AAS              ASCII Adjust after Subtraction      Flags: O D I T S Z A P C

?       ? ? * ? *

AAS

Logic:    If (AL & 0Fh) > 9 or AF = 1 then

AL   AL - 6

AH   AH - 1

AF   1;  CF   1

else

AF   0;  CF   0

AL   AL & 0Fh

AAS corrects the result of a previous subtraction of two valid

unpacked BCD operands, changing the content of AL to a valid BCD

number. The destination operand of the subtraction must have been

specified as AL. The high-order nibble of AL is always set to 0.

Operands                  Clocks   Transfers  Bytes   Example

no operands                 4          -        1     AAS

Note:          Unpacked BCD stores one digit per byte; AH contains

the most-significant digit and AL the least-

significant digit.

Prev:     AAM ASCII Adjust after Multiply

See also: AAA

See also: AAD

See also: AAS

See also: SUB

See also: SBB

See also: DAS

See also: Flags

Next:     ADC Add with Carry