Lesson 8 Instruction Set and Programming

5/20/2018 Lesson 8 Instruction Set and Programming

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INSTRUCTION SET

AND

PROGRAMMING

DATA TRANSFER INSTRUCTIONS

MOV destination, source (move byte or word data)

Example: MOV AX, [SI]

loads the data stored at the memory location addressed by

[SI] into registerAX.

PUSH source (push word onto stack)

Example: PUSH CX

places data from the source register CX into the stack.

POP destination (pop word off stack)

Example: POP DX

places data from the stack into register DX.

IN accumulator, port (input byte or word from port)

Example: IN AL, p8

8 bits are input to AL from I/O port p8.

OUT port, accumulator (output byte or word to port)

Example: OUT p8, AX

16 bits are output from AX to I/O port p8.

LEA destination, source (load effective address)Example: LEA AX, [SI]

loads the offset address specified by [SI] (contents of SI) into

AX register.

PUSHF (push flag onto stack)

POPF (pop flags off stack)

XCHG destination, source (exchange byte or word)

Example: XCHG BL, [SI]

exchanges the content of the memory location addressed by

[SI] with the content of BL.

XLAT translate_table (translate byte)

Example: MOV DL,3MOV BX, OFFSET EQUI

XLAT

MOVE SAME, DL

translate 3 into its equivalent from EQUI.


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LDS destination, source (load pointer using DS)

Example: LDS CX, [SI]

transfers the 32bit number, addressed by SI in data segment,

into the CX and DS register.

LES destination, source (load pointer using ES)

Example: LES AX, [SI]

transfers the 32bit number, addressed by SI in extra segment,

into the AX and ES register.

LAHF (load AH register from flags)

SAFH (store AH register into flags)

ARITHMETIC INSTRUCTIONS

ADD destination, source (add byte or word)

Example: ADD CL, AL

AL contents add to the contents of CL with the sum stored in

CL.

ADC destination, source (add byte or word with carry)

Example: ADC CL, CH

the byte contents of CH add to the content of CL with carry

and its sum stored in CL.

INC destination (increment byte or word by 1)

Example: INC DH

adds 1 to the content of DH.

SUB destination, source (subtract byte or word)

Example: SUB AL, DL

subtract the contents of DL from the contents of AL with the

difference stored in AL.

SBB destination, source (subtract byte or word with

borrow)

Example: SBB BL, BH

both carry and contents of BH subtract from the contents of

BL with the difference stored in BL.

DEC destination (decrement byte or word by 1)

Example: DEC AH

subtracts 1 from the byte content of AH.

CMP destination, source (compare byte or word)

Example: CMP BL, DL

DL content subtracts from the content of BL without changing

the content of the destination Usually followed by JA or JB.

MUL source (multiply byte or word unsigned)

Example: MUL DL

AL content is multiplied by DL content; The unsigned productis stored in AX.

Example: MUL BX

AX content is multiplied by BX content, The unsigned product

is stored in DX-AX


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IMUL source (integer multiply byte or word)

Example: IMUL BH

AL content is multiplied by BH content, The signed product is

stored in AX.

Example: IMUL DX

AX content is multiplied by DX content, The signed product is

stored in DX-AX.

DIV source (divide byte or word unsigned)

Example: DIV BL

AX content is divided by the content of BL, The unsigned

quotient is stored in AL and the remainder is stored in AH.

Example: DIV BX

DX-AX content is divided by the content of BX, The unsigned

quotient is stored in AX and the remainder is stored in DX.

IDIV source (integer divide byte or word)

Example: IDIV CL

AX content is divided by the content of CL, the Signed quotient

is stored in AL and the remainder is stored in AH.

Example: IDIV DI

DX-AX content is divided by the content of DI, The signed

quotient is stored in AX and the remainder is stored in DX.

NEG destination (negate byte or word)

Example: NEG BL

BL content is 2s complemented

CBW (convert byte to word)

CWD (convert word to double word)

DAA (decimal adjust for addition)

DAS (decimal adjust for subtraction)AAA (ASCII adjust for addition)

AAS (ASCII adjust for subtraction)

AAM (ASCII adjust for multiply)

AAD (ASCII adjust for division)

BIT MANIPULATION

INSTRUCTIONSNOT destination (NOT byte or word)

Example: NOT AH

AH content is 1s complemented

AND destination, source (AND byte or word)

Example: AND BL, CL

BL content is ANDed with the content of CL, result is stored in

BL.OR destination, source (OR byte or word)

Example: OR BH, DL

BH content is Ored with the content of DL, result is stored in

BH.

XOR destination, source (Exclusive-OR byte or word)

Example: XOR DH, AL


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CH content is exclusive-ORed with the, contents of AL, result is

stored in DH.

TEST destination, source (test byte or word)

Example: TEST AL, AH

content of AL is ANDed with the content of AH without

changing the destination.

BT register, bit_number

Example: BT BX, 3

Test bit position in BX. The result of the test is located in the

carry flag bit. If bit position 3 is a 1, carry is set; if bit position

4 is 0, carry is cleared.

BTC register, bit_number

Example: BTC BX, 3

Complement bit position 3 after testing it.

BTR register, bit_number

Example: BTR BX, 3

Clears bit position 3 after the test.

BTS register, bit_number

Example: BTS BX, 3

Sets bit position 3 after the test.

SHL/SAL destination, count (shift logical/arithmetic left byte or

word)

Example: SHL BX, 1

BX is logically shifted left 1 place.

Example: SAL BX, 1

BX is arithmetically shifted left 1 place.

SHR destination, count (shift logical right byte or word)

Example: SHR CX, 1

CX is logically shifted right 1 place.

0

C DATA

0

DATA C

SAR destination, count (shift arithmetic right byte or word)

Example: SAR DI, 1

DI is arithmetically shifted right 1 place.

ROL destination, count (rotate left byte or word)Example: ROL DI, 1

DI rotates left 1 place

SIGN BIT

DATA C

C DATA


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ROR destination, count (rotate right byte or word)

Example: ROR DI, 1

DI rotate right 1 place

RCL destination, count (rotate left through carry byte or word)

Example: RCL DL, 1

DL rotates left through carry 1 place

DATA C

C DATA

RCR destination, count (rotate right through carry byte

or word)

Example: RCR DH, CL

DH rotates right through carry the number of places specified

by CLDATA C

LOOP AND JUMP

INTRUCTIONS Unconditional JUMP

JMP target (unconditional jump to target)

1. Direct jump the address is given in the instruction.

2. Indirect jump the target address might be contained in a

register or a memory location.

Conditional JUMP

JNC jump if no carryJAE jump if above or equal

JNB jump if not below

JC jump if carry

JB jump if below

JNAE jump if not above nor equal

JNZ jump if not zero

JNE jump if not equal

JZ jump if zero

JE jump if equal

JNS jump if no sign

JS jump if signJNO jump if no overflow

JO jump if overflow

JNP jump if no parity

JP jump if parity


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JPE jump if parity even

JA jump if above

JBNE jump if not below nor equal

JBE jump if not below or equal

JNA jump if not above

JGE jump if greater or equal

JNL jump if not less

JL jump if less

JNGE jump if not greater nor equal

JG jump if greater

JNLE jump if not less or equal

JLE jump if less or equal

JNG jump if not greater

LOOP short-label (loop)

LOOPE/LOOPZ short-label (loop if equal/ loop if zero)

JCXZ short-label (jump if CX =0)

PROGRAM CONTROL

INSTRUCTIONSCALL PROCEDURE-NAME (call procedure)

RET optional-pop-value (return from procedure)

String instructions

A string is a series of bytes or a series of words in sequential

memory locations. A string often consists of ASCII character

codes. In the list, a / is used to separate different

mnemonics for the same instruction. Use the mnemonic

which most clearly describes the function of the instruction in

a specific application. A B In a mnemonic is used to

specifically indicate that a string of bytes is to be acted upon.

A W In the mnemonic is used to indicate that a string ofwords Is to be acted upon.

REP (An instruction prefix)

Repeat following instruction until CX = 0

REPE/REPZ (An instruction prefix)

Repeat instruction until CX = 0 or zero Flag ZF!=1


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REPNE/REPNZ (An instruction prefix)

Repeat until CX = 0 or ZF = 1

MOVS/MOVSB/MOVSW

Move byte or word from one string to another

COMPS/COMPSB/COMPSW

Compare two string bytes or two string words

INS/INSB/INSW (80186/80188)

Input string byte or word from port

OUTS/OUTSB/OUTSW (80186/80l88)

output string byte or word to port

SCAS/SCASB/SCASW

Scan a string

Compare a string byte with a byte in AL or a string word with a

word in AX

LODS/LODSB/LODSW

load string byte into AL or string word into AX

STOS/STOSB/STOSW

Store byte from AL or word from AX into string

Interrupt instructions

INT

Interrupt program execution call service procedure

INTO

Interrupt program execution OF =1

IRET

Return from interrupt se procedure to main program

High-level language interface

instructionsENTER

(80l86/80188 only) Enter procedure

LEAVE

(80l86/80188 only) Leave procedure

BOUND

(80l86/80188 only) Check effective address within specified

array bounds


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Processor controlinstructionsFlag set/clear instructions:

STC

Set carry flag CF to 1

CLC

Clear carry flag CF to 0

CMC

Complement the state of the carry flag CF

STD

Set direction flag DF to l (decrement string pointers)

CLD

Clear direction flag DF to 0

STI

Set interrupt enable flag to 1 (enable INTR input)

CLI

Clear interrupt enable flag to 0 (disable INTR input)

Execution control instructions:

HLT

Halt (do nothing) until interrupt or reset

WAIT

Wait (do nothing) until signal on the test pin is low

ESC

Escape to external coprocessor such as 8087 or 8089

LOCK

An instruction prefix. Prevents another processor from takingthe bus while the adjacent instruction executes

NOP

No action except fetch and decode

DATA MOVEMENT

INSTRUCTIONS The formats of the 8086-Pentium 4 instructions.

a. 16 bit instruction mode

b. 32 bit instruction mode

(80386 to Pentium 4 only)

OPCODE

1-2 BYTES

MOD-REG-R/M

0-1 BYTES

DISPLACEMENT

0-1BYTES

IMMEDIATE

0-2 BYTES

REGISTERSIZE

0-1 BYTES

OPCODE

1-2 BYTES

MOD-REG-R/M

0-1 BYTES

ADDRESSSIZE

0-1 BYTES

DISPLACEMENT

0-4 BYTES

IMMEDIATE

0-4 BYTES


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Override Prefixesthe first two bytes of the 32-bit instruction

mode format

Opcodeselects the operation that is performed by the

microprocessor

MOD (mode)specifies the addressing mode for selected

instruction

REG (register)registers existing in microprocessor

R/M (register/memory)registers that are enclosed with the

bracket

* specifies a register instead of a memory location in Register

addressing mode

Direction bit (D)it indicates the data flow

data flow to the register REG from the R/M field (1) or data

flow to the R/M field from the REG field (0)

W bitit indicates the size of the information

Byte size (0) or a word/double word size (1)

MOD Field for 16-bit instruction mode (Table 1)

MOD FUNCTION

00 No displacement

01 8-bit sign-extendeddisplacement

10 16-bit signed displacement

11 R/M is a register

REG and R/M (when MOD =11) assignments (Table 2)

CODE W=0(Byte) W=1 (Word) W=1 (Double word)

000 AX EAX

001 CL CX ECX

010 DL DX EDX

011 BL BX EBX

100 AH SP ESP101 CH BP EBP

110 DH SI ESI

111 BH DI EDI

16-bit R/M memory-addressing modes (Table 3)

R/M CODE ADDRESSING MODE

000 DS:[BX+SI]

001 DS:[BX+DI]

010 SS:[BP+SI]

011 SS:[BP+DI]

100 DS:[SI]101 DS:[DI]

110 SS:[BP]*

111 DS:[BX]


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* MOV CS, R/M AND POP CS ARE NOT ALLOWED (Table 4)

CODE SEGMENT REGISTER

000 ES

001 CS*

010 SS

011 DS

100 FS

101 GS

Lesson 8 Instruction Set and Programming

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