CS 301 Fall 2001

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CS 301 Fall 2001 Chapter 6

• Slides by Prof. Hartman, following IBM PC
  Assembly Language Programming by Peter Abel

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Symbolic Instructions 1Arithmetic

• ADD Add
• ADC Add with carry
• SUB Subtract
• SBB Subtract with borrow
• NEG Negate
• XADD Exchange and add
• INC Increment by 1
• DEC Decrement by 1
• MUL Unsigned multiply
• DIV Unsigned divide
• IMUL Signed multiply
• IDIV Signed divide

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Symbolic Instructions 2ASCII-BCD conversion

• AAA ASCII Adjust After Addition
• AAS ASCII Adjust After Subtraction
• AAM ASCII Adjust After Multiplication
• AAD ASCII Adjust Before Division
• DAA Decimal Adjust After Addition
• DAS Decimal Adjust After Subtraction

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Symbolic Instructions 3Bit Shifting

• RCL Rotate Left Through Carry
• RCR Rotate Right Through Carry
• ROL Rotate Left
• ROR Rotate Right
• SAL Shift Algebraic Left (SHL)
• SAR Shift Algebraic Right
• SHL Shift Logical Left (SAL)
• SHR Shift Logical Right
• SHLD Shift Left Double
• SHRD Shift Right Double

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Symbolic Instructions 4Comparison

• BSF/BSR Bit Scan
• BT/BTC/BTR/BTS Bit Test
• CMP Compare
• CMPSn Compare String
• CMPXCHG Compare and Exchange
• CMPXCHG8B Compare and Exchange
• TEST Test bits

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Symbolic Instructions 5Data Transfer

• LDS Load DS register
• LEA Load Effective Address
• LnS Load nS register
• LODS Load String
• MOV Move Data
• MOVSn Move String
• MOVSX Move with Sign-Extend
• MOVZX Move with Zero-Extend
• STOS Store String
• XCHG Exchange
• XLAT Translate

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Symbolic Instructions 6Flag Operations

• CLC/STC Clear/Set CF
• CLD/STD Clear/Set DF
• CLI/STI Clear/Set IF
• CMC Complement CF
• LAHF Load AH from Flags
• SAHF Store AH in Flags
• POPF Pop Flags Off Stack
• PUSH Push Flags On Stack

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Symbolic Instructions 7Input/Output

• IN Input Byte or Word
• OUT Output Byte or Word
• INSn Input String
• OUTSn Output String

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Symbolic Instructions 8Logical Operations

• AND Logical And
• OR Logical Or
• NOT Logical Not
• XOR Logical XOR

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Symbolic Instructions 9Looping

• LOOP Loop Until Complete
• LOOPE Loop While Equal
• LOOPZ Loop While Zero
• LOOPNE Loop While Not Equal
• LOOPNZ Loop While Not Zero

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Symbolic Instructions 10Stack Operations

• ENTER Make Stack Frame
• LEAVE Terminate Stack Frame
• POP Pop Word Off Stack
• PUSH Push Word On Stack
• POPF Pop Flags Off Stack
• PUSHF Push Flags On Stack
• POPA Pop All General Registers
• PUSHA Push All General Registers

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Symbolic Instructions 11String Operators

• CMPS Compare String
• LODS Load String
• MOVS Move String
• REP Repeat String
• REPE Repeat While Equal
• REPZ Repeat While Zero
• REPNE Repeat While Not Equal
• REPNZ Repeat While Not Zero
• SCAS Scan String
• STOS Store String

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Symbolic Instructions 12Transfer (Conditional) 1

• INTO Interrupt On Overflow
• JA Jump if Above
• JAE Jump if Above/Equal
• JB Jump if Below
• JBE Jump if Below/Equal
• JC Jump if Carry
• JCXZ Jump if CX is Zero
• JE Jump if Equal
• JG Jump if Greater
• JGE Jump if Greater/Equal
• JL Jump if Less

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Symbolic Instructions 13Transfer (Conditional) 2

• JLE Jump if Less/Equal
• JNA Jump if Not Above
• JNAE Jump if Not Above/Equal
• JNB Jump if Not Below
• JNBE Jump if Not Below/Equal
• JNC Jump if No Carry
• JNE Jump if Not Equal
• JNG Jump if Not Greater
• JNGE Jump if Not Greater/Equal
• JNL Jump if Not Less

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Symbolic Instructions 14Transfer (Conditional) 3

• JNLE Jump if Not Less/Equal
• JNO Jump if No Overflow
• JNP Jump if No Parity
• JNS Jump if No Sign
• JNZ Jump if Not Zero
• JO Jump if Overflow
• JP Jump if Parity
• JPE Jump if Parity Is Even
• JPO Jump if Parity Is Odd
• JS Jump if Sign
• JZ Jump if Zero

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Symbolic Instructions 15Transfer (Unconditional)

• CALL Call a Procedure
• INT Interrupt
• IRET Interrupt Return
• JMP Jump
• RET Return
• RETN/RETF Return Near/Far

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Symbolic Instructions 16Type Conversion

• CBW Convert Byte To Word
• CDQ Convert Doubleword to Quadword
• CWD Convert Word to DoubleWord
• CWDE Convert Word to Extended DoubleWord

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MOV Move Data

• Flags Affects no flags
• MOV reg/mem,reg/mem/imm

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ADD (and ADC/SUB/SBB)

• Add, Add with Carry, Subtract, Subtract with
  borrow.
• Flags All affect AF,CF,OF,PF,SF, and ZF
• ADD reg/mem, reg/mem/imm
• ADC reg/mem, reg/mem/imm
• SBB reg/mem, reg/mem/imm
• SUB reg/mem, reg/mem/imm

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MUL - Multiply Unsigned Integers

• Flags Affects CF and OF. (AF,PF,SF, and ZF are
  undefined)
• MUL reg/mem

Size of operand Effect
8-bit AX AL 8-bit operand
16-bit DXAX AX 16-bit operand
32-bit EDXEAX EAX 32-bit operand
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DIV - Divide Unsigned IntegersIDIV Divide
Signed Integers

• Flags Affect AF,CF,OF,PF,SF, and ZF (all
  undefined)
• DIV reg/mem
• IDIV reg/mem

Size of operand Operation Quotient Remainder
8-bit AX/operand AL AH
16-bit (DXAX)/operand AX DX
32-bit (EDXEAX)/operand EAX EDX
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IMUL Multiply Signed Integers

• Flags Affects CF and OF. (AF,PF,SF, and ZF are
  undefined)

Format Format Format Format Effect
dest source1 source2 Effect
IMUL reg/mem8 AX AL source1
IMUL reg/mem16 DXAX AX source1
IMUL reg/mem32 EDXEAX EAX source1
IMUL reg reg/mem/imm dest source1
IMUL reg reg/mem imm dest source1 source2
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Some Examples

• Assembled ADD instructions
• math.asm
• prime.asm