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Intel 80286, 80287 manual LAHF-load Flags into AH Register, Lahf

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THE 80286 INSTRUCTION SET

LAHF-load Flags into AH Register

OpcodeInstruction ClocksDescription

9F

LAHF

2

Load: AH = flags SF ZF xx AF xx PF xx CF

FLAGS MODIFIED

None

FLAGS UNDEFINED

None

OPERATION

The low byte of the flags word is transferred to AH. The bits, from MSB to LSB, are as follows: sign, zero, indeterminate; auxiliary carry, indeterminate, parity, indeterminate, and carry. See figure 3-5.

PROTECTED MODE EXCEPTIONS

None

REAL ADDRESS MODE EXCEPTIONS

None

8-59

Image 269

Intel 80286, 80287 manual LAHF-load Flags into AH Register, Lahf

Contents

Page Order Number Dollars ··PRICEINCall Toll Free 800 548-4725for phone orders InfefCustomer Support 80287 Programmers Reference Manual @INTELCORPORATION Organization of this Manual PrefacePage Table of Contents Extended Instruction SET Real Address ModeChapter Memory Management and Virtual Addressing Table of Contents10-3 10-110-4 10-580286/80287 Supported Data Types Flag Word ContentsDynamic Segment Relocation and Expansion of Segment Limit Code and Data Segments Assigned to a Privilege LevelReserved Exceptions and Interrupts Inter Introduction to Page Chapter Introduction to Memory Management Advanced FeaturesModes of Operation Protection Mechanisms Task ManagementOrganization of this Book Support for Operating SystemsRelated Publications Inter Base Architecture Page Memory Organization and Segmentation Chapter Base Architecture8000 r Bytes and Words in Memory Ascii ·3 /80287 Supported Data Types Base ArchitectureBase Architecture General Registers RegistersMemory Segmentation and Segment Registers Index, Pointer, and Base Registers Real Address Mode Segment Selector InterpretationInlel Inter Stack Operation BP Usage as a Stack Frame Base Pointer Implied Segment Usage by Index, Pointer, and Base Registers Status and Control Registers10. Flags Register Operands Addressing ModesMemory Addressing Modes Register and Immediate ModesSegment Selection Offset Computation EASE Architecture Segment Register Selection RulesPRog~~~D BX, 51 INPUT/OUTPUTMemory Operand AddressingModes 13. Complex Addressing Modes OUT FF,AL OUTAL,FE Interrupts and Exceptions Hierarchy of Instruction Sets Interrupt Vector Assignments Real Address Mode 80186~80188 Page Basic Instruction Set Page General-Purpose Data Movement Instructions Data Movement InstructionsPush Stack Manipulation InstructionsBasic Instruction SET Status Flags Flag Operation with the Basic Instruction SETControl Flags Hm====iPrevious Push Instructions LOW Address After Before Popa Arithmetic InstructionsBasic Instruction SET Subtraction Instructions Addition InstructionsMultiplication Instructions Boolean Operation Instructions Division InstructionsLogical Instructions Wordoprnd Shift and Rotate Instructions~-i 01, I, I aI a1,1, I, I, I a1,1,1, I aI alaiI 10 01, ,1,101, 0101,1, 01 0 10 I 1I 1I 0 1I 1 1I o I o I 1 o I 1I 1111010rrG Ll 1 1 1 l 1 Control Transfer Instructions Type Conversion and No-Operation InstructionsTest and Compare Instructions Unconditional Transfer Instructions Call Instruction Conditional Transfer Instructions JGE/JNL JG/JNLEJL/JNGE JLE/JNGSoftware-Generated Interrupts String Manipulation Instructions and Repeat Prefixes Character Translation and String InstructionsTranslate Instruction String Movement Instructions Address Manipulation Instructions Flag Control Instructions IntelFlag Transfer Instructions BINARY-CODED Decimal Arithmetic Instructions Packed BCD Adjustment InstructionsUnpacked BCD Adjustment Instructions Machine State Instructions Trusted InstructionsTrusted and Privileged Restrictions on Popf and Iret Processor Extension Instructions Input and Output InstructionsNumeric Data Processor Instructions Processor Extension Synchronization InstructionsBasic Instruction SET Data Transfer Instructions Page Extended Instruction Set Page Block 1/0 Instructions Chapter Extended Instruction SETHIGH-LEVEL Instructions Formal Definition of the Enter Instruction Extended Instruction SET Variable Access in Nested Procedures2b. Stack Frame for Procedure a 2d. Stack Frame for Procedure C at Level 3 Called from B Extended Instruction SET Page Real Address Mode Page Addressing and Segmentation Chapter Real Address ModeReal Address Mode Overlapping Segments to Save Physical Memory Real Address ModeIntr Interrupt PrioritiesNMI Reserved and Dedicated Interrupt Vectors Interrupt ProceduresESC System Initialization Processor State after ResetFlags MSW FffohReal Address Mode ·Memory Management Virtual Addressing Page Memory Management Overview Chapter Memory Management and Virtual AddressingFormat of the Segment Selector Component Virtual AddressesAddress Spaces and Task Isolation Descriptor Tables PiDPll~1 VIRTUAL-TO-PHYSICAL Address Translation PIDPLI~1LOT Descriptor Segments and Segment DescriptorsVirtual-to-Physical Address Translation Segment Address Translation Registers Memory Management Registers~,m~ =--=--=1~~ System Address Registers Memory Management and Virtual Addressing Page Protection7 Page Chapter Protection Protection Implementation Addressing Segments of a Module within a Task Descriptor Cache Registers ProtectionSeparation of Address Spaces LOT and GOT Access ChecksLJol LIT Privilege Levels and Protection Example of Using Four Privilege LevelsPrivilege Usage Segment Descriptor ~~~/do I I LJ. ITI~~ DPLData Accesses Data Access Restriction by Privilege Level Code Segment AccessPointer Privilege Stamping via Arpl NTE R Control TransfersGates 10. Gate Descriptor Format Call Gates Se!eC!0r j ,,It Niiii INTRA-LEVEL Transfers VIA Call GateCall Gate Checks INTER-LEVEL Control Transfer VIA Call Gates Protection Stack Changes Caused by Call Gates 12. Stack Contents after an Inter-Level Call Inter-Level Return Checks Tasks and State Transitions Page Task State Segments and Descriptors IntroductionTask State Segment and TSS Registers Tasks and State TransitionsTask State Segment Descriptors I01 Task SwitchingTasks and State Transitions Checks Made during a Task Switch CALL/INT Iret Task LinkingTask Gate Descriptor Task Gates~ASK Page Interrupts and Exceptions Page Interrupt Descriptor Table Definition Interrupt Descriptor TableAn eve.! eXtern8~.~~t~~pr~~~~~1 Hardware Initiated InterruptsInterrupt Gates and Trap Gates Software Initiated InterruptsTrap/Interrupt Gate Descriptors SSFROMTSS--~.~r~------~l Trap and Interrupt Gate Checks Interrupts and ExceptionsInterrupt and Gate Interactions InferDeciding Between Task, Trap, and Interrupt Gates Scheduling ConsiderationsProtection Exceptions and Reserved Vectors Processor Extension Segment Overrun Interrupt Double Fault InterruptInvalid OP-Code Interrupt Not Present Interrupt Invalid Task State Segment InterruptConditions That Invalidate the TSS Stack Fault InterruptAdditional Exceptions and Interrupts General Protection Fault InterruptIDT Single Step Interrupt InterruptSystem Control Initialization Page Descriptor Table Registers.· Chapter System Control and InitializationLocal and Global Descriptor Table Definition System Control and InitializationSystem Control Instructions MSW Bit Functions Machine Status WordIfTS=1 ESCWait 03FFH InitializationReal Address Mode 10-8 Advanced Topics Page Conforming Code Segments Virtual Memory ManagementSpecial Segment Attributes Expand-Down Segment Expand-Down Data SegmentsDynamic Segment Relocation and Expansion of Segment limit Pointer ValidationDescriptor Validation Pointer Integrity RPL and the Trojan Horse ProblemMultiprocessor Considerations NPX Context SwitchingAdvanced Topics Example of NPX Context SwitchingShutdown Page Appendix System Initialization Page Appendix a System Initialization System Initialization System .INITIALIZATION System Initialization Ax,.x Intel· Mov!w MovSiW AX,cl Page Appendix 80286 Instruction Set Page Appendix B 80286 Instruction SET Figure B-1. In Instruction Byte Format 80286 Instruction SETREG = Rb = Rw =Mod=OO Mod=01 Mod=10 Mod=11 BX + D8 SI +Figure B-2 Ir Instruction Byte Format 80286 U\lSTRUCTION SETInstruction Flags Modified ClocksDescription Real Address Mode Exceptions Protected Mode ExceptionsError Codes Flags Undefined#NM #UD#DF #MP#MP 9 Math Unit Protection Fault No Error Code #GP 13 General Protection Selector or Zero Error Code#MF 16 Math Fault No Error Code #NP 11 Not Present Selector Error Code #NM 7 No Math Unit Available No Error Code#TS 10 Invalid Task State Segment Selector Error Code #SS 12 Stack Fault Selector or Zero Error CodeSwitchtasks #UD 6 Undefined Opcode No Error CodePrivilege Level and Task Switching on 80286 Instruction SET 80286 Instruction SET AAA Ascii Adjust AL After Addition AAO AAD Ascii Adjust AX Before DivisionAAM D4 OAAAS AAS-ASCII Adjust AL After SubtractionADD ADC/ ADD-Integer AdditionADC AND-Logical ARPL- Adjust RPL Field of Selector Bound rw,md noj=13 BOUND-Check Array Index Against BoundsFlags Undefined Flags ModifiedOperation CallCall Conforming Code Segment Call FARCall Nonconforming Code Segment Call to Call Gate80286 Instruction SET Call Gate to More Privilege Protected Mode ExceptionsCall Gate to Same Privilege Call Task GateInterrupt l3 for a word operand at offset Offffh C8W Caw-Convert Byte into WordCLC CLC-Clear Carry FlagCLO CLD-Clear Direction FlagReal Address Mode Exceptions Protected Mode ExceptionsEll-Clear Interrupt Flag 80286·INSTRUCTION SETOpcode Instruction ClocksDescription CLTS-Clear Task Switched FlagCMC CMC-Complement Carry FlagCMP CMP-Compare Two OperandsCmpsw CMPS8CWD CWO-Convert Word to DoublewordDAA DAA-Decimal Adjust AL After AdditionDAS-Decimal Adjust AL After Subtraction Opcode Structlon Clocks Description DEC-Decrement byDIVew DIV -Unsigned DivideDIVeb BP= Frameptr ENTER-Make Stack Frame for Procedure Parameters80286 Instruction SET Protected Mode Exceptions HLT-Halt IDIV-Signed Divide Opcode Instruction Clocks Description Imul eb IMUL-Signed Multiply21,mem=24 Signed multiply rw = 21,mem=24 Signed multiply rw = EA word X imm. byteIN-Input from Port Mem=7 Increment EA word by INCINS INS/INSB/INSW-Input from Port to StringInsb InswINT3 INT IINTO-Call to Interrupt ProcedureInterrupt to Same Privilege Level InterruptInterrupt to Inner Privilege #GP, #NP, #SS, and #TS, as indicated in the list above Opcode Instruction Clock Description IRET-Interrupt ReturnIret Interrupt ReturnInterrupt Return to Same Level Interrupt Return on Stack#GP, #NP, or #88, as indicated in the above listing JBE JAEJGE JLE80286 Instruction SET JMP-Jump Jump Conforming Code Segment Jump FARJump Nonconforming Code Segment Jump to Call GateJump Task State Segment Lahf LAHF-load Flags into AH RegisterReal Address Mode Exception 14,mem=16 Load highrw= Access Rights byte, selector ewInstruction SET 02 IrLES LOS/ LES-Load Doubleword PointerLDS 80286 Instruction SET Protected Mode Exceptions Effective Address Offset LEA-loadLeave LEAVE-HighLevel Procedure ExitLgdt LGDTILIDT-Load Global/Interrupt Descriptor Table RegisterLoad m into Global Descriptor Table reg LlDTLldt ew LLDT-Load Local Descriptor Table RegisterLoad selector ew into Local Descriptor Table Register01 /6 LMSWew Mem=6 LMSW-Load Machine Status WordLock LOCK-AssertBUS Lock SignalLodsw LodsLODS8 LOOP/LOOPcond-Loop Control with CX Counter 14,mem=16 Load rw = Segment Limit, selector ew LSL-LoadSegment Limit00 /3 LTR ew 17,mem=19 LTR-Load Task RegisterMem=3 Move byte register into EA byte Opcode Instruction Clocks DescriptionMem=3 Move word register into EA word Mem=5 Move EA byte into byte registerInterrupt 13 for a word operand at offset Offffh Movs MOVS/MOVSB/MOVSW-Move Data from String to StringMOVS8 MovswMUL-Unsigned Multiplication of AL or AX NEG ew NEG-TwosComplement NegationNEG eb NOP-No Operation Not NOT-OnesComplement NegationOR- Logical Inclusive or Output byte AL to port number OX OUT OX,ALOUT OX,AX Output word AX to port number OXOutsw OutsOutsb POP SS POPInter Popa FlAGS UndefinedPopf POPF-Pop from Stack into the Flags RegisterPush PUSH-Push a Word onto the StackPush CS Push SSPUSHA-Push All General Registers Pushf PUSHF-Push Flags Register onto the StackPush flag~ register RCR RCLROL RORInterrupt 13 for a word operand at offset Offffh REP Insb REP INSREP Insw REP Movs80286 Instruction SET RET RET -Return from ProcedureReturn to Outer Privilege Level Return to Same LevelSahf Sahf -Store AH into FlagsSHR SALSAR Interrupt 13 for a word operand at offset Offffh SBB SBB-Integer Subtraction With BorrowSCAS/SCASB/SCASW-Compare String Data 101 Sgdt /SIDT-Store Global/Interrupt Descriptor Table RegisterSLOT-Store Local Descriptor Table Register 103 Smsw -Store Machine Status Word104 STe-SetCarry FlagSTO STOSetDirection FlagSTI STI-Set Interrupt Enable FlagStosw Stoss108 STR-Store Task Register00 /1 STR ew Mem=3 SUB SUB-Integer SubtractionTest TEST-Logical Compare14,mem=16 Set ZF=1 if seg. can be read, selector ew VERR,VERW-Verifya Segment for Reading or Writing14,mem=16 111112 Wait WAIT-Wait Until Busy Pin Is Inactive HighXchg XCHG- Exchange Memory/Register with RegisterXlat mb Set AL to memory byte Osbx + unsigned Xlat -Table Look-up TranslationXlatb 115XOR XOR-Logical Exclusive orAppendix 8086/8088 Compatibility Considerations Page Table C-1. New 80286 Interrupts Software Compatibility ConsiderationsPushbp MOVBP,SP XCHGBP,BP Hardware Compatibility Considerations Page 80286/80386 Software Page 80286/80386 Softvvare 80286/80386 Software Compatibility Considerations Index-1 IndexIndex-2 Index-3 Index-4 LODS/LODSB/LODSW, 3-24, B-69Index-5 Index-6 Numeric Processor Extension NPX Page 80286 Microsystem AN Introduction toRelated Publications Organization of This ManualUnnormals-Descendents of Denormal Operands Chapter Overview of Numeric ProcessingChapter SYSTEM-LEVEL Numeric Programming 80287 Glossary of 80287 and FLOATING-POINT Terminology IndexStorage Allocation Directives TablesOverview of Numeric Processing Page Performance Introduction to the 80287 Numeric Processor ExtensionFxam StackO assumed Examine Overview of Numeric Processing± Vb2 4ac ApplicationsUpgradability PASCAL-286 FORTRAN-286 Programming InterfaceNumeric Data Types Hardware Interface~r=~=~ NPX Register Stack Numeric Processor Architecture80287 Register Set NPX Status WordStatus Word Control WordInfinity, positive Inter Tag Word Format Number System Computation FundamentalsNumber System Data Types and FormatsData Formats Binary Integers Rounding Control ·6. Rounding Modes Precision ControlSpecial Numeric Values Special Computational SituationsNonnormal Real Numbers Overview of Numeric Processing Denormalization ProcessUnnormals-Descendents of Denormal Operands Fsqrt FrndintFIST, FISTP, Fbstp FLDInfinity Fbstp FIST, Fistp FLD, FBLD1 FILD2 FST,FSTPFprem Fsqrt+co Ftst FrndintFxtract Smallest LargestZero Smallest ......1 ---- 15 bits-----l..~1U U ZeroU U2 Bits 16. Temporary Real Encodings Sign Biased Exponent Class NaNsSignificand· NormalsZero Divisor 16. Temporary Real Encodings ContdInvalid Operation Overview of Numeric Processing Denormalized Operand 17. Exception Conditions and Masked Responses Masked response to overflow exception earlier 17. Exception Conditions and Masked Responses Contd11. Arithmetic Example Using Infinity Software Exception Handling Programming Numeric Applications Page Numeric Operands 80287 NPX Instruction SETCompatibility with the 8087 NPX Data Transfer Instructions FAD D destination, sourceProgramming Numeric Applications Arithmetic Instructions Arithmetic Instructions Fsub FaddFmulp Fdiv AzimuthFsubrp / /destination/source Fprem Condition Code Interpretation after Fprem Fcom / /source Programming Numeric Applications FabsComparison Instructions Condition Code Interpretation after FcomFxam FcomppSTO 1r FptanF2XM1 FpatanFYL2X FYL2XP1Constant Instructions Processor Control Instructions Finitifninit Fstsw AX/FNSTSW AX FSAVE/FRSTOR Memory Layout Fstenvifldenv Memory Layout Ffree destination Instruction Execution Time 12. Key to Operand TypesProgramming Numeric Applications 13. Execution Penalties Instruction Length ·14. Instruction Set Reference Data 14. Instruction Set Reference Data Contd Fdiv Programming Numeric Applications FdecstpFdivp FdivrFiadd DISTANCE..TRAVELLED Fiadd Pulsecount SI Ffree ST1Ficom TOOL.NPASSES Ficom BP+4.PARMCOUNTFild Standoff DI Fidivr FrequencyFild RESPONSE.COUNT Fimul BearingFist BP.FACTOREDPULSES Fist OBS.COUNTSIFistp BX.ALPHACOUNT SI Fistp CorrectedtimeFLO 8AVEREADING FLD Reading 81.PRE88UREFldcw Controlword FLDLG2FLOL2T FLOL2EFlopi FlozFpatan Fmul SpeedfactorFmulp ST1,ST Fptan ·14. Instruction Set Reference Data ContdFrstor BP Fsave BPFST Correlation FST ST3FST Meanreading Fstcw SavecontrolFstp ST2 Fstp BX.ADJUSTEDRPMFstp Totaldosage Fstp Regsave SIFsubr Vectorsi Fsubr ST,ST1Fsubr BX.INDEX Fsubrp ST1,STFYL2XP1 Fxch ST2FYL2X High-Level Languages Programming Facilities15. PLlM-286 Built-In Procedures Interpretation Data Types ASM286BIT String Shorti Nteger OFFFFFF82H HEX Must Start Status Word Record Definition TR E QFiaooalpha FOIVRALPHA.BETA 17. Addressing Mode ExamplesFsub Alpha SI Filo BP.BETASample PL/M-286 Program It *itConcurrent Processing with Emulation·7. Sample ASM286 Program Intel Programming Numeric ApplicationsSample ASM286 Program Contd Instruction Synchronization Managing ConcurrencyData Synchronization Synchronizing References to Shared Data Error SynchronizationMOV Fsgrt System-Level Numeric Programming Page Processor Extension Data Channel Real-Address Mode and Protected Virtual-Address ModeArchitecture Processor Initialization and Control Dedicated and Reserved 1/0 LocationsSystem Initialization Recognizing. the 80287 NPXSoftware Routine to Recognize SYSTEM-LEVEL Numeric ProgrammingConfiguring the Numerics Environment NPX Processor State Following Initialization InitializingHandling Numeric Processing Exceptions InterSimultaneous Exception Response Precedence of NPX Exceptions Numeric Programming Examples Page Chapter Numeric Programming Examples XAM Jump Table for Examine RoutineConditional Branching for Fxam Contd Numeric Programming ExamplesProc MOV Byte PTR IBP-121, OH Fldenv Fnsave BP-941 FLOATING-POINT to Ascii Conversion Examples It116 Ebde DoeF \ii.t 4BB Lei Function. Partitioning Description of Operation Exception ConsiderationsSpecial Instructions Scaling the Value Trigonometric Calculation Examples Output FormatNumeric Programming Examples Calculating Trigonometric Functions207 Arg 0o,3 Coce 4676 Page Machine Instruction Encoding and Decoding Page REG OP-A MOD OP-S Displacement Format OP-AMODTable A·2. Machine Instruction Decodin.9 Guide Machine Instruction Encoding and DecodingModoo Machine Instruction Encoding and DecodingMOD01 MOD10Table A-2. Machine Instruction Decoding Guide Contd Oreg 1REGFstswax XXXPage Appendix Compatibility Between NPX Page 80287 NPX Appendix B Compatibility BetweenNI NIT Appendixc· Page Appendix C Implementing the Ieee P754 Standard Additional Software to Meet the Standard Implementing the Ieee P754 Standard Page Glossary of 80287 and Floating-Point Terminology Page Glossary-1 Glossary FLOATING-POINT TerminologyInter Glossary of 80287 and FLOATING-POINT Terminology Glossary-3 Glossary of 80287 and FLOATING-POINT TerminologyGlossary-4 Glossary of 80287 and FLOATING-POINT Terminology Page Index Index-2 NO-WAIT Form Index-4 Inter Inter IntJ European Sales Offices