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DAS
DECIMAL ADJUST
FOR SUBTRACTION
Operation:
if
«AL) &
OFH)
>9
or (AF) = 1 then
(AL)
+-
(AL) - 6
(A
F)
-1
if (AL) > 9FH
or
(CF) = 1
then
(AL) - (AL) -
60H
(CF)
-1
Description:
DAS (Decimal Adjust for Subtraction) cor-
rects the result of a previous subtraction
of
two valid packed decimal operands (the desti-
nation operand must have
beenspt;cified as
register AL). DAS changes the content of AL
to a pair of valid packed decimal digits. DAS
updates AF. CF.
PF.
SF
and ZF; the content
of
OF
is
undefined following execution of
DAS.
Encoding:
1001011111
Flags Affected:
AF, CF, PF, SF, ZF.
OF
undefined
DAS
DAS Operands Clocks Transfers Bytes DAS Coding Example
(no operands)
4 - 1 DAS
2-71