Intel 210200-002 manual Register Usage

APPENDIX

BENCHMARK: Block Move

PROCESSOR: Motorola 6809

;REGISTER USAGE

D - Block Length

X - Temporary Storage

Y - Source Pointer

U - Destination Pointer

Bytes	Cycles
4	4	LDY	#FROM			;Initialize		Source Pointer
3	3	LDU	#TO			;Initialize		Destination Pointer
3	3	LDD	#LENGTH			:Initialize		Block Length
1	2	INCB
2	3	BNC	SHIFT			;Add one to avoid losing a
1	2	INCA				; byte if LENGTH is odd
1	2 SHIFT	LSRA				;Adjust LENGTH for word
1	2	RORB	,Y++			; moves
2	8 MOVE	LDX				;Read word
2	8	STX	,U++			;Store word
1	2	DECB	MOvE			;LS	Count
2	3	BNE
1	2	DECA	MOvE			;MS	Count
2	3	BNE
		26	bytes	of	code
		14	1ines	of	code

33 AFN 01532A