HCS12 datasheet(161/452 Pages) FREESCALE

161 / 452 page

S12CPUV2 Reference Manual, Rev. 4.0

Freescale Semiconductor

161

Description:

DAA adjusts the content of accumulator A and the state of the C status bit

to represent the correct binary-coded-decimal sum and the associated carry

when a BCD calculation has been performed. To execute DAA, the content

of accumulator A, the state of the C status bit, and the state of the H status

bit must all be the result of performing an ABA, ADD, or ADC on BCD

operands, with or without an initial carry.

The table shows DAA operation for all legal combinations of input operands.

Columns 1 through 4 represent the results of ABA, ADC, or ADD operations

on BCD operands. The correction factor in column 5 is added to the

accumulator to restore the result of an operation on two BCD operands to a

valid BCD value and to set or clear the C bit. All values are in hexadecimal.

DAA

Decimal Adjust A

DAA

1234

Initial

C Bit Value

Value

of A[7:4]

Initial

H Bit Value

Value

of A[3:0]

Correction

Factor

Corrected

C Bit Value

0–9

0–8

A–F

0–9

0–3

A–F

0–9

9–F

A–F

0–3

0–2

0–9

0–2

A–F

0–3

CCR Details:

HIN

––––

∆∆

∆

N: Set if MSB of result is set; cleared otherwise

Z: Set if result is $00; cleared otherwise

V: Undefined

C: Represents BCD carry. See bit table

Source Form

Address

Mode

Object Code

Access Detail

HCS12

M68HC12

DAA

INH

18 07

OfO

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