AAD

From Asmpedia

ASCII adjust before division

Intel	AMD
+	+

Mode

32	64
+	-

Definition:

Adjusts two unpacked BCD (binary-coded decimal) values in al and ah to a single binary value in al and clears ah:

al += BaseValue*ah, ah = 0; // see pseudo-code below

Operation in pseudo code:

aad(optional imm8 BaseValue)
{
  if (x64)
  {
     throw #UD; // invalid opcode exception 
  }

  if (optional BaseValue)
  {
     BaseValue = 0x0A; // base 10
  }

  al = (al + (ah * BaseValue)) & 0xff;
  ah = 0;
  SF(al);
  ZF(al);
  PF(al); 
}

Opcodes (x86):

D5 0A	base 10
D5 imm8	base imm8

EFLAGS

:31	:30	:29	:28	:27	:26	:25	:24	:23	:22	ID :21	VIP :20	VIF :19	AC :18	VM :17	RF :16	:15	NT :14	IOPL :13:12	OF :11	DF :10	IF :9	TF :8	SF :7	ZF :6	:5	AF :4	:3	PF :2	:1	CF :0
0	0	0	0	0	0	0	0	0	0	-	-	-	-	-	-	0	-	-	?	-	-	-	S	S	0	?	0	S	1	?

Annotated WinDbg disassembly (x86):

d50a            aad
d50f            aadb    0Fh

Annotated WinDbg disassembly (x64):

d5              ???

Related instructions:

* AAA
* AAM
* AAS