The rest of the semantics of DAA
(or AAA
). In full, they are (for DAA
):
IF 64-Bit Mode
THEN
#UD;
ELSE
old_AL ← AL;
old_CF ← CF;
CF ← 0;
IF (((AL AND 0FH) > 9) or AF = 1)
THEN
AL ← AL + 6;
CF ← old_CF or (Carry from AL ← AL + 6);
AF ← 1;
ELSE
AF ← 0;
FI;
IF ((old_AL > 99H) or (old_CF = 1))
THEN
AL ← AL + 60H;
CF ← 1;
ELSE
CF ← 0;
FI;
FI;
So you see, it's not just AF that matters, it also checks whether the digit is > 9.