Intel 80C186XL User Manual page 334

Name
CWD Convert Word to Doubleword:
CWD
Extends the sign of the word in register
AX throughout register DX. Use to
produce a double-length (doubleword)
dividend from a word prior to
performing word division.
Instruction Operands:
none
DAA Decimal Adjust for Addition:
DAA
Corrects the result of previously
adding two valid packed decimal
operands (the destination operand
must have been register AL). Changes
the content of AL to a pair of valid
packed decimal digits.
Instruction Operands:
none
DAS Decimal Adjust for Subtraction:
DAS
Corrects the result of a previous
subtraction of two valid packed
decimal operands (the destination
operand must have been specified as
register AL). Changes the content of
AL to a pair of valid packed decimal
digits.
Instruction Operands:
none
NOTE: The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed
ü
the flag is updated after the instruction is executed
Table C-4. Instruction Set (Continued)
Description
INSTRUCTION SET DESCRIPTIONS
Operation
if
(AX) < 8000H
then
(DX) 0
else
(DX) FFFFH
if
((AL) and 0FH) > 9 or (AF) = 1
then
(AL) (AL) + 6
(AF) 1
if
(AL) > 9FH or (CF) = 1
then
(AL) (AL) + 60H
(CF) 1
if
((AL) and 0FH) > 9 or (AF) = 1
then
(AL) (AL) – 6
(AF) 1
if
(AL) > 9FH or (CF) = 1
then
(AL) (AL) – 60H
(CF) 1
Flags
Affected
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
ü
AF
ü
CF
DF –
IF –
OF ?
ü
PF
ü
SF
TF –
ü
ZF
ü
AF
ü
CF
DF –
IF –
OF ?
ü
PF
ü
SF
TF –
ü
ZF
C-11