The AAD
instruction is invalid in 64-bit mode, but its operation is described in Intel's Software Developer's Manual, so you can implement the same functionality yourself if you need it:
tempAL ← AL;
tempAH ← AH;
AL ← (tempAL + (tempAH ∗ imm8)) AND FFH;
(* imm8 is set to 0AH for the AAD mnemonic.*)
AH ← 0;
The SF, ZF, and PF flags are set according to the resulting binary value in the AL register; the OF, AF, and CF flags are undefined.