Skip to content

Latest commit

 

History

History
658 lines (471 loc) · 12.3 KB

ISA.md

File metadata and controls

658 lines (471 loc) · 12.3 KB
Raw

80[_12]86 ISA

For more informations about x86 opcodes, you can read the following documents:

and so many others... (i'll try to list them as i go)

Table of contents:

Operands

  • GENERAL PURPOSE REGISTERS: AH, AL, BL, BH, CH, CL, DH, DL, AX, BX, CX, DX, DI, SI, BP, SP.

  • FLAGS: CF, PF, AF, ZF, SF, TF, IF, DF, OF.

  • SEGMENT REGISTERS: DS, ES, SS, and only as second operand: CS.

  • MEMORY ADDRESSING: [BX+SI], [BX+DI], [BP+SI], [BP+DI], [SI], [DI], [BP], [BX] (todo)

  • IMMEDIATE VALUE: 8 or 16 bits : 0x12, 0x1234, etc.

Flags

  • CF - Carry flag

This flag is set if the last arithmetic operation generated a carry or a borrow.

  • PF - Parity flag

This flag is set if the last arithmetic operation generated an even number of 1-bits in the result.

  • AF - Auxiliary carry flag

This flag is set if the last arithmetic operation generated a carry or borrow from bit 3 to bit 4. Todo: play with BCD and this flag.

  • ZF - Zero flag

This flag is set if the last arithmetic or logical operation generated a zero result.

  • SF - Sign flag

This flag is set if the last arithmetic or logical operation generated a negative result.

  • TF - Trap flag

This flags puts the processor in single step mode for debugging. In this mode, the processor will generate an interrupt after each instruction.

  • IF - Interrupt flag

This flag enables or disables interrupts.

  • DF - Direction flag

This flag is used in string instructions to determine the direction of the operation.

  • OF - Overflow flag

This flag is set if the last arithmetic operation generated an overflow.

Instructions

  • [-] AAA - ASCII adjust after addition
  • [-] AAD - ASCII adjust after division
  • [-] AAM - ASCII adjust after multiplication
  • [-] AAS - ASCII adjust after subtraction
  • [-] ADC - Add with carry
  • [-] ADD - Add
  • [-] AND - And
  • [-] CALL - Call
  • [-] CBW - Convert byte to word
  • [-] CLC - Clear carry flag
  • [-] CLD - Clear direction flag
  • [-] CLI - Clear interrupt flag
  • [-] CMC - Complement carry flag
  • [-] CMP - Compare
  • CMPS - Compare strings
    • CMPSB - Compare strings byte
    • CMPSW - Compare strings word
  • [-] CWD - Convert word to double word
  • DAA - Decimal adjust after addition
  • DAS - Decimal adjust after subtraction
  • DEC - Decrement
  • DIV - Divide
  • [-] HLT - Halt
  • IDIV
  • IMUL - Integer multiply
  • IN - Input
  • INC - Increment
  • INT - Interrupt
  • INTO - Interrupt on overflow
  • IRET - Interrupt return
  • Jcc - Jump if condition
    • JA
    • JAE
    • JB
    • JBE
    • JC
    • JCXZ
    • JE
    • JG
    • JGE
    • JL
    • JLE
    • JMP
    • JNA
    • JNAE
    • JNB
    • JNBE
    • JNC
    • JNE
    • JNG
    • JNGE
    • JNL
    • JNLE
    • JNO
    • JNP
    • JNS
    • JNZ
    • JO
    • JP
    • JPE
    • JPO
    • JS
    • JZ
  • LAHF - Load AH from flags
  • LDS - Load DS from memory
  • LEA - Load effective address
  • LES - Load ES from memory
  • LODS - Load string
    • LODSB - Load string byte
    • LODSW - Load string word
  • LOOP - Loop
  • LOOPE - Loop if equal
  • LOOPNE - Loop if not equal
  • LOOPNZ - Loop if not zero
  • LOOPZ - Loop if zero
  • MOV - Move
    • MOVSB - Move string byte
    • MOVSW - Move string word
  • MUL - Multiply
  • NEG - Negate
  • [-] NOP - No operation
  • NOT - Not
  • [-] OR - Or
  • OUT - Output
  • [-] POP - Pop
  • POPA - Pop all
  • POPF - Pop flags
  • [-] PUSH - Push
  • PUSHA - Push all
  • PUSHF - Push flags
  • RCL - Rotate left through carry
  • RCR - Rotate right through carry
  • REP - Repeat
  • REPE - Repeat if equal
  • REPNE - Repeat if not equal
  • REPNZ - Repeat if not zero
  • REPZ - Repeat if zero
  • [-] RET - Return
  • RETF - Return from far
  • ROL - Rotate left
  • ROR - Rotate right
  • SAHF - Store AH from flags
  • SAL - Shift arithmetic left
  • SAR - Shift arithmetic right
  • SBB - Subtract with borrow
  • SCAS - Scan string
    • SCASB - Scan string byte
    • SCASW - Scan string word
  • SHL - Shift logical left
  • SHR - Shift logical right
  • [-] (STC)[#stc---set-carry-flag] - Set carry flag
  • [-] STD - Set direction flag
  • [-] STI - Set interrupt flag
  • STOS - Store string
    • STOSB - Store string byte
    • STOSW - Store string word
  • [-] SUB - Subtract
  • TEST - Test
  • XCHG - Exchange
  • XLATB - Translate byte
  • [-] XOR - Exclusive or

Instruction by kind

Data transfer instructions

General purpose

  • MOV
  • PUSH
  • POP
  • PUSHA
  • POPA
  • XCHG
  • XLATB

Input/Output

  • IN
  • OUT

Address object and stack frame

  • LEA
  • LDS
  • LES
  • ENTER (added in 80186)
  • LEAVE (added in 80186)

Flag transfer

  • LAHF
  • SAHF
  • PUSHF
  • POPF

Arithmetic instructions

Addition

  • ADD
  • ADC
  • INC
  • AAA
  • DAA

Subtraction

  • SUB
  • SBB
  • DEC
  • NEG
  • CMP
  • AAS
  • DAS

Multiplication

  • MUL
  • IMUL
  • AAM

Division

  • DIV
  • IDIV
  • AAD

Conversion

  • CBW
  • CWD

todo: maybe we can put aaa, aad, aam, aas in the same section ???

Bit manipulation

Logical

  • AND
  • OR
  • XOR
  • NOT
  • TEST

Shift

  • SHL/SAL
  • SHR
  • SAR

Rotate

  • ROL
  • ROR
  • RCL
  • RCR

String

  • REP
  • REPE/REPZ
  • REPNE/REPNZ
  • MOVSB/MOVSW
  • CMPSB/CMPSW
  • SCASB/SCASW
  • LODSB/LODSW
  • STOSB/STOSW

Control instructions

Conditional

  • Jcc

Unconditionnal

  • CALL
  • RET
  • JMP

Iteration control

  • LOOP
  • LOOPE/LOOPZ
  • LOOPNE/LOOPNZ
  • JCXZ

Interrupt

  • INT
  • INTO
  • IRET
  • BOUND (introduced in 80286 ???)

Processor control

Flag operations

  • CLC
  • CLD
  • CLI
  • CMC
  • STC
  • STD
  • STI

External synchronization

  • HLT
  • WAIT
  • ESC
  • LOCK

No operation

  • NOP

Instructions details

AAA - ASCII adjust after addition

Opcode: 37

if (AL AND 0FH) > 9 or AF = 1 then:
    AL = AL + 6
    AH = AH + 1
    AF = 1
    CF = 1
else:
    AF = 0
    CF = 0
AL = AL AND 0FH

See example in tests/isa/aaa.asm

AAD - ASCII adjust after division

Opcode: D5 ib

AL = (AL + AH * ib) AND 0FH
AH = 0

See example in tests/isa/aad.asm

AAM - ASCII adjust after multiplication

Opcode: D4 ib

tempAL = AL
AL = (tempAL * ib) AND 0FH
AH = tempAL / ib

See example in tests/isa/aam.asm

AAS - ASCII adjust after subtraction

Opcode: 3F

if (AL AND 0FH) > 9 or AF = 1 then:
    AX = AX – 6
    AH = AH – 1
    AF = 1
    CF = 1
    AL = AL AND 0FH
else:
    AF = 0
    CF = 0
    AL = AL AND 0FH

See example in tests/isa/aas.asm

ADC - Add with carry

Opcodes:

bytes mnemonic note
10 r/m ADC r/m8, r8
11 r/m ADC r/m16, r16
12 r/m ib ADC r/m8, imm8
13 r/m iw ADC r/m16, imm16
14 ib ADC AL, imm8
15 iw ADC AX, imm16
80 /2 ib ADC r/m8, imm8
81 /2 iw ADC r/m16, imm16
82 /2 ib ADC r/m8, imm8 todo: not in all x86 processors, same as 80 /2 ib
83 /2 iw ADC r/m16, imm16 
dst = dst + src + (CF ? 1 : 0)

See example in tests/isa/adc.asm

ADD - Add

Opcodes:

bytes mnemonic
00 r/m ADD r/m8, r8
01 r/m ADD r/m16, r16
02 r/m ADD r/m8, imm8
03 r/m ADD r/m16, imm16
04 ib ADD AL, imm8
05 iw ADD AX, imm16
04 ib ADC AL, imm8
05 iw ADC AX, imm16
80 /0 ib ADC r/m8, imm8
81 /0 iw ADC r/m16, imm16
82 /0 ib ADC r/m8, imm8
83 /0 iw ADC r/m16, imm16 
dst = dst + src

See example in tests/isa/add.asm

AND - And

CALL - Call

CBW - Convert byte to word

CLC - Clear carry flag

CLD - Clear direction flag

CLI - Clear interrupt flag

CMC - Complement carry flag

CMP - Compare

CMPS - Compare strings

CWD - Convert word to double word

DAA - Decimal adjust after addition

DAS - Decimal adjust after subtraction

DEC - Decrement

DIV - Divide

HLT - Halt

IDIV

IMUL - Integer multiply

IN - Input

INC - Increment

INT - Interrupt

INTO - Interrupt on overflow

IRET - Interrupt return

Jcc - Jump if condition

LAHF - Load AH from flags

LDS - Load DS from memory

LEA - Load effective address

LES - Load ES from memory

LODS - Load string

LOOP - Loop

LOOPE - Loop if equal

LOOPNE - Loop if not equal

LOOPNZ - Loop if not zero

LOOPZ - Loop if zero

MOV - Move

MUL - Multiply

NEG - Negate

NOP - No operation

NOT - Not

OR - Or

OUT - Output

POP - Pop

POPA - Pop all

POPF - Pop flags

PUSH - Push

PUSHA - Push all

PUSHF - Push flags

RCL - Rotate left through carry

RCR - Rotate right through carry

REP - Repeat

REPE - Repeat if equal

REPNE - Repeat if not equal

REPNZ - Repeat if not zero

REPZ - Repeat if zero

RET - Return

RETF - Return from far

ROL - Rotate left

ROR - Rotate right

SAHF - Store AH from flags

SAL - Shift arithmetic left

SAR - Shift arithmetic right

SBB - Subtract with borrow

SCAS - Scan string

SHL - Shift logical left

SHR - Shift logical right

STC - Set carry flag

STD - Set direction flag

STI - Set interrupt flag

STOS - Store string

SUB - Subtract

TEST - Test

XCHG - Exchange

XLATB - Translate byte

XOR - Exclusive or

Instruction by

Opcode map

low nibble

-0 -1 -2 -3 -4 -5 -6 -7
0- ADD r/m8, r8 ADD r/m8, r8 ADD r/m8, imm8 ADD r/m8, imm16 ADD AL, imm8 ADD AX, imm16
1- ADC r/m8, r8 ADC r/m8, r8 ADC r/m8, imm8 ADC r/m8, imm16 ADC AL, imm8 ADC AX, imm16
2- AND r/m8, r8 AND r/m8, r8 AND r/m8, imm8 AND r/m8, imm16 AND AL, imm8 AND AX, imm16
3- XOR r/m8, r8 XOR r/m8, r8 XOR r/m8, imm8 XOR r/m8, imm16 XOR AL, imm8 XOR AX, imm16 AAA
4-
5-
6-
7-
-8 -9 -A -B -C -D -E -F
0- OR r/m8, r8 OR r/m8, r8 OR r/m8, imm8 OR r/m8, imm16 OR AL, imm8 OR AX, imm16
1- SBB r/m8, r8 SBB r/m8, r8 SBB r/m8, imm8 SBB r/m8, imm16 SBB AL, imm8 SBB AX, imm16
2- SUB r/m8, r8 SUB r/m8, r8 SUB r/m8, imm8 SUB r/m8, imm16 SUB AL, imm8 SUB AX, imm16
3- CMP r/m8, r8 CMP r/m8, r8 CMP r/m8, imm8 CMP r/m8, imm16 CMP AL, imm8 CMP AX, imm16 AAS
4-
5-
6-
7-

high nibble

-0 -1 -2 -3 -4 -5 -6 -7
8-
9-
A-
B-
C-
D- AAM imm8 AAD imm8
E-
F-
-8 -9 -A -B -C -D -E -F
8-
9-
A-
B-
C-
D-
E-
F-