Transcript 8088 assembly language introduction

8088 assembly language introduction
Assistant : 蘇建仲(Su Jain-Zhong)
LAB : ISMP LAB
Tel : 62530-58
E-Mail : [email protected]
Basic Knowledge
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Data Representation
Base Conversion
Binary Arithmetic
80x86 architecture
Addressing mode
80x86 Registers
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IP and Flags
General registers
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Pointers (指標) and Indices (索引)
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AX (Accumulator,累積器)AH/AL
BX (Base), CX (Counter), DX (Data,
aDdress)BH/BL,CH/CL,DH/DL
SP (Stack P.), BP (Base P.)
SI (Source I.), DI (Destination I.)
Segment registers (節段暫存器)

CS (Code程式段), SS (Stack堆疊段), DS (Data資料
段), ES (Extra額外段)
Program example
StSeg
SEGMENT STACK
DW
64 dup (?)
StSeg
ENDS
;------------------------------------------------------------------DtSeg
SEGMENT
Data1
DB
52H
Data2
DB
29H
Sum
DB
?
DtSeg
ENDS
;------------------------------------------------------------------CdSeg
SEGMENT
Main
PROC
FAR
ASSUME CS:CdSeg,DS:DtSeg,SS:StSeg
push
DS
; Program Initialization
mov
AX,0
; (A).Save DS:0 to Stack
push
AX
mov
AX,DtSeg
; (B).Point DS to DtSeg
mov
DS,AX
mov
AL,Data1
; Program Body
add
AL,Data2
mov
Sum,AL
ret
Main
ENDP
CdSeg
ENDS
END
Main
Program structure
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Segmentation
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Procedure definition
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程序名 PROC FAR/NEAR
……………
程序名 ENDP
Segment Register setting
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段名 SEGMENT 參數
……………
段名 SEGMENT
ASSUME CS:CODE,DS:DATA,SS:STACK
Program Entry
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END 程序名
Program Structure(cont)
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Program Initialization
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Store Return-to DOS Address
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Point DS to data segment
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PUSH DS
MOV AX,0
PUSH AX
MOV AX,資料段
MOV DS,AX
Program body
Instruction
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Instruction Format
[label:]
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label
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[operation] [operands] [; comment]
length  247
1st character: English _ ? $@
operation: Mnemonics
operands: (0/1) 2 operands for 80x86
Types of Operations
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Pseudo-Instruction: No Opcode
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i.e. Assembler Directive
Machine code: 1-1 to Opcode
Pseudo Instruction
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Program structure
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SEGMENT ENDS
PROC
ENDP
ASSUME
END
Data structure
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DB - 1B
DW – 2B
DD - 4B
DQ – 8B
DT – 10B
EQU
DUP(duplication)
Pseudo Instruction(cont)
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MACRO
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
名稱 MACRO 參數
………….
ENDM
Conditional assembling
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IF condition
…………
ELSE
…………
ENDIF
General Instructions
MOV destination, source

Destination  source
S
,S
AX
DS
,
O
V
V
M
M
O
general registers
(AX,BX,CX,DX,
SP,BP,SI,DI)
MOV VAR,AX
MOV AX,VAR
AX
,0 MO
10 V
00
11
1B
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MOV CS,any
(x)
AR
,V S
DS R,D
OV A
M VV
MO
AX
segment registers
(CS,SS,DS,ES)
immediate values
MOV V1,V2
(x)
memory variables
VA M
R, OV
01
12
3H
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XCHG destination,source
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Destination  source (Error:XCHG SEG,SEG or MEN,MEN)
Address Loading
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LEA (Effective Address)
LEA
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BX, VAR1[SI]
;  BX=0130
SI, VAR1
;  DS=31AD
LDS
LDS
;  SI=012E

LES
LES
SI, VAR1
;  ES=31AD
;  SI=012E
Stack
CPU
Memory
code
segment
SP <- SP-2
[SP] <- VAR
PUSH VAR
data bus
SP
0100
POP VAR
[SP] <- VAR
SP <- SP+2
0100
0101
0102
VAR
...
...
E2
3A
...
SP-2
SP
SP+2
data
stack
segment segment
D3
84
Push/Pop
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PUSH
PUSH VAR
;  SP=00FE
;  [SP]=[00FE:0100]=84D3
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POP
POP VAR
;  [VAR]=3AE2
;  SP=0102
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PUSHA
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=PUSH AX,BX,CX,DX,SP,BP,SI,DI
POPA
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=POP DI,SI,BP,SP,DX,CX,BX,AX
Flags
8
7
6
NT
IO PC OF DF
IF
TF
SF
ZF
AF
PF
CF
(保護模式權限 )
Interrupt (中斷 )
Trap (單步追蹤 )
Sign (負號 )
Zero (零 )
Carry (進借位 )
NZ/ZR (0/1)
Auxiliary carry
NA/AC (0/1)
(輔助進位 )
Parity (同位 )
PL/NG (0/1)
EV/OD (0/1)
NC/CY (0/1)
Nesting task
(保護模式工作 )
Privilege
UP/DN (0/1)
9
Direction (方向 )
A
0
1
2
3
4
5
B
C
NV/OV (0/1)
D
Overflow (溢位 )
E
F
MOVs of Flags
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PUSHF: Flags (push) Stack
POPF: Flags  (pop) Stack
LAHF: AH (load) Flags
SAHF: AH (save) Flags
Unconditional Jump
JMP
Label
JMP
JMP
SHORT Label
FAR Label
; near jump
(the same segment, push IP)
; short jump (128 bytes)
; far jump
(in different segments, push CS:IP)
JMP L1
JMP L2
L1: ....
L2: ....
Conditional Jump
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Comparison Operators
CMP
J
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AX, BX
Label
}
IF (AXBX) GOTO Label
Unsigned Number
 A (Above), B (Below), E (Equal to)
Signed Number
 G (Greater than), L (Less than), E
Flag Testing
overflow
=1
=0
OF
JO
JNO
sign
SF
JS
JNS
zero
parity
carry
ZF
PF
CF
JZ,JE
JP,JPE
JC
JNZ,JNE JNP,JPO JNC
Unconditional Loop
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Unconditional Loop
L1:
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MOV
…
…
LOOP
CX, Count
L1
Conditional Jump: JCXZ (Jump if CX = Zero)
L1:
L2:
MOV
JCXZ
…
…
LOOP
…
CX, Count
L2
L1
Conditional Loop
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LOOPE/LOOPZ
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find the first “non-blank” element
jump out of loop when
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finished: CX = 0
found: ZF = 1
MOV
CX, 10
L1:
CMP
AL, BL
LOOPE (LOOPZ) L1
General Arithmetic Operations
Unsigned number
Singed number
Operations
8-bit
16-bit
8-bit
16-bit
Addition
ADD AL,BL
ALAL+BL
8
8 8
ADD AX,BX
AXAX+BX
16 16 16
ADD AL,BL
ALAL+BL
8
8 8
ADD AX,BX
AXAX+BX
16 16 16
Subtraction
SUB AL,BL
ALAL-BL
8
8 8
SUB AX,BX
AXAX-BX
16 16 16
SUB AL,BL
ALAL-BL
8
8 8
SUB AX,BX
AXAX-BX
16 16 16
Multiplication
MUL V8
AXAL*V8
16 8
8
MUL V16
DX:AXAX*V16
32 16 16
IMUL V8
AXAL*V8
16 8
8
IMUL V16
DX:AXAX*V16
32 16 16
Division
Sign
Extension
DIV V8
DIV V16
IDIV V8
IDIV V16
AL…AHAX*V8 AX…DX(DX:AX)*V16 AL…AHAX*V8 AX…DX(DX:AX)*V16
8…8 16
8
16…16 32
16
8…8 16
8
16…16 32
16
MOV AH,0
MOV DX,0
CBW (Convert
Byte to Word)
AHAL(7)
CWD (Convert Word to
Double word)
DXAX(15)
Simple Arithmetic
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increment
INC VAR
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decrement
DEC VAR

; VAR  VAR + 1
; VAR  VAR - 1
negation (2’s complement)
NEG VAR
; VAR  - VAR
Overflow
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Addition/Subtraction
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Overflow Flags [ref. Unit 1-11]
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Unsigned number: CF = carry of MSB
Signed number:
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OF = (carry of MSBcarry of 2nd MSB)
Instructions: the same
Multiplication: never overflow
Dividend
Division: Divisor  Quotient ... Remainder
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overflow when
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divisor = 0 (INT 03H)
divisor is too small (INT 04H)
CMP
JAE
DIV
AH,Divisor8
Overflow
Divisor8
Multi-Word Arithmetic Operations
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ADC destination, source
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destination  destination +source +CF
SBB destination, source
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destination  destination - source -CF
Var1
DD
Var2
DD
Result DD
MOV
ADD (SUB)
MOV
MOV
ADC (SBB)
MOV
7ADBDDAAH
3678CC00H
?
AX,WORD PTR [Var1]
AX,WORD PTR [Var2]
WORD PTR[Result],AX
AX,WORD PTR [Var1+2]
AX,WORD PTR [Var2+2]
WORD PTR[Result+2],AX
CF
+)
7ADB
DDAA
3678
CC00
????
????
Bit-wise Operations
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Bit-wise Operations
AND AL,BL
OR AL,BL
NOT AL
XOR AL,BL
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0101 0110
0011 1100
0001 0100
0111 1110
1010 1001
0110 1010
=
=
=
=
=
=
AL
BL
AL
AL
AL
AL
Shifting and Rotation
Shifting Count
Logical
Shifting Shifting
SHL
ROL
ROR
CF
CF
RCL
Arithmetic
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MOV CL, 4
SHL AL, CL
Right
Rotation
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Left
Rotation
through
CF
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Count = 1: SHL AL,1
Count > 1
Shifting
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Rotation
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CF
SHR
0
0
CF
SAL=SHL
CF
CF
SAR
0
S
CF
RCR
CF
Flags and Testing
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Flag Testing
Carry CF
Set (=1)
Clear (=0)
Complement
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Direction DF Interrupt IF
(used in multiplebyte arithmetic)
(used in string
instructions)
(used in interrupt
routine)
STC
CLC
CMC
STD
CLD
STI
CLI
Comparison and Testing


destination is not stored
used with J€
CMP destination, source
: destination – source (SUB)
TEST destination, source
: destination AND source (AND)
Data Transformation
ASCII (American
Standard Code for
Information
Interchange)
'5'
'7'
00110101
00110111
OR AX, 3030H
or XOR AX, 3030H
Unpacked decimal
00000101
0111 DAA,DAS
?
?
SHL AX, 4
SHR AL, 4
Packed Decimal, BCD
0101
(Binary Coded Decimal,
二進制編碼十進位 )
AND AX, 0F0FH
or XOR AX, 3030H
AAA, AAS,
00000111
AAM, AAD
SHL AL, 4
SHR AX,4
AAD
Binary
00111001
AAM
ADD, SUB,
MUL, DIV
BCD Arithmetic
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Addition: Add-6 adjustment
+)
57
39
90
+6)
96
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0101 0111
0011 1001
1001 0000
0110
1001 0110
ADD AL,BL
DAA
=AL
Subtraction: Subtract-6 adjustment
57 0101 0111
-) 39 0011 1001
1E 0001 1110
0110
-6)
18 0001 1000

=AL
=BL
=AL
=BL
SUB AL,BL
DAS
=AL
No adjustment for MUL/DIV
Arithmetic for Unpacked Decimal

Addition: Add-6 adjustment
57 0000 0101 0000 0111 =AL
+) 39 0000 0011 0000 1001 =BL
ADD AL,BL
8? 0000 1000 0001 0000
(AF=1) 0110
AAA
+6)
96 0000 1001 0000 0110 =AL

Subtraction: Subtract-6 adjustment
57 0000 0101 0000 0111 =AL
-) 39 0000 0011 0000 1001 =BL
SUB AL,BL
1E 0000 0001 1111 1110
(AF=1) 0110
AAS
-6)
96 0000 0001 0000 1000 =AL
Arithmetic for Unpacked Decimal
(cont.)

Multiplication: Divide-10 adjustment
)
4
9
36
(binary)
10)
36
(unpacked)

0000 0100 =AL
0000 1001 =BL
0010 0100
MUL BL
(AF=1) 1010
AAM
0000 0011 0000 0110 =AX
Division: Multiply-10 adjustment
36
(unpacked)
10)
(AF=1) 1010
36
(binary)
)
0000 0011 0000 0110 =AX
4
9
AAD
0010 0100
0000 0100 =BL DIV BL
0000 1001 =AL