BlitzDec:
; Define these (preferably on zero page):
;
;  number   16  [input] The number to convert
;
;  digit0    8  Used internally
;  digit1    8   "    "
;  digit2    8   "    "
;  digit3    8   "    "
;  temp      8   "    "
;  temp2     8   "    "
	lda	number
	pha
	and	#$0F
	sta	digit0
	pla
	lsr	a
	lsr	a
	lsr	a
	lsr	a
	sta	digit1
	lda	number+1
	pha
	and	#$0F
	sta	digit2
	pla
	lsr	a
	lsr	a
	lsr	a
	lsr	a
	sta	digit3
	
	clc
	adc	digit2
	adc	digit1
	sta	temp
	asl	a
	adc	temp
	asl	a
	rol	temp2
	adc	digit0
	php
	sta	digit0
	jsr	Div10A
	sta	temp
	
	asl	a
	asl	a
	adc	temp
	asl	a
	sbc	digit0
	eor	#$FF
	plp
	bcs	Fix
	lsr	temp2
	bcc	DontFix

Fix:
	pha
	lda	temp
	adc	#5
	sta	temp
	pla
	adc	#25
DontFix:
	pha			; stack digit0
	
	lda	digit3
	asl	digit3
	asl	digit3
	adc	digit3
	adc	digit3
	sta	temp2
	lda	digit2
	asl	digit2
	adc	digit2
	adc	digit2
	adc	temp2
	adc	temp
	adc	digit1
	sta	digit1
	
	jsr	Div10A
	sta	temp
	asl	a
	asl	a
	adc	temp
	asl	a
	sbc	digit1
	eor	#$FF
	pha			; stack digit1
	
	lda	digit2
	sta	temp2
	lda	temp
	jsr	Div10B
	pha			; stack digit2
	
	lda	digit3
	sta	temp2
	lda	temp
	jsr	Div10B
	pha			; stack digit3
	
; Display digits here. temp, pla, pla, pla, pla
	rts

Div10A:
	sta	temp
	lsr	a
	lsr	a
	clc
	adc	temp
	ror	a
	clc
	adc	temp
	ror	a
	lsr	a
	lsr	a
	clc
	adc	temp
	ror	a
	clc
	adc	temp
	ror	a
	lsr	a
	lsr	a
	lsr	a
	rts
	
Div10B:
	clc
	adc	temp2
	sta	temp2
	lsr	a
	lsr	a
	clc
	adc	temp2
	lsr	a
	clc
	adc	temp2
	lsr	a
	lsr	a
	lsr	a
	lsr	a
	sta	temp
	asl	a
	asl	a
	adc	temp
	asl	a
	sbc	temp2
	eor	#$FF
	rts