Chuong 04 8086 Assembly

8/8/2019 Chuong 04 8086 Assembly

1/16

Ch ng 4

8086 Assembly

Xt o n ch ng trnh sau

Int cong (int a, int b)

{

Return (a + b);

}

Void Main()

{

Int x=3; int y=4;

Printf(Tong: %d, cong(x,y));

}

Trong ch ng trnh c hai phn: ph n khai bo v phn l nh cho

ch ng tr nh. Trong ph n l nh c th cph n g i ch ng tr nh con

Nh v y th c hi n m t ch ng tr nh (d ng .EXE).Ng i ta c n t nh t 3 o n b nh (segment). o ndnh ch a d l i u c khai bo, o n ch a mch ng trnh, o n ngn x p (stack) ph c v g ich ng trnh con. M i o n c kch th c 64K. Khich ng tr nh c th c hi n . M i on b nh ny c tr b i thanh ghi o n:

Thanh ghi o n m CS: tr n o n b nh ch a mch ng trnh

Thanh ghi o n d li u DS: tr n o n b nh khaibo ch ng trnh.

Thanh ghi o n ngn x p SS: tr n o n b nh dnhcho stack.

Ngoi ra trong nhi u tr ng h p, ng i ta s d ng thmm t on d li u ph dng trong tr ng h p cc d li uc n khai bo v t qu kch th c cho php c a m t

o n. Khi thanh ghi d l i u ES s tr n

Ngn ng my (Machine language)

M i ki n trc my tnh c m t ngn ngmy ring. Ngn ng my l ngn ngduy nh t my c th hi u c.

Ngn ng my l cc m l nh, v vi cghp n i cc m l nh v i d li u, a ch

Vi c l p trnh b ng ngn ng my r t khkhn v ph c t p

Dng ngn ng c p cao h n

H p ng (Assembly language)

d ghi nh ng i ta dng m gi(mnemonic), tn g i (label)

H p ng l ngn ng m cc m l nh lm gi , d li u ho c a ch l cc label.Chng ta ghp n i l i theo m t c u trc

V d

mov al, 061h

Trnh bin dch h p ng(assembler)

Ch ng trnh vi t b ng h p ng ctrnh bin dch (assembler) dch sang m

my my tnh c th hi u. V i m t ki n trc my tnh c th c nhi u

trnh bin dch c a nhi u nh cung c p,ch y trn nhi u h i u hnh khc nhau

V d v i cng ki n trc x86 nh ng cnhi u trnh bin dch: A86, GAS, TASM,MASM, NASM


2/16

V d ch ng tr nh h p ng

Hello.asm

.MODEL SMALL .STACK 100H

.DATA MyStr DB "HELLO ASM !$" .CODE MOV AX, @DATA MOV DS, AX LEA DX, MyStr MOV AH,9 INT 21H MOV AH, 4CH INT 21H END

Cch th c ch ng trnh lm vi c

Ngu n 1 Ngu n 2 Ngu n 3Ch ng tr nhngu n .ASM

Trnh bin dch

Ch ng tr nh

lin k t

it ng 1

it ng 2

it ng 3

Ch ngtrnh th c thi

.COM

Ch ngtrnh th c thi

.EXE

Th

vi n

MASM.exe

M i t ng ( .OBJ)

B ng li t k (.LST)

Tham kh o cho (.CRF)

LINK.EXE

M th c thi (.COM)

M th c thi (.EXE)

Bn ( .MAP)

M ASCII000 001 010 011 100 101 110 111

0000 NU LL D LE 0 @ P ` p0001 SOH DC1 ! 1 A Q a q0010 STX DC2 " 2 B R b r0011 ETX DC3 # 3 C S c s0100 EDT DC4 $ 4 D T d t0101 ENQ NAK % 5 E U e u0110 ACK SYN & 6 F V f v0111 BEL ETB ' 7 G W g w1000 BS CAN ( 8 H X h x1001 HT EM ) 9 I Y i y1010 LF SUB * : J Z j z1011 VT ESC + ; K [ k {1100 FF FS , < L \ l |1101 CR G S - = M ] m }1110 SO RS . > N ^ n ~

1111 SI US / ? O _ o DEL

000 001 010 011 100 101 110 1110000 NU LL D LE 0 @ P ` p0001 SOH DC1 ! 1 A Q a q0010 STX DC2 " 2 B R b r0011 ETX DC3 # 3 C S c s0100 EDT DC4 $ 4 D T d t0101 ENQ NAK % 5 E U e u0110 ACK SYN & 6 F V f v0111 BEL ETB ' 7 G W g w1000 BS CAN ( 8 H X h x1001 HT EM ) 9 I Y i y1010 LF SUB * : J Z j z1011 VT ESC + ; K [ k {1100 FF FS , < L \ l |1101 CR G S - = M ] m }1110 SO RS . > N ^ n ~1111 SI US / ? O _ o DEL

Most significant bit

Least significant bit

000 001 010 011 100 101 110 1110000 NU LL D LE 0 @ P ` p0001 SOH DC1 ! 1 A Q a q0010 STX DC2 " 2 B R b r0011 ETX DC3 # 3 C S c s0100 EDT DC4 $ 4 D T d t

0101 ENQ NAK % 5 E U e u0110 ACK SYN & 6 F V f v0111 BEL ETB ' 7 G W g w1000 BS CAN ( 8 H X h x1001 HT EM ) 9 I Y i y1010 LF SUB * : J Z j z1011 VT ESC + ; K [ k {1100 FF FS , < L \ l |1101 CR G S - = M ] m }1110 SO RS . > N ^ n ~1111 SI US / ? O _ o DEL

e.g., a = 1100001 95 Graphic codes

000 001 010 011 100 101 110 1110000 N ULL DLE 0 @ P ` p0001 SOH DC1 ! 1 A Q a q0010 STX DC2 " 2 B R b r0011 ETX DC3 # 3 C S c s0100 EDT DC4 $ 4 D T d t

0101 ENQ NAK % 5 E U e u0110 ACK SYN & 6 F V f v0111 BEL ETB ' 7 G W g w1000 BS CAN ( 8 H X h x1001 HT EM ) 9 I Y i y1010 LF SUB * : J Z j z1011 VT ESC + ; K [ k {1100 FF FS , < L \ l |1101 CR GS - = M ] m }1110 SO RS . > N ^ n ~1111 SI US / ? O _ o DEL
http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/


3/16

33 Control codes


Alphabetic codes

000 001 010 011 100 101 110 1110000 N ULL DLE 0 @ P ` p0001 SOH DC1 ! 1 A Q a q0010 STX DC2 " 2 B R b r0011 ETX DC3 # 3 C S c s0100 EDT DC4 $ 4 D T d t0101 ENQ NAK % 5 E U e u0110 ACK SYN & 6 F V f v0111 BEL ETB ' 7 G W g w1000 BS CAN ( 8 H X h x1001 HT EM ) 9 I Y i y1010 LF SUB * : J Z j z1011 VT ESC + ; K [ k {1100 FF FS , < L \ l |1101 CR GS - = M ] m }1110 SO RS . > N ^ n ~1111 SI US / ? O _ o DEL

Numeric codes


000 001 010 011 100 101 110 1110000 N ULL DLE 0 @ P ` p0001 SOH DC1 ! 1 A Q a q0010 STX DC2 " 2 B R b r0011 ETX DC3 # 3 C S c s0100 EDT DC4 $ 4 D T d t0101 ENQ NAK % 5 E U e u0110 ACK SYN & 6 F V f v0111 BEL ETB ' 7 G W g w1000 BS CAN ( 8 H X h x1001 HT EM ) 9 I Y i y1010 LF SUB * : J Z j z1011 VT ESC + ; K [ k {1100 FF FS , < L \ l |1101 CR GS - = M ] m }1110 SO RS . > N ^ n ~1111 SI US / ? O _ o DEL

Punctuation, etc.

Ki n trc t p l nh 8086

Pop flags fromstack

POPFPush flags ontostack

PUSHF

Load effectiveaddress

LEATranslateXLAT

Load ES withsegment and

register with offset

LESLoad DS vithsegment andRegister with

offset

LDS

Store AH in flagsSAHFLoad AH withFlags

LAHF

OutputOUTInputIN

exchangeXCHGPopPOP

PushPUSHMoveMOV

InstructionMnemonicInstructionMnemonic

Nhm l nh di chuy n d liu

L nh MOV

Ch c nng: chuy n gi tr t ton h ng ngu n vo tonh ng ch.

C php:MOV ch (Dst), ngu n (Src)

reg1, reg 2Reg, datamem, regReg, memmem, data

Ch :- Data chn m pha ngun- Hai ton h ng Dst, Src khng th ng th i l hai

nh
http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/http://0000NULLDLE0@p/


4/16

L nh PUSH

Ch c nng: chuy n gi tr ton h ng ngu n vonh ngn x p

C php

PUSH Src v d

reg16 push ax

mem16 push x

Segreg push DS

Ch :

- Ton h ng ngu n lun c kch th c 16 bit

- Ton h ng ngu n khng th l data (h ng s )

L nh POP

Ch c nng: l y gi tr nh ngn x p a voton h ng ch

C php:

POP Dst v d

Reg16 POP AX

mem16 POP X

Segreg POP DS

Ch :

- Ton h ng ngu n lun c kch th c 16bit

- Ton h ng ngu n khng th l data (const)

L nh PUSHF

Ch c nng: chuy n gi tr thanh ghi cvo nh ngn x p

C php:

PUSHF

L nh POPF

Ch c nng: l p gi tr nh ngn x p l uvo thanh ghi c

C php:

POPF

L nh XCHG

Ch c nng: hon v gi trgi a ton h ngngu n v ch

C php:

XCHG Dst, Src v d

Reg, Reg XCHG AX, BXReg, Mem XCHG AX, [BX]

Mem, Reg XCHG [BX], AX

L nh IN

Ch c nng: c gi tr t m t c ng vothanh ghi AL ho c AX.

C php:

IN AL, a ch c ng (8bit)

IN AX, a ch c ng (16bit)


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L nh MUL

Ch c nng: Nhn n i dung c a ton h ng AX ho c AL v i n i dungc a ton h ng ngu n. Gi tr c a hai ton h ng l d ng khng d u.K t qu c c t nh sau:+ N u l php nhn hai ton h ng 8 bit th k t qu c t trong

AX+ N u l php nhn hai ton h ng 16 bit th k t qu c t trongDX:AX

C p hp:

MUL Src V dReg MUL CL

Mem MUL xCh :

- Ton hng ngu n khng th lh ng s- K t qu cth tc ng n cc c : OF, ZF, CF

L nh DIV

Chia gi tr c a thanh ghi AX ho c DX:AX cho n i dung c a tonh ng ngu n. Gi tr c a hai ton h ng l d ng khng d u. K t qus c c t nh sau :+ N u s bchia l ton h ng 16 b it th phn th ng s c t

trong AL, v ph n d t trong AH+ Nu b chia l ton h ng 32 bit th ph n th ng s c t trongAX, v ph n d u t trong DX

C p hp:

DIV Src V dReg DIV CL

Mem DIV [BX]Ch :

- Ton hng ngu n khng th lh ng s- K t qu c th tc ng n c : OF, CF

L nh CMP

Ch c nng: So snh gi tr c a ton h ng ch v ton h ng ngu n.N i dung c a hai ton h ng khng thay i sau l nh ny. L nh nyth c hi n b ng cch l y ton h ng ch tr i ton h ng ngu n. K tqu ph n nh ln thanh ghi c v khng c l u l i

C phpCMP Dst, Src V d

reg1, reg2 CMP AX, BXReg, Data CMP AH, 9FhMem, Reg CMP [BX], AXReg, Mem CMP CX, [1234h]Mem, Data CMP [BX], FFh

Ch :- Hai ton h ng khng th ng th i l h ng s ho c nh

- K t qu cth tc ng n c : OF, SF, ZF, AF, PF, CF

Nhm l nh tnh ton logic

Exclusive ORXOR

Rotate left with CarryRCLRotate rightROR

Bitwise ANDANDRotate with CarryRCR

Bitwise ORORLogical compareTEST

Rotate leftROLArithmethic shift rightSAR

Logical shift rightSHRArithmethic shift leftSAL

Logical shift leftSHLInvertNOT

InstructionMnemonicInstructionMnemonic

L nh NOT

Ch c nng: o gi tr t ng bit m t c aton h ng ch

C php:NOT Dst V d

Reg NOT CL

Mem NOT [BX]

Ch :

- Ton h ng ch khng th l h ng s

L nh AND

Ch c nng: th c hi n php AND logic gi a hai ton h ng, kt qu tvo ton h ng ch

C p hp:AND Dst, Src V d

Reg1, Reg2 AND AX, BXReg, Data AND AH, 9Fh

Mem, Reg AND [BX], AXReg, Mem AND CX, [1234h]

Mem, Data AND BX, FFhCh :

- Ton h ng ngu n v ch khng th ng th i l nh ho c h ng s- K t qu cth tc ng n cc c : SF, ZF, PF


7/16

L nh OR

Ch c nng: Th c hi n php OR logic gi a hai tonh ng, k t qu t trong ton h ng ch

C php:

OR Dst, Src V dReg1, Reg2 OR AX, BXReg, Data OR AX, 12hMem, Reg OR [BX], ALReg, Mem OR CL, [1234h]Mem, data OR [BX], FFh

Ch :- Hai ton h ng khng ng th i l h ng s ho c nh- K t qu c th tc ng n cc c : SF, ZF, PF

L nh XOR

Ch c nng: th c hi n php exclusive OR gi a hai ton h ng, ktqu t ton hng ch

C p hp:XOR Dst, Src V d

Reg1, Reg2Reg1, DataMem, regReg, MemMem, Data

Ch :- Hai ton hng khng th ng th i l hng s ho c nh- K t qu cth tc ng n cc c : SF, ZF, PF

L nh TEST

Ch c nng: so snh n i dung hai ton h ng b ng cch th c hi nl nh AND gi a hai ton h ng m khng l u l i k t qu . Kt qu tc ng n thanh ghi c

C p hp:TEST Dst, Src

Reg1, Reg2Reg, data

Mem, regReg, Mem

Mem, dataCh - Hai ton h ng khng ng th i l hng s ho c nh- K t qu cth tc ng n cc c : SF, ZF, PF

L nh SHL/SAL

Ch c nng: dch tri cc bit c a ton h ng ch iCOUNT l n. Trong CL = COUNT

C php:SHL/SAL Dst, COUNT V d

Reg SHL AL, CLMem SHL [BX], CL

Ch :- Hai ton h ng khng ng th i l h ng s ho c nh- Khi Count =1 th c th t 1 tr c ti p vo ton h ng v

d SHL/SAL Dst, 1- K t qu c th tc ng n cc c : OF, SF, ZF, PF, CF

L nh SHR

Ch c nng: dch ph i cc bit c a ton h ng ch iCOUNT l n, trong CL = COUNT

C php:

SHR Dst, COUNT V dReg SHR AL, CLMem SHR [BX], CL


d SHL/SAL Dst, 1- K t qu c th tc ng n cc c : OF, SF, ZF, PF, CF

L nh ROR

Ch c nng: quay vng ph i cc bit c a ton h ng chi COUNT l n. Trong CL = COUNT. Trong m i l nquay, gi tr bit th p nh t v a chuy n vo thanh ghi cCF, ng th i chuy n vo bit cao nh t.

C php:ROR Dst, COUNTV d

Reg ROR AL, CLMem ROR [BX], CL


d ROR Dst, 1- K t qu c th tc ng n cc c : OF, CF


8/16

L nh ROL

Ch c nng: quay vng tri cc bit c a ton h ng ch iCOUNT l n. Trong CL = COUNT. Trong m i l nquay, gi trbit l n nh t v a chuy n vo thanh ghi cCF, ng th i chuy n vo bit th p nh t.

C php:ROL Dst, COUNTV d

Reg ROL AL, CLMem ROL [BX], CL


d ROL Dst, 1- K t qu c th tc ng n cc c : OF, CF

Nhm l nh thao tc STRING

Load StringLODS

Store StringSTOS

Compare stringCMPS

Move a stringMOVS

RepeatREP

InstructionMnemonic

L nh MOVSB (MOVSW)

Ch c nng: chuy n m t xu k t theo t ngbyte (ho c theo t ng t ) t vng nh ngu nsang vng nh ch. Trong , DS:SI tr nxu k t ngu n v ES: DI tr n xu k tch. Sau m i l n chuy n 1 byte ho c 1 t thgi tr c a SI v DI t ng tng ln 1 (ho c 2)n u c h ng DF=0, ho c gi m i 1 (ho c 2)n u c h ng DF=1.

C php: MOVSB ho c MOVSW

L nh CMPSB (CMPSW)

Ch c nng: so snh hai xu k t theo t ngbyte (ho c t ng t ) n m hai vng nh . Trong, DS:SI v ES: DI tr n hai xu k t . Saum i l n so snh t ng byte (ho c word) th gi trc a SI v DI t ng tng ln 1 (ho c 2) n u cDF=0 v gi m i 1 (ho c 2) n u c DF=1.

C php:CMPSB ho c CMPSW K t qu c th tc ng n cc c : OF, SF, ZF,

AF, PF, CF

L nh LODSB (LODSW)

Ch c nng: chuy n n i dung theo t ngbyte (ho c t ng t ) c a vng nh tr b i

DS:SI vo thanh ghi AL (ho c AX). Saum i l n chuy n th gi tr c a SI t ngtng ln 1 (ho c 2) n u DF = 0 v gi m i1 (ho c 2) n u DF=1.

C php: LODSB ho c LODSW

L nh STOSB (STOSW)

Ch c nng: chuy n n i dung theo t ngbyte (ho c t ng t ) c a thanh ghi AL

(ho c AX) t i vng nh tr b i ES: DI.Sau m i l n chuy n t ng byte (t ng t ) thgi tr c a DI t ng tng ln 1 (ho c 2)n u c DF=0 v gi m i 1 (ho c 2) n u cDF = 1

C php: STOSB ho c STOSW


9/16

Nhm l nh chuy n i u khi n

LOOPNZ

JO

JNB

JNE

JBE

JZ

LOOPE

JNP

JG

JS

JC

JE

JNOJAJNBEJNC

LOOPENELOOPZLOOP (tng gi m

CX 1 n v)

JNS

RETINTJCXZ

JAEJNLEJGEJNL

JNZJOJPEJP

JNAJNAEJBJNGE

JLJMPRETCALL

Lnh nhy b t u b ng ch J, sau l iu kin. Vd : JGE(Jump if Greater than or Equal)

L nh CALL

Ch c nng: g i ch ng trnh con C php:

CALL a chNhnTn ch ng trnh conRegMem

L nh RET

Ch c nng: quay tr v ch ng tr nh g i ch ng trnh con

C php:RET

L nh JMP

Ch c nng: l nh nh y khng i u ki n C php:

JMP a chNhnTn ch ng trnh conRegMem

Ch : b c nh y c a l nh ny n m trong m to n 64KB

Cc l nh nh y c iu ki n

Cc b c nh y c a l nh nh y c i u ki n khng v t qu 128 byte

Cc l nh l p Ch c nng: th c hi n vng l p cho n khi i u

ki n th a mn. C php:

- LOOP nhn (l p kh i l nh t nhn n LOOPcho n khi CX=0. Sau m i l n gi tr CX gi mi 1.- LOOPZ/LOOPE nhn (l p kh i l nh t nhn n LOOP ho c LOOPE cho n khi CX = 0 vc ZF = 1. Sau m i l n th c hi n gi tr c a CXgi m i 1.- LOOPNZ/LOOPNE nhn (l p kh i l nh t nhn n LOOPNZ/LOOPNE cho n khi CX0 vc ZF=0. Su m i l n th c hi n CX gi m i 1.


10/16

Cc l nh g i ng t m m

L nh INT- ch c nng: Th c hi n ng t m m

- C php: INT s hi u ng t (hexa)- Cc c b tc ng: IF, TFL nh IRET

- Ch c nng: tr v ch ng trnh chnh sau khith c hi n ch ng tr nh con g i ng t- C php: IRET- Cc c b tc ng: OF, SF, ZF, AF, PF, CF

Cc l nh i u khi n khc

L nh CLC- ch c nng: xa gitrc CF v 0 (CF=0)- c php: CLC- C b tc ng CF

Lnh CMC- Ch c nng: o gi t r h in th i c a c CF- c php: CMC- C b tc ng: CF

Lnh STC

- Ch c nng: t c CF = 1- C php: STC- C b tc ng: CF

Lnh CLD- Chc nng: xa gitrc DF (DF=0)- C php: CLD- C b tc ng: DF

Lnh STD- Ch c nng: t c DF =1- C php: STD- C b tc ng: DF

Lnh CLI- Ch c nng: xa cc c IF (IF=0). C m cc ngt c ng ho t ng, tr cc ng t khng che- C php: CLI- C b tc ng: IF

L nh STI- Ch c nng: t IF=1. Cho php cc ng t c ngho t ng- C php: STI- C nh h ng: IF

L nh HTL- Ch c nng: d ng my- C php: HTL

L nh NOP- Ch c nng: khng lm g- C php: NOPCh : l nh NOP r t c ngha khi CPU th chi n cc chu k i c xen vo m t s chu k

l nh trong qu trnh th c hi n l nh

CCH TH C L P TRNH

M t s ch c nng c a ng t 21h

Ph n ny trnh by cc hm thng d ng c ang t 21h. l cc hm thao tc vo/ra i v ik t , chu i k t , file, th m c, k t thc ch ng

trnh v tr quy n i u khi n cho DOS Hm 01: c 1 k t (c hi n) t bn phmInput: AH=01Output: AL = m ASCII c a k t

AL = 0 n u g vo phm ch c nng Hm 02: hi n m t k t ln mn hnh

Input: AH=02Output: DL=m ASCII k t c n hi n th

Hm 08: c m t k t (khng hi n) tbn phmInput: AH =08Output: AL=m ASCII k t

AL =0 n u g vo phm ch cnng

Hm 09: hi n xu k t k t thc b i $ lnmn hnh

Input: AH=09DX=a ch offset c a xu k t


11/16

Hm 0Ah:Input: AH=0Ah

DX = a choffset c a vng m ch a xu k tOutput: DX = a ch offset c a xu k t

Hm 39h: t o th mcInput: AH = 39h

DX = a ch offset c a tn th m cOutput: - N u thnh cng th m c c t o ra

- N u khng thnh cng CF=1 v AX=m l i Hm 3Ah: xa th mc

Input: AH =3AhDX = a ch offset c a tn th m c

Output:- N u thnh cng, th m c c xa- N u khng thnh cng, CF=1 v AX=m l i

Hm 3Ch: t o fileInput: AH=3Ch

DX = a ch offset c a tn fileCX = thu c tnh file

Output:- N u thnh cng, file c t o ra CF=0 v AX = th

file (file handle)- N u khng thnh cng, CF=1 v AX = m l i

Thu c tnh file c nh ngha nh sau:00h: file bnh th ng01h: file ch c02h: file n04h: file h th ng08h: thu c tnh cho nhn a10h: thu c tnh cho th m c con

Hm 3Dh: m fileInput: AH=3Dh

AL = modeOutput:

- N u thnh cng, file c m , CF=0v AX=th file (file handle)

- N u khng thnh cng, CF=1 vAX=m l i

Hm 3Eh Hm 3Fh Hm 40h Hm 41h Hm 4Ch: k t thc ch ng trnh

Input: AH = 4ChOutput: k t thc ch ng trnh, tr quy ni u khi n cho h i u hnh

Cch t tn

Quy t c t tn bi n v nhn: b t u b ng m tk t khc s , cc k t dng t tn: a-z, A-Z, 0-9, ?, @, _, $

Ch ng trnh khng phn bi t ch hoa, chth ng. Bi u di n cc gi tr

- S nh phn: xxxxxxB (010101B)- S bt phn: xxQ ho c xxO (123Q)- S th p phn: xxx (123)- S th p l c phn (s Hex): xxxxH, b t ub ng s (1230H, 0124H)

CCH KHAI BO BI N

Cc bi n c th c khai bo v i 3 ki ud li u khc nhau: ki u byte, ki u word,ki u double word

+ Bi n ki u byte:D ng khai bo: Tn bi n DB ?V d : X DB ?;khng c

gi tr kh i uY DB 4;gi tr kh i

u l 4


12/16

Bi n ki u wordD ng khai bo: Tn bi n DW ?V d : X DW ?;khng c gi

tr kh i uY DW 4;gi tr kh i

u l 4 Bi n ki u double wordD ng khai bo: Tn bi n DD ?V d : X DD ?;khng c gi

tr kh i uY DD 4; gi tr kh i

u l 4

Khai bo bi n ki u m ngM ng l m t dy lin ti p cc ph n t c cng byte ho ctv d : A1 DB 1,2,3,4,5

L khai bo m t bi n m ng c tn A1, g m 5 byte trong bnh . N i dung nh [A1] c gi tr l 1, [A1+1] l 2...

N u khai bo m t m ng khng c n gi tr ban u ta khaibo nh sau:

A2 DB 100 DUP (?)Khai bo m ng c 100 ph n t v cc ph n t l ki u ByteKhai bo nh sau:

A3 DB 100 DUP (0)Khai bo m ng c 100 ph n t ki u byte v i gi tr l 0

Khai bo bi n ki u xu k tXu k t l m t m ng m m i ph n t lm t k t hay m ASCII c a k t . Xu kt k t thc b i k t $ (c m ASCII l24h)

V d :xu1 DB cho cc b n$

Khai bo h ngH ng c th l ki u s ho c ki u k t

C php nh sau:Tn h ng EQU gi tr c a h ng

V d :Chao EQU Cho b nCR EQU 11h

Ton t DUP

Ch xu t hi n sau DB ho c DW V i DUP ta c th l p l i 1 hay nhi u gi

tr cho vng nh R t c ch khi lm vi c v i m ng ho c

chu i V d :

Matrix dw 3 dup (4 dup(0)); matr n 3x4

Ton t ?

Mu n khai bo m t bi n hay m t m ng mkhng c n kh i t o gi tr ta dng ton t?

V d :MEM DB ? ; khai bo 1 byte tr ng trong bnhBMEM DB 50 DUP(?) ; khai bo 50 bytetr ng trong b nh


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KHUNG CH NG TRNH

1. Ch th .MODEL: kch th c ch ng tr nh vd l i u- Tiny: code + data = 64KB (khng c bin no kch th c> 64KB)

- Huge: code >= 64KB, data >= 64KB (m t bi n cth c kch th c> 64KB)

2. Ch th .STACK khai bo kch th c vng stack cho ch ng trnhv d :.stack 100H khai bo stack c 256 byte

3. Chth .DATA khai bo vng d li u- Dng cc chth DB, DW, DD khai bo cc bi n kiu d li u byte, word,double word ho c array

+ C php bi n Byte (DB):Tn DB Gi tr kh i uV d : A DB 1

+ C php bi n Word (DW):Tn DW Gi tr kh i u

V d : A DW 2+ C php bin Double Word (DD)

Tn DD Gi tr kh i uV d : A DD 4

+ Bi n m ng 1 chi u:Tn DB Gi trV d : M1 DB 1,2,3,4,5

+ Bi n mng nhi u chiuTn DB Gi tr

DB Gi tr

+ K tTn DB string

V d : string1 DB 123+ Khai bo h ng (EQU)

V d : a EQU 0, value EQU 100+ LABEL dng nh d u a ch ho c thay i ki u d li u

ca bi nV d : day LABEL Byte

4. Ch th .CODE khai bo vng ch ng trnh

.CODEMain PROC ; ch ng trnh chnh

MOV AX, @DATAMOV DS, AXCALL CTC ; g i ch ng trnh con---------MOV AH, 4CH ; K t thc v DOSINT 21H

Main ENDP ;k t thc ch ng trnh chnhCTC PROC ; ch ng trnh con

CTC ENDP ; K t thc ch ng trnh con

Khung ch ng trnh d ng .EXE

Khung ch ng trnh khi dch thnh filech y d ng .EXE

Ta dng Start v End start nh d ui m b t u v k t thc o n m l nhdng cho ch ng trnh (c th dng tnkhc Start)

.model small

.stack 100h

.Data;cc khai bo h ng, bi n y

.Code

Start:Mov AX, @DataMov DS, AX;cc l nh c a ch ng trnh chnh vi t yMov AH, 4Chint 21h

End Start;cc ch ng tr nh con n u c s c vi t y
http://data/http://data/http://data/


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o n l nhMov AX, @DataMov DS, AXlm nhi m v cho con tr DS tr t i vng d l i u khaibo (Data). @Data l a chc a on b nh cp pht

cho ch ng trnh trong qu trnh ch y. M DS khng thlm vi c tr c ti p v i h ng s (khng th chuy n tr cti p h ng s vo thanh ghi o n) nn thanh ghi AX lbi n trung gian a @Data vo DS.

Hai o n l nh cu iMov AH, 4ChInt 21h

Lm nhi m v k t thc ch ng trnh EXE.Tr quy n i u khi n l i cho ch ng trnhDOS. Nh c l i, khng gi ng cc h i uhnh khc (windows l h i u hnh anhi m), h i u hnh DOS l h i u hnh n nhi m. Ngha l, t i m t th i i m chc m t ch ng trnh chi m quy n i ukhi n v ti nguyn c a h th ng

V d Ch ng trnh Hello World n gin. Ch ng trnh th c hi n vic in ra mn hnh l i

cho Hello World;ch ng trnh in ra mn hnh Hello World.Model Small.Stack 100h.Data

Msg db Hello World,$.CodeStart:

Mov AX, @DataMov DS, AX ;cho DS tr n o n dataMov AH, 09h;hm 09 in ra 1 xu k tMov DX, offset Msg; DX ch a a choffset c a xuInt 21hMov AH, 4Ch ; tr quy n iu khi n cho DOSInt 21h

End Start

KHUNG CH NG TRNH D NG COM

Ch ng tr nh .COM n gi n v ng n g nh n .EXE. T t c cc o n ngn x p, dli u, o n m c g p vo cng m to n l o n m. Ngha l ch ng trnh.COM c gi g n trong m t o n. V icc ng d ng nh m d li u v m l nhkhng v t qu 64KB, ta c th ghp luncc o n ngn x p, d li u v m l nhvo cng v i o n m t o ra file d ng

.COM

C u trc nh sau

.Model Tiny

.CodeOrg 100hJMP Start; cc khai bo h ng, bi n y

Start:; cc l nh c a ch ng trnh chnh c vi t y

Int 20h; cc ch ng trnh con n u c c vi t y

End Start

Khai bo m hnh kch th c s d ng bnh lun l Tiny. Ngoi ra trong khung nykhng c khai bo ngn x p v d li u.L nh u tin trong o n m l gi l nh

ORG 100h, dng gn a ch b t ucho ch ng trnh t i 100h trong o n m.K ti p ng i ta s d ng l nh JMP nh y qua b nh dnh cho vi c khai bo
http://data/http://data/http://data/http://data/http://data/http://data/http://data/


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V d.Model Tiny.Code

Org 100hJMP Start

Msg db Hello World , $Start:

Mov AH, 09h;hm 09 in ra xu k tMov DX, offset MsgInt 21h ; th c hi n ch c nng in xuInt 20h ; k t thc ch ng trnh v DOS

End start

C u trc l p trnh c b n th c hi nb ng assembly

If i u ki n then cng vi c (dng l nh sosnh v l nh nh y)

V d : Gn cho BX gi tr tuy t i c a AX;if AX < 0CPM AX, 0JNL ENDIFNEG AX

ENDIF: MOV BX, AX

IF i u ki n then cng vi c 1 else cng vi c2

V d : IF AX < BX then CX = 0 else CX = 1;if AX < BXCPM AX, BXJL THENMOV CX, 1JMP END IFTHEN: MOV CX, 0END IF:

C u trc l a ch n CASECase bi u th c

Gi tr1: cng vi c 1Gi tr2: cng vi c 2 ..Gi trN: cng vic N

V d :N u AX < 0 th CX=1N u AX = 0 th CX=0N u AX > 1 th CX=1

CMP AX, 0JL Am ; AX 0

AM: MOV CX, 1JMP ENDCASE

Bang: MOV CX, 0JMP ENDCASE

DUONG: MOV CX, 1ENDCASE:

C u trc l p FOR - DOFor s l n l p Do cng vi c

kh i t o b m

cng vi c

gi m b m i 1

b m=0?S

Hi n th dng k t $ ln mn hnh

Mov CX, 80 ; s l n l p

Mov AH, 2 ; hm hi n th

Mov DL, $ ; k t hi n th

HIEN: INT 21H ; hi n th

LOOP: HIEN

ENDFOR:

C u trc vng l p While - DoWhile i u ki n Do cng vi c

cng vi c

i u ki n

S

Vd : m s k t c t bn phm khigp k t CR th thi

XOR CX, CX ; CX=0

MOV AH, 1 ;hm c k t t bn phm

TIEP: INT 21H ; c m t k t vo AL

CPM AL, 13 ; CR?

JE ENDWHILE

INC CX ; tng CX ln 1

JMP TIEP ; ti p t c

ENDWHILE


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C u trc l p REPEAT - UNTILREPEAT cng vi c UNTIL i u ki n

cng vi c

i u ki n

S

Vd : c t bn phm khi g p k tCR th thi?

MOV AH, 1 ; L NH C BN PHM

TIEP: INT 21H ; C K T VO AL

CPM AL, 13 ; SO SNH CR?

JNE TIEP ; CH A, C Ti P

END:

Ch ng trnh con C u trc ch ng trnh con PROC Near/FarCc l nh ch ng trnh con

RET ENDP Gi i thch

Macro Macro bao g m m t tn i di n v m t

kh i l nh. Khi ch ng trnh dch h p ngg p tn ny u trong ch ng trnh thkh i l nh c dch v t kh i m l nhvo v tr m ch ng trnh g i tn Macro

Khai bo MacroTn Macro MACRO cc tham sThn MacroENDM

Vect h th ng

- 8086 dnh 1KB b nh cho cc vect ng t v ngo i l(exception)

- S ng t l m t ton h ng 1 byte (0 255). K t qu caphp nhn s ng t v i 4 s ch t i vector ng t t ng ng (n i dung c a vector ng t l offset v segment c ach ng tr nh x l ng t)

- V d l nh INT 21H, lm 8086 tm n a ch 00084Hl y offset n p vo thanh ghi IP v segment n p vothanh ghi CS

Kh i ng h th ng

- Khi reset 8086, ton b cc thanh ghi s tr v 0, ngo itr thanh ghi CS s c kh i t o l 0FFFFh v l nh.L nh u tin c th c hi n a ch 0FFFh:00000h

- H th ng my tnh 8086 th ng c b nh ROM n m a ch cao ch a code kh i ng khi h th ng reset

- Khi kh i ng, cng vi c u tin th ng l kh i t ob ng vector vng a chth p

Bi t p

Chuong 04 8086 Assembly

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Transcript of Chuong 04 8086 Assembly