Intel 64 and IA-32 Architectures Software Developers Manual Volume 2B, Instruction Set Reference, N-Z

Vol. 2B B-9

INSTRUCTION FORMATS AND ENCODINGS

B.1.5 Other Notes

Table B-12 contains notes on particular encodings. These notes are indicated in the

tables shown in the following sections by superscripts.

B.2 GENERAL-PURPOSE INSTRUCTION FORMATS AND

ENCODINGS FOR NON-64-BIT MODES

Table B-13 shows machine instruction formats and encodings for general purpose

instructions in non-64-bit modes.

Table B-12. Notes on Instruction Encoding

Symbol Note

A A value of 11B in bits 7 and 6 of the ModR/M byte is reserved.

Table B-13. General Purpose Instruction Formats and Encodings

for Non-64-Bit Modes

Instruction and Format Encoding

AAA – ASCII Adjust after Addition 0011 0111

AAD – ASCII Adjust AX before Division 1101 0101 : 0000 1010

AAM – ASCII Adjust AX after Multiply 1101 0100 : 0000 1010

AAS – ASCII Adjust AL after Subtraction 0011 1111

ADC – ADD with Carry

register1 to register2 0001 000w : 11 reg1 reg2

register2 to register1 0001 001w : 11 reg1 reg2

memory to register 0001 001w : mod reg r/m

immediate to register 1000 00sw : 11 010 reg : immediate data

immediate to AL, AX, or EAX 0001 010w : immediate data

immediate to memory 1000 00sw : mod 010 r/m : immediate data

ADD – Add

register1 to register2 0000 000w : 11 reg1 reg2

register2 to register1 0000 001w : 11 reg1 reg2

memory to register 0000 001w : mod reg r/m

immediate to register 1000 00sw : 11 000 reg : immediate data