Pengantar Organisasi Komputer

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IKI10230Pengantar Organisasi KomputerKuliah no.
05.b Arithmetic Operations
Sumber1. Paul Carter, PC Assembly Language2.
Hamacher. Computer Organization, ed-53. Materi
kuliah CS61C/2000 CS152/1997, UCB4. Intel
Architecture Software Developers Manual
17 Maret 2004 L. Yohanes Stefanus
(yohanes_at_cs.ui.ac.id)Bobby Nazief
(nazief_at_cs.ui.ac.id) bahan kuliah
http//www.cs.ui.ac.id/kuliah/POK/
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Arithmetic Instructions

• The binary arithmetic instructions
• operate on 8-, 16-, and 32-bit numeric data
• encoded as signed or unsigned binary integers
• Operations include
• add,
• subtract,
• multiply,
• divide
• increment, decrement, compare, and change sign
  (negate)
• The are also BCD (binary coded decimal)
  arithmetic instructions

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Arithmetic Instructions Summary

• ADD Integer add
• ADC Add with carry
• SUB Subtract
• SBB Subtract with borrow
• IMUL Signed multiply
• MUL Unsigned multiply
• IDIV Signed divide
• DIV Unsigned divide
• INC Increment
• DEC Decrement
• NEG Negate
• CMP Compare
• DAA Decimal adjust after addition
• DAS Decimal adjust after subtraction
• AAA ASCII adjust after addition

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Additions Subtractions

• ADD DEST,SRC DEST ? DEST SRC
• OF, SF, ZF, AF, CF, and PF flags are set
  according to the result
• ADC DEST,SRC DEST ? DEST SRC CF
• OF, SF, ZF, AF, CF, and PF flags are set
  according to the result
• SUB DEST,SRC DEST ? DEST - SRC
• OF, SF, ZF, AF, CF, and PF flags are set
  according to the result
• SBB DEST,SRC DEST ? DEST - SRC CF
• OF, SF, ZF, AF, CF, and PF flags are set
  according to the result

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Format Instruksi ADD, ADC, SUB, SBB

• ACC ? ACC IMM
• ADD AL,imm8 Add imm8 to AL
• ADD AX,imm16 Add imm16 to AX
• ADD EAX,imm32 Add imm32 to EAX
• REG/MEM ? REG/MEM IMM
• ADD r/m8,imm8 Add imm8 to r/m8
• ADD r/m16,imm16 Add imm16 to r/m16
• ADD r/m32,imm32 Add imm32 to r/m32
• ADD r/m16,imm8 Add sign-extended imm8 to r/m16
• ADD r/m32,imm8 Add sign-extended imm8 to r/m32
• REG/MEM ? REG/MEM REG
• ADD r/m8,r8 Add r8 to r/m8
• ADD r/m16,r16 Add r16 to r/m16
• ADD r/m32,r32 Add r32 to r/m32
• REG ? REG REG/MEM
• ADD r8,r/m8 Add r/m8 to r8
• ADD r16,r/m16 Add r/m16 to r16
• ADD r32,r/m32 Add r/m32 to r32

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Multiplication

• MUL SRC DEST ? ACC SRC
• The MUL instruction multiplies two unsigned
  integer operands.
• SRC ACC DEST
• r/m8 AL AX
• r/m16 AX DXAX
• r/m32 EAX EDXEAX
• CF OF flags are set to 0 if the upper half of
  the result is 0 otherwise, they are set to 1
• IMUL
• IMUL SRC lihat MUL SRC
• IMUL DEST,SRC DEST ? DEST SRC
• The IMUL instruction multiplies two signed
  integer operands.
• CF OF flags are set when
• significant bits are carried into the upper half
  of the result
• the result must be truncated to fit in the
  destination operand size

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Format Instruksi MUL

• MUL r/m8 Unsigned multiply (AX ? AL
  REG/MEM)
• MUL r/m16 Unsigned multiply (DXAX ? AX
  REG/MEM)
• MUL r/m32 Unsigned multiply (EDXEAX ? EAX
  REG/MEM)

• CONTOH
• MUL DL
• MUL BYTE DATA
• MUL DX
• MUL WORD DATA
• MUL EDX
• MUL DWORD DATA

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Format Instruksi IMUL

• 1-OPERAND
• IMUL r/m8 AX? AL REG/MEM
• IMUL r/m16 DXAX ? AX REG/MEM
• IMUL r/m32 EDXEAX ? EAX REG/MEM
• 2-OPERAND
• IMUL r16,r/m16 REG ? REG REG/MEM
• IMUL r16,imm8 REG ? REG sign-extended IMM
• IMUL r16,imm16 REG ? r/m16 IMM
• IMUL r32,r/m32 REG ? REG REG/MEM
• IMUL r32,imm8 REG ? REG sign-extended IMM
• IMUL r32,imm32 REG ? REG/MEM IMM
• 3-OPERAND
• IMUL r16,r/m16,imm8 REG ? REG/MEM sign-ext.
  IMM
• IMUL r16,r/m16,imm16 REG ? REG/MEM IMM
• IMUL r32,r/m32,imm8 REG ? REG/MEM sign-ext.
  IMM
• IMUL r32,r/m32,imm32 REG ? REG/MEM IMM

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Division

• DIV SRC QUO. REM. ? ACC / SRC
• divides one unsigned integer operand (ACC) by
  another (SRC)
• SRC ACC QUOTIENT REMAINDER
• r/m8 AX AL AH
• r/m16 DXAX AX DX
• r/m32 EDXEAX EAX EDX
• non-integral results are truncated (chopped)
  towards 0
• remainder is always less than the divisor in
  magnitude
• overflow is indicated with the DE (divide error)
  exception rather than with the OF flag
• IDIV SRC QUO. REM. ? ACC / SRC
• divides one signed integer operand (ACC) by
  another (SRC)
• non-integral results are truncated (chopped)
  towards 0
• sign of the remainder is always the same as the
  sign of the dividend
• absolute value of the remainder is always less
  than the absolute value of the divisor
• overflow is indicated with the DE (divide error)
  exception rather than with the OF (overflow) flag

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Format Instruksi DIV IDIV

• Unsigned Divide
• DIV r/m8 QAL, RAH ? AX / REG/MEM
• DIV r/m16 QAX, RDX ? DXAX / REG/MEM
• DIV r/m32 QEAX, REDX ? EDXEAX / REG/MEM
• Signed Divide
• IDIV r/m8 QAL, RAH ? AX / REG/MEM
• IDIV r/m16 QAX, RDX ? DXAX / REG/MEM
• IDIV r/m32 QEAX, REDX ? EDXEAX / REG/MEM

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INC DEC

• INC DEST DEST ? DEST 1
• DEC DEST DEST ? DEST 1
• Operand is assumed to be unsigned integer.
• CF flag is not affected. OF, SF, ZF, AF, and PF
  flags are set according to the result.
• INC/DEC r/m8 Increment r/m byte by 1
• INC BYTE DATA
• INC/DEC r/m16 Increment r/m word by 1
• INC WORD DATA
• INC/DEC r/m32 Increment r/m doubleword by 1
• INC DWORD DATA
• INC/DEC r16 Increment word register by 1
• INC/DEC r32 Increment doubleword register by 1

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CMP NEG

• CMP DEST,SRC DEST SRC, update FLAGS
• The source operands are not modified, nor is the
  result saved.
• The CF, OF, SF, ZF, AF, and PF flags are set
  according to the result (in the same manner as
  the SUB instruction)
• NEG DEST DEST ? 0 DEST
• Assume a signed integer operand
• CF flag set to 0 if the source operand is 0
  otherwise it is set to 1
• OF, SF, ZF, AF, and PF flags are set according to
  the result

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Format Instruksi CMP

• ACC - IMM
• CMP AL, imm8 Compare imm8 with AL
• CMP AX, imm16 Compare imm16 with AX
• CMP EAX, imm32 Compare imm32 with EAX
• REG/MEM - IMM
• CMP r/m8, imm8 Compare imm8 with r/m8
• CMP r/m16, imm16 Compare imm16 with r/m16
• CMP r/m32,imm32 Compare imm32 with r/m32
• CMP r/m16,imm8 Compare imm8 with r/m16
• CMP r/m32,imm8 Compare imm8 with r/m32
• REG/MEM REG
• CMP r/m8,r8 Compare r8 with r/m8
• CMP r/m16,r16 Compare r16 with r/m16
• CMP r/m32,r32 Compare r32 with r/m32
• REG REG/MEM
• CMP r8,r/m8 Compare r/m8 with r8
• CMP r16,r/m16 Compare r/m16 with r16
• CMP r32,r/m32 Compare r/m32 with r32

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Format Instruksi NEG

• NEG r/m8 Twos complement negate r/m8
• NEG r/m16 Twos complement negate r/m16
• NEG r/m32 Twos complement negate r/m32

• CONTOH
• NEG DL
• NEG BYTE DATA
• NEG DX
• NEG WORD DATA
• NEG EDX
• NEG DWORD DATA

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• DECIMAL ARITHMETIC

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Packed Unpacked BCD Integers

• Binary-coded decimal integers (BCD integers) are
  unsigned 4-bit integers with valid values ranging
  from 0 to 9.
• BCD integers can be unpacked (one BCD digit per
  byte) or packed (two BCD digits per byte).
• The value of an unpacked BCD integer is the
  binary value of the low halfbyte (bits 0 through
  3).
• The high half-byte (bits 4 through 7) can be any
  value during addition and subtraction, but must
  be zero during multiplication and division.
• Packed BCD integers allow two BCD digits to be
  contained in one byte.
• Here, the digit in the high half-byte is more
  significant than the digit in the low half-byte.

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Decimal Arithmetic

• Decimal arithmetic can be performed by combining
  the binary arithmetic instructions ADD, SUB, MUL,
  and DIV with the decimal arithmetic instructions.
• The decimal arithmetic instructions are provided
  to carry out the following operations
• To adjust the results of a previous binary
  arithmetic operation to produce a valid BCD
  result.
• To adjust the operands of a subsequent binary
  arithmetic operation so that the operation will
  produce a valid BCD result.
• Decimal arithmetic instructions operate only on
  both packed and unpacked BCD values.

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Packed-BCD Instructions

• The DAA (decimal adjust after addition) and DAS
  (decimal adjust after subtraction) instructions
  adjust the results of operations performed on
  packed BCD integers.
• Adding two packed BCD values requires two
  instructions
• an ADD instruction adds (binary addition) the
  two values and stores the result in the AL
  register
• followed by a DAA instruction adjusts the value
  in the AL register to obtain a valid, 2-digit,
  packed BCD value and sets the CF flag if a
  decimal carry occurred as the result of the
  addition.
• Subtracting one packed BCD value from another
  requires
• a SUB instruction subtracts (binary subtraction)
  one BCD value from another and stores the result
  in the AL register
• followed by a DAS instruction adjusts the value
  in the AL register to obtain a valid, 2-digit,
  packed BCD value and sets the CF flag if a
  decimal borrow occurred as the result of the
  subtraction.

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Unpacked-BCD Instructions

• AAA (ASCII adjust after addition)
• converts the binary value in the AL register into
  a decimal value and stores the result in the AL
  register in unpacked BCD format
• if a decimal carry occurred as a result of the
  addition, the CF flag is set and the contents of
  the AH register are incremented by 1
• AAS (ASCII adjust after subtraction)
• similar with AAA
• AAM (ASCII adjust after multiplication)
• converts the binary value in the AL register into
  a decimal value and stores the least significant
  digit of the result in the AL register and the
  most significant digit, if there is one, in the
  AH register
• AAD (ASCII adjust before division)
• converts the BCD value in registers AH (most
  significant digit) and AL (least significant
  digit) into a binary value and stores the result
  in register AL
• when the value in AL is divided by an unpacked
  BCD value, the quotient and remainder will be
  automatically encoded in unpacked BCD format

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Contoh Program math.asm (1/5)

• include "asm_io.inc"
• segment .data
• Output strings
• prompt db "Enter a number ", 0
• square_msg db "Square of input is ", 0
• cube_msg db "Cube of input is ", 0
• cube25_msg db "Cube of input times 25 is ", 0
• quot_msg db "Quotient of cube/100 is
  ", 0
• rem_msg db "Remainder of cube/100 is
  ", 0
• neg_msg db "The negation of the
  remainder is ", 0
• segment .bss
• input resd 1

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Contoh Program math.asm (2/5)

• segment .text
• global _asm_main
• _asm_main
• enter 0,0 setup
  routine
• pusha
• mov eax, prompt
• call print_string
• call read_int
• mov input, eax
• imul eax edxeax
  eax eax
• mov ebx, eax save answer
  in ebx
• mov eax, square_msg
• call print_string
• mov eax, ebx
• call print_int
• call print_nl

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Contoh Program math.asm (3/5)

• mov ebx, eax
• imul ebx, input ebx input
• mov eax, cube_msg
• call print_string
• mov eax, ebx
• call print_int
• call print_nl
• imul ecx, ebx, 25 ecx ebx25
• mov eax, cube25_msg
• call print_string
• mov eax, ecx
• call print_int
• call print_nl

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Contoh Program math.asm (4/5)

• mov eax, ebx
• cdq initialize
  edx by sign extension
• mov ecx, 100 can't divide
  by immediate value
• idiv ecx edxeax /
  ecx
• mov ecx, eax save quotient
  into ecx
• mov eax, quot_msg
• call print_string
• mov eax, ecx
• call print_int
• call print_nl
• mov eax, rem_msg
• call print_string
• mov eax, edx
• call print_int
• call print_nl

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Contoh Program math.asm (5/5)

• neg edx negate the
  remainder
• mov eax, neg_msg
• call print_string
• mov eax, edx
• call print_int
• call print_nl
• popa
• mov eax, 0 return back to
  C
• leave
• ret

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• math.exe