AT89LP6440 datasheet(151/194 Pages) ATMEL

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3706A–MICRO–9/09

AT89LP6440 - Preliminary

22.1.9

MAC AB

Function: Multiply and Accumulate

Description: MAC AB multiplies the signed 16-bit integers in the register pairs {AX, A} and {BX, B} and adds the 32-bit product

to the 40-bit M register. The low-order bytes of the 16-bit operands are stored in A and B, and the high-order

bytes in AX and BX respectively. The four operand registers are unaffected by the operation. If the addition of the

product to the accumulated sum in M results in a two's complement overflow, the overflow flag is set; otherwise it

is not cleared. The carry flag is set if the result is negative and cleared if positive.

Example: Originally the Accumulator holds the value 80 (50H). Register B holds the value 160 (0A0H). The instruction,

MAC AB

will give the product 12, 800 (3200H), so B is changed to 32H (00110010B) and the Accumulator is cleared. The

overflow flag is set, carry is cleared.

Bytes: 2

Cycles: 9

Encoding:

010

Operation: MAC

39-0) ← (M) + { (AX), (A) } X { (BX), (B) }

22.1.10

MOV /DPTR, #data16

Function: Load Alternate Data Pointer with a 16-bit constant

Description: MOV /DPTR, #data16 loads the unselected Data Pointer with the 16-bit constant indicated. The third byte is the

high-order byte, while the fourth byte holds the lower-order byte. No flags are affected.

Example: When DPS = 0, the instruction sequence,

MOV

DPTR, # 1234H

MOV /DPTR, # 5678H

loads the value 1234H into the first Data Pointer: DPH0 holds 12H and DPL0 holds 34H; and loads the value

5678H into the second Data Pointer: DPH1 hold 56H and DPL1 holds 78H.

Bytes: 2

Cycles: 3

Encoding:

immed. data 15-8

immed. data 7-0

Operation: MOV

IF (DPS) = 0

THEN

(DP1H)

← #data

15-8

(DP1L)

← #data

7-0

ELSE

(DP0H)

← #data

15-8

(DP0L)

← #data

7-0

AT89LP6440 Datasheet(PDF) 151 Page - ATMEL Corporation

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