Intel 210200-002 manual Addd

APPENDIX

BENCHMARK: l6-Bit Multiply

PROCESSOR: Motorola 6809

;REGISTER	USAGE:
D -	ACCUMULATOR
X -	OPERAND	POINTER
Y -	OPERAND	POINTER
U -	PRODUCT	POINTER

Bytes

Cycles

3

3

LDX

#M

;Pointer to multiplicand A(MS Byte)

4

5

LDY

#BB

;Pointer to multiplicand B(MS Byte)

3

3

LDU

#MO

;Pointer

to product

~

6

CLR

O,U

;CLR

MO

~

6

CLR

1,U

;CLR

Ml

~

5

LDA

1,X

;Read

LS

byte

of

A (AL)

~

5

LDB

1, Y

;Read

LS

byte

of

B (BL)

1

11

MUL

;AL*BL

~

6

STD

2,U

;Store

in

M3:M2

~

4

LDA

O,X

;Read MS byte of A (AH)

~

5

LDB

1,Y

;Read LS byte of B (BL)

1

11

MUL

1,U

;AH*BL

~

7

ADDD

;AH*BL + MS byte from AL*BL

~

6

STD

1,U

;Store

in

M2:Ml

~

3

BCC

ABl

;Skip INC if no carry

~

6

INC

O,U

;Add

carry to

MO

~

5

ABl

LDA

1,X

;Read

LS

byte

of

A (AL)

~

4

LDB

O,Y

;Read LS byte of B (BH)

1

11

MUL

1,U

;AL*BH

~

7

ADDD

;AL*BH+ M2:Ml

2

6

STD

1,U

;Store

in

M~:Ml

~

3

BCC

AB2

;Skip INC if no carry

~

6

INC

O,U

;Add

carry to

MO

~

4 AB~

LDA

O,X

;Read

AH

~

4

LDB

O,Y

;Read

BH

1

11

MUL

O,U

;AH*BH

+Ml + carries

2

7

ADDD

;AH*BH

~

6

STD

O,U

;Store

in

Ml :MO

56

bytes

of

code

28

lines

of

code

30 AFN 01532A