3.1 DATA MOVEMENT INSTRUCTIONS 45

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1 3.1.1 General-Purpose Data Movement s Stack Manipulation Type Conversion Addition and Subtraction DATA MOVEMENT INSTRUCTIONS 45 MOV (Move) transfers a byte, word, or doubleword from the source operand to the destination operand XCHG (Exchange) swaps the contents of two operands. PUSH (Push) decrements the stack pointer (ESP), then transfers the source operand to the top of stack indicated by ESP PUSHA (Push All Registers) saves the contents of the eight general registers on the stack POP (Pop) transfers the word or doubleword at the current top of stack indicated by ESP) to the destination operand, and then increments ESP to point to the new top of stack POPA (Pop All Registers) restores the registers saved on the stack by PUSHA, except that it ignores the saved value of ESP. CWD (Convert Word to Doubleword) and CDQ CDQ (Convert Doubleword to Quad-Word) CBW (Convert Byte to Word) extends the sign of the byte in register AL throughout AX. CWDE (Convert Word to Doubleword Extended) extends the sign of the word in register AX throughout EAX. MOVSX (Move with Sign Extension) sign-extends an 8-bit value to a 16-bit value and a 8- or 16-bit value to 32-bit value. MOVZX (Move with Zero Extension) extends an 8-bit value to a 16-bit value and an 8- or 16-bit value to 32-bit value by inserting high-order zeros. 3.2 BINARY ARITHMETIC INSTRUCTIONS ADD (Add Integers) replaces the destination operand with the sum of the source and destination operands. Sets CF if overflow. ADC (Add Integers with Carry) sums the operands, adds one if CF is set, and replaces the destination operand with the result. INC (Increment) adds one to the destination operand (Subtract Integers) subtracts the source operand from the destination SUB operand and replaces the destination operand with the result If a borrow is required, the CF is set. (Subtract Integers with Borrow) subtracts the source operand from the SBB destination operand, subtracts 1 if CF is set, and returns the result to the destination operand.

2 3.2.2 Comparison and Sign Change Multiplication Division Packed BCD Adjustment Unpacked BCD Adjustment Boolean Operation DEC (Decrement) subtracts 1 from the destination operand. (Compare) subtracts the source operand from the destination operand. It CMP updates OF, SF, ZF, AF, PF, and CF but does not alter the source and destination operands. NEG (Negate) subtracts a signed integer operand from zero. (Unsigned Integer Multiply) performs an unsigned multiplication of the MUL source operand and the accumulator IMUL (Signed Integer Multiply) performs a signed multiplication operation. (Unsigned Integer Divide) performs an unsigned division of the DIV accumulator by the source operand. (Signed Integer Divide) performs a signed division of the accumulator IDIV by the source operand. IDIV uses the same registers as the DIV instruction 3.3 DECIMAL ARITHMETIC INSTRUCTIONS. 53 (Decimal Adjust after Addition) adjusts the result of adding two valid DAA packed decimal operands in AL. Corrects the result of addition of two packed BCD values. (Decimal Adjust after Subtraction) adjusts the result of subtracting DAS two valid packed decimal operands in AL. (ASCII Adjust after Addition) changes the contents of register AL to a AAA valid unpacked decimal number, and zeros the top 4 bits. Corrects result in AH and AL after addition when working with BCD values. (ASCII Adjust after Subtraction) changes the contents of register AL to AAS a valid unpacked decimal number, and zeros the top 4 bits. (ASCII Adjust after Multiplication) corrects the result of a AAM multiplication of two valid unpacked decimal numbers. (ASCII Adjust before Division) modifies the numerator in AH and AL to AAD prepare for the division of two valid unpacked decimal operands so that the quotient produced by the division will be a valid unpacked decimal number. 3.4 LOGICAL INSTRUCTIONS (Not) inverts the bits in the specified operand to form a one's NOT complement of the operand. AND, instructions perform the standard logical operations OR,XOR "and", "(inclusive) or", and "exclusive or"

3 3.4.2 Bit Test and Modify Bit Scan Shift and Rotate Shift Double-Shift Rotate BT,BTS, BTR,BTC BSF BSR SAL/SHL SHR SAR SHLD SHRD ROL ROR These instructions first assign the value of the selected bit to CF, the carry flag. Then a new value is assigned to the selected bit, as determined by the operation. Instruction Effect on CF Effect on Selected Bit BT (Bit Test) CF BIT (none) BTS (Bit Test and Set) CF BIT BIT 1 BTR (Bit Test and Reset) CF BIT BIT 0 BTC (Bit Test and Complement) CF BIT BIT NOT(BIT) (Bit Scan Forward) scans from low-order to high-order (starting from bit index zero) If the bits are all zero, ZF is cleared. Otherwise, ZF is set (Bit Scan Reverse) scans from high-order to low-order (starting from bit index 15 of a word or index 31 of a doubleword). (Shift Arithmetic Left) shifts the destination byte, word, or doubleword operand left by one or by the number of bits specified in the count operand (Shift Logical Right) shifts the destination byte, word, or doubleword operand right by one or by the number of bits specified in the count operand (Shift Arithmetic Right) shifts the destination byte, word, or doubleword operand to the right by one or by the number of bits specified in the count operand. Sign bit is preserved (Shift Left Double) SHLD dest,src,count shifts "dest" to the left "count" times and the bit positions opened are filled with the most significant bits of "src". (Shift Right Double) SHRD dest,src,count shifts "dest" to the right "count" times and the bit positions opened are filled with the least significant bits of the second operand. Only the 5 lower bits of "count" are used. (Rotate Left) rotates the byte, word, or doubleword destination operand left by one or by the number of bits specified in the count operand (an immediate value or the value contained in CL) (Rotate Right) rotates the byte, word, or doubleword destination operand right by one or by the number of bits specified in the count operand (an immediate value or the value contained in CL).

4 Rotate (Rotate Through Carry Left) rotates bits in the byte, word, or doubleword destination RCL operand left by one or by the number of bits specified in the count operand (an immediate value or the value contained in CL). (Rotate Through Carry Right) rotates bits in the byte, word, or doubleword RCR destination operand right by one or by the number of bits specified in the count operand (an immediate value or the value contained in CL) Byte-Set-On-Condition 64 SET cc (Set Byte on Condition cc) set a byte to one if condition cc is true; sets the byte to zero otherwise Test 64 TEST (Test) performs the logical "and" of the two operands, clears OF and CF, leaves AF undefined, and updates SF, ZF, and PF. 3.5 CONTROL TRANSFER INSTRUCTIONS JMP, CALL, RET, INT and IRET instructions transfer control from one code Unconditional Transfer segment location to another. These locations can be within the same code segment (near control transfers) or in different code segments (far control transfers) Jump. 65 JMP (Jump) unconditionally transfers control to the target location. JMP is a one-way transfer of execution; it does not save a return address on the stack Call CALL (Call Procedure) activates an out-of-line procedure, saving on the stack the address of the instruction following the CALL for later use by a RET (Return) instruction Return and Return-From-Interrupt RET (Return From Procedure) terminates the execution of a procedure and transfers control through a back-link on the stack to the program that originally invoked the procedure Conditional Transfer Conditional Jump 67 LOOP (Loop While ECX Not Zero) is a conditional transfer that automatically decrements the ECX register before testing ECX for the branch condition. (Loop While Equal) and LOOPZ (Loop While Zero) are synonyms for the same instruction. These instructions automatically decrement the ECX LOOPE register before testing ECX and ZF for the branch conditions. If ECX is Loop 67 non-zero and ZF=1, the program branches to the target label (Loop While Not Equal) and LOOPNZ (Loop While Not Zero) are synonyms for the LOOPNE same instruction. These instructions automatically decrement the ECX register before testing ECX and ZF for the branch conditions. If ECX is non-zero and ZF=0, the program branches to the target label

5 Executing a Loop or Repeat Zero Times.. (Jump if ECX Zero) branches to the label specified in the instruction JCXZ 68 if it finds a value of zero in ECX. INT n (Software Interrupt) activates the interrupt service routine that corresponds to the number coded within the instruction Software-Generated Interrupts INTO (Interrupt on Overflow) invokes interrupt 4 if OF is set. Interrupt 4 is reserved for this purpose BOUND (Detect Value Out of Range) verifies that the signed value contained in the specified register lies within specified limits. 3.6 STRING AND CHARACTER TRANSLATION INSTRUCTIONS Repeat prefixes Repeat Prefixes 70 REP REP Repeat while ECX not xero REPE/REPZ Repeat while equal or zero (ZF = 0) REPNE/REPNZ Repeat while not equal or not zero (ZF = 1) Indexing and Direction Flag Control CLD, STD Control flag instructions: CLD Clear direction flag instruction STD Set direction flag instruction MOVS Move String moves the string element pointed to by ESI to the location pointed to by EDI CMPS Compare string Subtracts destination value from source without saving results. Updates flags based on the subtraction and the index registers (E)SI and (E)DI are incremented or decremented depending on the state of the Direction Flag String Scan string SCAS subtracts the destination string element at ES:EDI from EAX, AX, or AL and updates the flags AF, SF, ZF, PF, CF and OF. Load string LODS places the source string element at ESI into EAX for doubleword strings, into AX for word strings, or into AL for byte strings. STOS Store string places the source string element from EAX, AX, or AL into the string at ES:DSI. 3.7 INSTRUCTIONS FOR BLOCK-STRUCTURED LANGUAGES (Enter Procedure) creates a stack frame that may be used to implement the scope ENTER rules of block-structured high-level languages. Modifies stack for entry to procedure Block Structured..72 for high level language.

6 Block Structured..72 (Restore Stack for Procedure Exit )instruction at the end of a procedure LEAVE complements an ENTER at the beginning of the procedure to simplify stack management and to control access to variables for nested procedures. 3.8 FLAG CONTROL INSTRUCTIONS STC (Set Carry Flag) CF 1 STC, CLC CLC (Clear Carry Flag) CF Carry and Direction Flag Control 79,CMC,CLD, CMC (Complement Carry Flag) CF NOT (CF) STD CLD (Clear Direction Flag) DF 0 STD (Set Direction Flag) DF 1 LAHF (Load AH from Flags) copies SF, ZF, AF, PF, and CF to AH bits 7, 6, 4, 2, and 0, respectively Flag Transfer SAHF (Store AH into Flags) transfers bits 7, 6, 4, 2, and 0 from AH into SF, ZF, AF, PF, and CF, respectively PUSHF (Push Flags) decrements ESP by two and then transfers the low-order word of the flags register to the word at the top of stack pointed to by ESP POPF (Pop Flags) transfers specific bits from the word at the top of stack into the low-order byte of the flag register 3.9 COPROCESSOR INTERFACE INSTRUCTIONS Coprocessor Interface ESC (Escape) is a 5-bit sequence that begins the opcodes that identify floating point numeric instructions. WAIT (Wait) is an instruction that suspends program execution until the CPU detects that the BUSY pin is inactive SEGMENT REGISTER INSTRUCTIONS MOV SegReg, Segment-Register Transfer. 82 MOV MOV..., SegReg PUSH SegReg POP SegReg JMP JMP far ; direct and indirect Direct JMP instructions that specify a target locatio outside the current code segment contain a far pointer. Indirect JMP instructions that specify a target location outside the current code segment use a 48-bit variable to specify the far pointer Far Control Transfer 82 CALL far An intersegment CALL places both the value of EIP and CS on the CALL stack. RET RET far An intersegment RET restores the values of both CS and EIP which were saved on the stack by the previous intersegment CALL instruction.

7 Data Pointer LDS transfers a pointer variable from the source operand to DS and the destination register. LES operates identically to LDS except that ES receives the segment selector rather than DS. LFS LGS LSS 3.11 MISCELLANEOUS INSTRUCTIONS 83 (Load Effective Address) transfers the offset of the source operand (rather than its Address Calculation. 83 LEA value) to the destination operand. The source operand must be a memory operand, and the destination operand must be a general register No-Operation NOP (No Operation) occupies a byte of storage but affects nothing but the instruction pointer, EIP Translate. 84 XLAT (Translate) replaced a byte in the AL register with a byte from a user-coded translation table.

complement) Multiply Unsigned: MUL (all operands are nonnegative) AX = BH * AL IMUL BH IMUL CX (DX,AX) = CX * AX Arithmetic MUL DWORD PTR [0x10]

complement) Multiply Unsigned: MUL (all operands are nonnegative) AX = BH * AL IMUL BH IMUL CX (DX,AX) = CX * AX Arithmetic MUL DWORD PTR [0x10] The following pages contain references for use during the exam: tables containing the x86 instruction set (covered so far) and condition codes. You do not need to submit these pages when you finish your