inter80386

Encoding of 32-bit Address Mode with "mod rIm" byte (no "s-i-b" byte present):

mod rIm

Effective Address

00000

OS: [EAX)

00001

OS: [ECX)

00010

OS:[EOX)

00011

OS:[EBX)

00100

s-i-b is present

00101

OS:d32

00110

OS: [ESI)

00111

OS:[EOI)

01000

OS:[EAX+dS)

01001

OS: [ECX + dS)

01

010

OS:[EOX+dS)

01

011

OS:[EBX+dS)

01

100

s-i-b is present

01

101

SS: [EBP + dS)

01

110

OS: [ESI + dS)

01

111

OS: [EOI + dS)

mod rIm

Effective Address

10000

OS:[EAX+d32)

10001

OS: [ECX + d32)

10010

OS: [EOX + d32)

10011

OS: [EBX + d32)

10100

s-i-b is present

10101

SS: [EBP + d32)

10110

OS: [ESI + d32)

10 111

OS: [EOI + d32)

11 000

register-see below

11001

register-see below

11010

register-see below

11 011

register-see below

11 100

register-see below

11 101

register-see below

11 110

register-see below

11 111

register-see below

Register Specified by reg or rIm during 16-Bit Data Operations:

mod rIm

function of w field

(when w=O)

(when w= 1)

 

11000

AL

AX

11001

CL

CX

11 010

DL

DX

11 011

BL

BX

11100

AH

SP

11 101

CH

BP

11 110

DH

SI

11 111

BH

01

Register Specified by reg or rIm during 32-Bit Data Operations:

mod rIm

function of w field

(whenw=O)

(whenw= 1)

 

11 000

AL

EAX

11001

CL

ECX

11 010

OL

EOX

11 011

BL

EBX

11100

AH

ESP

11 101

CH

EBP

11 110

DH

ESI

11 111

BH

EDI

129

Page 190
Image 190
Intel 80386 manual Os Eax