rts

inc_rs_low	inc	rs+3
		rts


routine_1000	
		lda	#$00
		sta	k
		lda	#$00
		sta	k+1
		lda	b
		sta	k+2
		lda	b+1
		sta	k+3		;k = b


		lda	b
		bne	skip_b_0_check
		lda	b+1
		beq	end		;return to caller of main program if b = 0

		
		
skip_b_0_check	lda	#$00
		sta	ct		;ct = 0

label_1010	
		asl	k+3
		rol	k+2
		rol	k+1
		rol	k		;k = k * 2

		lda	k+3
		bne	skip_check_k

		lda	k+2
		bne	skip_check_k

		lda	k+1
		bne	skip_check_k

		lda	k
		beq	end		;if k = 0 (low and hi byte) then return to caller of main program
					;overflow condition

skip_check_k	lda	k
		cmp	a
		bcc	inc_ct
		bne	label_1020
		lda	k+1
		cmp	a+1
		bcc	inc_ct
		bne	label_1020
		lda	k+2
		cmp	a+2
		bcc	inc_ct
		bne	label_1020
		lda	k+3
		cmp	a+3
		bcc	inc_ct


label_1020	lsr	k
		ror	k+1
		ror	k+2
		ror	k+3		;a = a/2

		ldx	ct
		lda	power,x
		sta	q
		inx
		lda	power,x
		sta	q+1
		inx
		lda	power,x
		sta	q+2
		inx	
		lda	power,x
		sta	q+3

		; q = 2 ^ ct

		rts	

end		pla
		pla
		rts

inc_ct		inc	ct
		inc	ct
		inc	ct
		inc	ct		;four times because power table is 32 bit
		jmp	label_1010

power		byte	0,0,0,1,0,0,0,2,0,0,0,4,0,0,0,8,0,0,0,16,0,0,0,32,0,0,0,64,0,0,0,128
		byte	0,0,1,0,0,0,2,0,0,0,4,0,0,0,8,0,0,0,16,0,0,0,32,0,0,0,64,0,0,0,128,0
		byte	0,1,0,0,0,2,0,0,0,4,0,0,0,8,0,0,0,16,0,0,0,32,0,0,0,64,0,0,0,128,0,0
		byte	1,0,0,0,2,0,0,0,4,0,0,0,8,0,0,0,16,0,0,0,32,0,0,0,64,0,0,0,128,0,0,0
		

ct		byte	0
q		byte	0,0,0,0
k		byte	0,0,0,0
oa		byte	0,0,0,0
;a		byte	0,0,0,0
;b		byte	0,0
;rs		byte	0,0,0,0