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![]() Intel and compatable CPU's Programming Information ![]() |
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Intel SSE MMX2 KNI documentation AMD 64 Bit & Opteron resource on this site Intel Itanium 64 Bit processor Intel 80386 Reference Programmer's Manual Our Partners: |
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LEA -- Load Effective AddressOpcode Instruction Clocks Description 8D /r LEA r16,m 2 Store effective address for m in register r16 8D /r LEA r32,m 2 Store effective address for m in register r32 8D /r LEA r16,m 2 Store effective address for m in register r16 8D /r LEA r32,m 2 Store effective address for m in register r32 OperationIF OperandSize = 16 AND AddressSize = 16 THEN r16 := Addr(m); ELSE IF OperandSize = 16 AND AddressSize = 32 THEN r16 := Truncate_to_16bits(Addr(m)); (* 32-bit address *) ELSE IF OperandSize = 32 AND AddressSize = 16 THEN r32 := Truncate_to_16bits(Addr(m)); ELSE IF OperandSize = 32 AND AddressSize = 32 THEN r32 := Addr(m); FI; FI; FI; FI; DescriptionLEA calculates the effective address (offset part) and stores it in the specified register. The operand-size attribute of the instruction (represented by OperandSize in the algorithm under "Operation" above) is determined by the chosen register. The address-size attribute (represented by AddressSize) is determined by the USE attribute of the segment containing the second operand. The address-size and operand-size attributes affect the action performed by LEA, as follows:Operand Size Address Size Action Performed 16 16 16-bit effective address is calculated and stored in requested 16-bit register destination. 16 32 32-bit effective address is calculated. The lower 16 bits of the address are stored in the requested 16-bit register destination. 32 16 16-bit effective address is calculated. The 16-bit address is zero-extended and stored in the requested 32-bit register destination. 32 32 32-bit effective address is calculated and stored in the requested 32-bit register destination. Flags AffectedNoneProtected Mode Exceptions#UD if the second operand is a registerReal Address Mode ExceptionsInterrupt 6 if the second operand is a registerVirtual 8086 Mode ExceptionsSame exceptions as in Real Address Mode
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Chapter 17 -- 80386 Instruction Set |