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ARM r1p3, R4F manual Internal exclusive monitor

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Level One Memory System

8.6Internal exclusive monitor

The processor L1 memory system has an internal exclusive monitor. This is a two state, open and exclusive, state machine that manages load/store exclusive (LDREXB, LDREXH, LDREX, LDREXD, STREXB, STREXH, STREX and STREXD) accesses and clear exclusive (CLREX) instructions. You can use these instructions, operating in the L1 memory system, to construct semaphores and ensure synchronization between different processes. By adding an external exclusive monitor, you can also use these instructions in the L2 memory system to construct semaphores and ensure synchronization between different processors. See the ARM Architecture Reference Manual for more information about how these instructions work.

When a load-exclusive access is performed, the internal exclusive monitor moves to the exclusive state. It moves back to the open state when a store exclusive access or clear exclusive instruction is performed. The internal exclusive monitor holds exclusivity state for the Cortex-R4 processor only. It does not record the address of the memory that a load-exclusive access was performed to. Any store exclusive access performed when the state is open fails. If the state is exclusive, the access passes if it is to non-shared memory but, if it is to shared memory, the access must be performed as an exclusive using the L2 memory interface. Whether the shared store-exclusive access passes or fails depends on the state of an external exclusive monitor which can track accesses made by other processors in the system.

ARM DDI 0363E	Copyright © 2009 ARM Limited. All rights reserved.	8-34
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ARM r1p3, R4F manual Internal exclusive monitor

Contents

Cortex-R4 and Cortex-R4F Copyright 2009 ARM Limited. All rights reserved Cortex-R4 and Cortex-R4FTechnical Reference Manual Cortex-R4 and Cortex-R4F Technical Reference Manual Chapter IntroductionChapter Processor Initialization, Resets, and Clocking Chapter AC Characteristics Appendix B ECC Schemes List of Tables Adfsr and Aifsr bit functions Dirty register format, with ECC 11-12 Example interlocks 14-11 Table A-18 FPU signals Table C-1 List of Figures Cache operations C7 format for Set and Way Vector Catch Register format 11-20 Preface Feedback onProduct revision status Using this bookAbout this book Identifies the major revision of the productConventions TypographicalTiming diagrams SignalsARM publications Further readingThis section lists publications by ARM and by third parties Other publicationsFeedback on this product FeedbackARM welcomes feedback on this product and its documentation Feedback on this bookIntroduction About the processor About the architecture Debug on Components of the processorThis section describes the main components of the processor System control coprocessor on Interrupt handling onLoad/store unit Data Processing UnitFloating Point Unit Prefetch unitTCM interfaces Instruction and data cachesMemory Protection Unit AXI master interface Error correction and detection5 L2 AXI interfaces AXI slave interfaceETM interface DebugSystem performance monitoring Real-time debug facilitiesVIC port System control coprocessorInterrupt handling Low interrupt latencyReturn from exception using data from the stack ChangesAPB Debug interface ETM interface Test interface Processor has the following interfaces for external accessExternal interfaces of the processor APB Debug interfaceStandby mode Power managementRun mode Shutdown modeAtcm Configurable optionsConfigurable options FPU includeda BtcmVFP MPUB0TCMPCEN Configurable options at reset Feature Options RegisterAtcmpcen B1TCMPCENB1TCMECEN AtcmecenB0TCMECEN AtcmrmwInstruction decode Execution pipeline stagesNames of the pipeline stages and their functions are Execute stages First stage of data memory accessIss Write-back of data from the execution pipelinesRedundant core comparison Test features Design flow Product documentation, design flow, and architectureDocumentation Software configuration Build configurationConfiguration inputs Architectural informationAdvanced Microcontroller Bus Architecture protocol Product revision information Processor identificationVariant field, Debug ID Register Variant field, Main ID RegisterRevision field, Main ID Register Revision field, Debug ID RegisterProgram status registers on Programmer’s ModelRegisters on Exceptions onAbout the programmer’s model ARM state Switching stateInstruction set states Thumb stateOperating modes Data types Byte-invariant big-endian format Memory formatsByte-invariantbig-endian format Little-endian format Little-endian formatRegisters Register setRegister mode identifiers Mode Mode identifier General registers and program counter Program status registers N, Z, C, and V bitsQ bit IT bitsGE bits J bitDNM bits I and F bits E bitA bit Non-maskable fast interrupts onM bits PSR mode bit valuesM40 Mode Visible state registers Thumb Modification of PSR bits by MSR instructionsARM DDI 0363E Exception entry and exit summary Reset on Interrupts on Aborts onExceptions Exception entry and exit summaryTaking an exception Leaving an exceptionInterrupt request ResetInterrupts Non-maskable fast interrupts Fast interrupt requestProgram status registers on Non-maskable fast interrupts Interrupt entry flowchart Interrupt controllerInterrupt entry sequence Data aborts AbortsPrefetch aborts Precise abortsImprecise aborts Aborts in Strongly Ordered and Device memoryAbort handler Supervisor call instructionUndefined instruction Breakpoint instructionException vectors Acceleration of execution environments Unaligned and mixed-endian data access support Architecture Reference ManualBig-endian instruction support Reset modes on Processor Initialization, Resets, and ClockingResets on Initialization on1 MPU InitializationCaches on TCM on 2 CRSPreloading TCMs Caches5 TCM Preloading TCMs with parity or ECC DMA into TCMWrite to TCM directly from debugger Using TCMs from reset PRESETDBGn ResetsNRESET NSYSPORESETReset modes Power-on resetHalt operation Processor resetNormal operation AXI interface clocking ClockingAXI interface clocking Clock gating Clock gatingSystem Control Coprocessor About the system control coprocessor System control coprocessor functional groupsFcse PID System control coprocessor register functionsFunction Register/operation Reference to description TCM control TCM Status System control and configurationConfiguration Region System performance Performance monitoringMPU control and configuration Cache control and configurationTCM control and configuration System performance monitorSystem validation System performance monitor registersARM DDI 0363E RAZ System control coprocessor registersRegister allocation Control Undefined MPU Memory Region Read/write Enable Undefined MPU Region Access Read/writeUndefined MPU Region Size Read/write NumberARM DDI 0363E Count Undefined Undefined C3-c11 C12 Performance Monitor Read/writeEvent Select Read/write Unpredictable Performance Monitor RAZ,ignore C14 User Enable Read/writeUndefined C1-c15 C12 C0-c15 C13 Writes Context ID Read/write2 c0, Main ID Register 7shows the arrangement of bits in the registerBits Field Function 3 c0, Cache Type RegisterMain ID Register bit functions Cache Type Register bit functions Bits Field Function To access the Cache Type Register, read CP15 with4 c0, TCM Type Register TCM Type Register bit functions Bits Field Function5 c0, MPU Type Register To access the TCM Type Register, read CP15 withTo access the MPU Type Register, read CP15 with TCM Type Register bit functions6 c0, Multiprocessor ID Register Processor Feature RegistersC0, Processor Feature Register 0, PFR0 Processor Feature Register 0 bit functions To access the Processor Feature Register 0 read CP15 withC0, Processor Feature Register 1, PFR1 Processor Feature Register 1 bit functionsDebug Feature Register 0 bit functions To access the Processor Feature Register 1 read CP15 with8 c0, Debug Feature Register 3124 ReservedMemory Model Feature Registers To access the Debug Feature Register 0 read CP15 with9 c0, Auxiliary Feature Register C0, Memory Model Feature Register 0, MMFR0C0, Memory Model Feature Register 1, MMFR1 10 Memory Model Feature Register 0 bit functions16 Memory Model Feature Register 1 format 11 Memory Model Feature Register 1 bit functionsDMB C0, Memory Model Feature Register 2, MMFR2WFI 3112 Reserved C0, Memory Model Feature Register 3, MMFR313 Memory Model Feature Register 3 bit functions 14 Instruction Set Attributes Register 0 bit functions Instruction Set Attributes RegistersC0, Instruction Set Attributes Register 0, ISAR0 C0, Instruction Set Attributes Register 1, ISAR1 20 Instruction Set Attributes Register 1 formatIndicates support for if then instructions C0, Instruction Set Attributes Register 2, ISAR2ITE Indicates support for PSR instructions 16 Instruction Set Attributes Register 2 bit functionsPSR Thumb instruction sets C0, Instruction Set Attributes Register 3, ISAR317 Instruction Set Attributes Register 3 bit functions C0, Instruction Set Attributes Register 4, ISAR4 23 Instruction Set Attributes Register 4 format18 Instruction Set Attributes Register 4 bit functions C0, Instruction Set Attributes Registers12 c0, Current Cache Size Identification Register 4KB 8KB13 c0, Current Cache Level ID Register 3130 Reserved14 c0, Cache Size Selection Register 15 c1, System Control RegisterTRE 23 System Control Register bit functionsAFE Nmfi= data caching enabled Enables L1 data cache= data caching disabled. This is the reset value = strict alignment fault checking enabled24 Auxiliary Control Register bit functions Auxiliary Control RegistersC1, Auxiliary Control Register Dilsm AxiscenAxiscuen DeolpDlfo RsdisDbwr DnchC15, Secondary Auxiliary Control Register 25 Secondary Auxiliary Control Register bit functions OFC DoofmacsIXC UFCPrimary input RMWENRAM0 defines the reset value 17 c1, Coprocessor Access RegisterPrimary input RMWENRAM1 defines the reset value AtcmeccAll other encodings for these FSR bits are Reserved Fault Status and Address RegistersC5, Data Fault Status Register To use the Dfsr read or write CP15 with C5, Instruction Fault Status Register28 Data Fault Status Register bit functions There are two auxiliary fault status registers To access the Ifsr read or write CP15 withC5, Auxiliary Fault Status Registers 29 Instruction Fault Status Register bit functions= Atcm C6, Data Fault Address Register30 Adfsr and Aifsr bit functions = BtcmC6, Instruction Fault Address Register 19 c6, MPU memory region programming registersC6, MPU Region Size and Enable Registers C6, MPU Region Base Address Registers32 Region Size Register bit functions C6, MPU Region Access Control Registers158 Sub-region disable 33 MPU Region Access Control Register bit functions TEXUNP 34 Access data permission bit encodingC6, MPU Memory Region Number Register 35 MPU Memory Region Number Register bit functionsPoint of Unification PoU Cache operationsPoint of Coherency PoC Invalidate and clean operations Set and Way format36 Functional bits of c7 for Set and Way 37shows the cache sizes and the resultant bit range for SetAddress format 37 Widths of the set field for L1 cache sizes Size Set21 c9, Btcm Region Register Data Synchronization Barrier operationData Memory Barrier operation 38 Functional bits of c7 for address format Bits Field39 Btcm Region Register bit functions To access the Btcm Region Register, read or write CP15 with22 c9, Atcm Region Register 24 c11, Slave Port Control Register To access the Atcm Region Register, read or write CP15 with23 c9, TCM Selection Register 40 Atcm Region Register bit functions312 Reserved 25 c13, Fcse PID Register26 c13, Context ID Register RAZ/UNP27 c13, Thread and Process ID Registers Ccnt overflow IRQ request C15, nVAL IRQ Enable Set RegisterValidation Registers C15, nVAL FIQ Enable Set Register Ccnt overflow FIQ requestCcnt overflow reset request C15, nVAL Reset Enable Set RegisterC15, nVAL Debug Request Enable Set Register C15, nVAL IRQ Enable Clear Register Ccnt overflow debug requestC15, nVAL FIQ Enable Clear Register 48 nVAL IRQ Enable Clear Register formatC15, nVAL Reset Enable Clear Register 303 Reserved UNP or SbzpC15, nVAL Debug Request Enable Clear Register 51 nVAL Debug Request Enable Clear Register format318 Reserved C15, nVAL Cache Size Override Register50 nVAL Cache Size Override Register B0000 4kB B0001 8kB B0011 16kB B0111 32kB B1111 64kBCorrectable Fault Location Register 53 Correctable Fault Location Register cache52 Correctable Fault Location Register cache C15, Build Options 1 Register To access the Build Options 1 Register, write CP15 withBuild Options Registers C15, Build Options 2 RegisterNodcache 55 Build Options 2 RegisterNoicache AtcmesNofpu BtcmesNoie NompuDcachees To access the Build Options 2 Register, write CP15 withNoharderrorcach AxibusparityPrefetch Unit About the prefetch unit Branch prediction Disabling program flow predictionIncorrect predictions and correction Configuring the branch predictorBranch predictor Return stack Events and Performance Monitor Event bus interface bit functions Bit position Update ValueAbout the events EventETMEXTOUT0 ETMEXTOUT1But with different attributes Dual issue case a branch Non-cacheable access on AXI master busInstruction cache access Dual issue case B1, B2, F2 load/store, F2DTCM correctable ECC error reported by load/store unit Yes TCM correctable ECC error reported by prefetch unit YesAbout the PMU 1 c9, Performance Monitor Control Register Performance monitoring registersPerformance monitoring registers are described 2shows how the bit values correspond with the Pmnc Register2 c9, Count Enable Set Register Pmnc Register bit functionsCntens Register bit functions Bits Field Function To access the Cntens Register, read or write CP15 with3 c9, Count Enable Clear Register 4 c9, Overflow Flag Status Register To access the Cntenc Register, read or write CP15 withCycle counter enable clear Cntenc Register bit functions Bits Field Function5 c9, Software Increment Register To access the Flag Register, read or write CP15 with5shows how the bit values correspond with the Flag Register Swincr Register bit functions Bits Field Function To access the Swincr Register, read or write CP15 with6 c9, Performance Counter Selection Register 313 Reserved RAZ on reads, Sbzp on writes Increment CounterSEL 7 c9, Cycle Count Register8 c9, Event Selection Register To access the EVTSELx Register, read or write CP15 with EVTSELx Register bit functionsUseren Register bit functions 10 c9, User Enable Register9 c9, Performance Monitor Count Registers 10 Intens Register bit functions Bits Field Function 11 c9, Interrupt Enable Set RegisterCcnt overflow interrupt enable 11 Intenc Register bit functions Bits Field Function 12 c9, Interrupt Enable Clear RegisterCcnt overflow interrupt enable bit To access the Intenc Register, read or write CP15 with Event bus interface Use of the event bus and countersMemory Protection Unit MPU faults onMPU software-accessible registers on True Default memory mapAbout the MPU Region size Memory regionsRegion base address SubregionsOverlapping regions Region access permissionsRegion attributes RegionExample of using regions that overlap Example of using subregionsBackground regions TCM regionsUsing memory types Memory typesARM DDI 0363E Region attributes TEX20, C, and B encodings Description Memory Type Shareable?Cacheable memory policies 1BBFollowing code is an example of disabling the MPU On page 7-2shows the default memory mapMPU interaction with memory system Background fault MPU faultsBackground fault Permission fault Alignment fault Permission faultMPU software-accessible registers On page 4-5shows the CP15 registers that control the MPULevel One Memory System About the L1 memory system L1 memory system block diagram Parity About the error detection and correction schemesParity Bit ECC on Bit ECC Error checking and correctionHard errors Read-Modify-WriteCorrect-and-retry Error correctionCorrect inline Classes of fault that can occur are Fault handlingFaults MPU faultsTCM external faults External faultsCache and TCM parity and ECC errors Precise and imprecise aborts Fault status informationDebug events Abort exceptionsUsage models Precise abort exceptionsImprecise abort exceptions AXI Correctable errorsTypes of aborts Conditions Source Precise Fatal ARM DDI 0363E About the TCMs TCM attributes and permissionsHandling TCM parity errors on Handling TCM ECC errors on Atcm and Btcm configurationTCM internal error detection and correction TCM arbitration Handling TCM parity errorsHandling TCM ECC errors TCM port protocol External TCM errorsTCM initialization AXI slave interfaces for TCMs About the caches Store bufferStore buffer behavior Cache maintenance operationsStore buffer merging Store buffer drainingCache error detection and correction Error build optionsCache parity error behavior Value Behavior Address decoder faultsHandling cache parity errors Handling cache ECC errors Cache ECC error behavior Value BehaviorErrors on data cache write Errors on instruction cache readErrors on data cache read Errors on evictionsInvalidate all instruction cache Clean data cache by set/way Dirty RAM on Data RAM on Cache RAM organizationTag RAM Tag RAMCache sizes and tag RAM organization Tag RAM organization Dirty RAMData RAM Organization of a dirty RAM lineNonsequential read operation performed with one RAM access Data RAM sizes without parity or ECC implemented 13 Data cache RAM bits, with parity Description Following code is an example of enabling caches Cache interaction with memory systemDisabling or enabling all of the caches 15 Data cache data RAM sizes with ECC Cache size Data RAMsDisabling or enabling data cache Disabling or enabling error checkingDisabling or enabling instruction cache MCR p15 R0, c1 Write System Control Register Internal exclusive monitor Memory types and L1 memory system behavior Instruction-cache error events Error detection eventsTCM error events Data-cache error eventsARM DDI 0363E Level Two Interface About the L2 interface Attribute Value Comments AXI master interface1shows the AXI master interface attributes Outstanding write accesses with the same ID Identifiers for AXI bus accessesOutstanding write/read access on different IDs Write responseArcachem and Awcachem encodings Encoding a Meaning Eviction bufferMemory attributes Aruserm and Awuserm encodingsMemory system implications for AXI accesses Linefills on AXI master interface transfersStrongly Ordered and Device transactions on Non-cacheable Ldrb Restrictions on AXI transfersStrongly Ordered and Device transactions Address20LDR or LDM that transfers one register Ldrh from Strongly Ordered or Device memory Address30LDM that transfers five registers LDM5, Strongly Ordered or Device memory Address40Strb to Strongly Ordered or Device memory Address40 Strh to Strongly Ordered or Device memory Address20First Wstrbm STR or STM of one registerSTM of seven registers Non-cacheable reads LinefillsCache line write-back eviction 14 Ldrh from Non-cacheable Normal memory Address20 15 LDR or LDM1 from Non-cacheable Normal memory Address20Non-cacheable or write-through writes AXI transaction splitting Normal write merging 20 AXI transaction splitting, data in two cache linesExample 9-1 Write merging ARM DDI 0363E AXI slave interface AXI slave interface for cache RAMsAXI slave control TCM parity and ECC supportCache parity and ECC support AXI slave characteristics 25 AXI slave interface attributesEnabling or disabling AXI slave accesses 26 RAM region decode AxUSERS bit One-hot RAM select Accessing RAMs using the AXI slave interfaceTCM RAM access on Cache RAM access on 27 TCM chip-select decode Btcm ports TCM RAM accessARADDRSMSB, see Table RAM selectedThis section contains the following Cache RAM accessMemory map when accessing the cache RAMs 31 Cache data RAM bank/address decode Inputs ARADDRS1815 Data RAM access0010 Bank 0100 1000 0001 Bank 0010 0100 100034 Data format, instruction cache, with ECC 35 Data format, data cache, with ECC Data bit DescriptionTag RAM access ARM DDI 0363E Dirty RAM access 43 Dirty register format, with ECC Data bit DescriptionOther examples of accessing cache RAMs ARADDRS1815 = 4b1111Power Control About power control on Power management onAbout power control Dormant mode Run modeStandby mode Shutdown modeCommunication to the Power Management Controller Debug Debug state on Cache debug onDebug host Debug systemsDebug host Protocol converter Debug target Protocol converterMonitor debug-mode debugging About the debug unitHalting debug-mode debugging Programming the debug unitAll other state information associated with the debug unit Coprocessor registers 11.3.2 CP14 access permissionsDebug register interface Coprocessor registers summaryInstruction Mnemonic Description Offset Register Access Mnemonic Description Hex NumberMemory-mapped registers Debug memory-mapped registersMemory addresses for breakpoints and watchpoints APB port access permissions Power domainsEffects of resets on debug registers Privilege of memory access permissionOther Debug registers External debug interface access permissions RegistersLock Other registers6shows the CP14 debug register map Accessing debug registersDebug register descriptions 11.4.2 CP14 c0, Debug ID RegisterBRP Debug ID Register functionsWRP To use the Debug ROM Address Register, read CP14 c0 with To use the Debug ID Register, read CP14 c0 with11.4.3 CP14 c0, Debug ROM Address Register 11.4.4 CP14 c0, Debug Self Address Offset RegisterDebug Self Address Offset Register format Debug Self Address Offset Register functions11.4.5 CP14 c1, Debug Status and Control Register 10 Debug Status and Control Register functionsFlag is set to 1 on entry to debug state ARM Execute ARM instruction enable bit= disabled, this is the reset value DTR access mode MOEData Transfer Register Vector Catch Register Watchpoint Fault Address Register12 Watchpoint Fault Address Register functions Reserved RAZSVC Instruction Transfer Register Bits Field Reset Description ValueDebug State Cache Control Register 14 Debug State Cache Control Register functions315 Reserved Debug Run Control Register15 Debug Run Control Register functions Breakpoint Value Registers Breakpoint Control Registers17 Breakpoint Control Registers functions 18 Meaning of BVR bits +0 is accessedCorresponding instruction address breakpoint BVR2220 Meaning19 Watchpoint Value Registers functions Bits Description Watchpoint Value RegistersWatchpoint Control Registers 11 Watchpoint Control Registers format 20 Watchpoint Control Registers functionsAccessed Operating System Lock Status RegisterAuthentication Status Register 21 OS Lock Status Register functions= Dbgnopwrdwn is LOW. This is the reset value Device Power-down and Reset Control RegisterDevice Power-down and Reset Status Register 23 Prcr functions15 Prsr format 24 Prsr functionsManagement registers Processor ID Registers27 Claim Tag Set Register functions Bits Field Function Claim RegistersClaim Tag Set Register Claim Tag Clear Register Lock Access Register318 Reserved RAZ or Sbzp Claim tag clear Reset value is Lock Status Register30 Device Type Register functions Device Type RegisterDebug Identification Registers 33 Peripheral ID Register 0 functions 32 Fields in the Peripheral Identification RegistersField Size Description Bits Value Description36 Peripheral ID Register 3 functions 34 Peripheral ID Register 1 functions35 Peripheral ID Register 2 functions 37 Peripheral ID Register 4 functions1021 1020Component Identification Register 1022Debug events Software debug eventDebug event priority Halting debug eventBehavior of the processor on debug events Watchpoint debug eventsDebug exception Effect of debug exceptions on CP15 registers and Wfar 40shows the values in the link register after exceptionsFollowing sections describe Four CP15 registers that record abort information areAvoiding unrecoverable states Entering debug state Debug statePrivilege on 41 Read PC value after debug state entryBehavior of the PC and Cpsr in debug state 41 Read PC value after debug state entry Debug eventWriting to the Cpsr in debug state Accessing registers and memoryExecuting instructions in debug state PrivilegeEffects of debug events on processor registers Coprocessor instructionsEffect of debug state on non-invasive debug Exceptions in debug stateImprecise Data Aborts on entry and exit from debug state Precise Data abortImprecise Data Abort Leaving debug stateSets the DSCR1 core restarted flag to Cache pollution in debug state Cache debugThis section describes cache debug. It consists Cache coherency in debug stateThis section describes the miscellaneous debug signals APB signalsMiscellaneous debug signals External debug interface42 Authentication signal restrictions Dbgen a Authentication signalsChanging the authentication signals Non-invasive debug permittedIssue an Instruction Synchronization Barrier ISB instruction Using the debug functionality Example 11-1 Executing an ARM instruction through the ITRRules for accessing the DCC Debug communications channelExample 11-5shows the code for host-to-target data transfer Software access to the DCCDebugger access to the DCC Example 11-4 Target to host data transfer host endProgramming simple breakpoints and the byte address select Programming breakpoints and watchpointsThis section describes the following operations Example 11-6 Polling the DCC host endSetting a simple aligned watchpoint Example 11-7 Setting a simple breakpointSetting a simple unaligned watchpoint Example 11-8 Setting a simple aligned watchpointSingle-stepping Example 11-9 Setting a simple unaligned watchpoint45shows some examples Not requiredExample 11-11 Entering debug state Debug state entryExample 11-10 Single-stepping off an instruction Debug state exit Example 11-12 Leaving debug stateReading and writing registers through the DCC Accessing registers and memory in debug stateThis section describes the following Example 11-13 Reading an ARM registerReading the Cpsr in debug state Reading the PC in debug stateExample 11-15shows the code to read the PC Example 11-16shows the code for reading the CpsrExample 11-18shows the code for reading a byte of memory Example 11-19 Checking for an abort after memory accessReading memory Example 11-17 Writing the CpsrExample 11-20 Reading a block of bytes of memory Example 11-21 Reading a word of memoryExample 11-24 Writing registers in stall mode Example 11-22 Changing the DTR access modeExample 11-23 Reading registers in stall mode Fast register read/writeFast memory read/write Example 11-25 Reading a block of words of memoryAccessing coprocessor registers Example 11-27 Reading a coprocessor register11-70 Emulating power down Debugging systems with energy management capabilities11-72 FPU Programmer’s Model About the VFPv3-D16 architecture About the FPU programmer’s modelFPU functionality General-purpose registers FPU views of the register bank1shows the VFP system registers in the Cortex-R4F FPU System registersVFPv3 architecture describes the following system registers Mvfr registers are privileged access only All hardware ID information is privileged access onlyFpsid is privileged access only This is a change in VFPv3 compared to VFPv2DNM Floating-Point Status and Control Register, FpscrFpscr Register bit functions RmodeIDE RAZ Floating-Point Exception Register, FpexcLEN DNM IXE RAZ UFE OFE DZE IOE IDCDEX Media and VFP Feature Registers, MVFR0 and MVFR1Floating-Point Exception Register bit functions MVFR0 Register bit functionsMVFR1 Register bit functions Full denormal arithmetic supported for VFPFlush-to-zero mode Full-compliance mode Flush-to-zero mode Default NaN modeFull-compliance mode Default NaN modeIeee 754 standard implementation choices Compliance with the Ieee 754 standardComplete implementation of the Ieee 754 standard NaN handlingQNaN and SNaN handling ComparisonsUnderflow CDPExceptions Integration Test Registers About Integration Test Registers Software access using APB Programming and reading Integration Test RegistersItmiscout Register ItctrlItetmif Itmiscin1110 Processor integration testing1312 Using the Integration Test Registers Performing integration testingItetmif Register ETM interface Itetmif Register bit assignments Bits Name FunctionItmiscout Register bit assignments Bits Name Function Itmiscout Register Miscellaneous OutputsItmiscin Register Miscellaneous Inputs Dbgrestart Integration Mode Control Register ItctrlBits Name Function EtmextoutRAZ/SBZP Bits Access Reset value Name Function7shows the fields of the Itctrl Register IntmodeCycle Timings and Interlock Behavior Multiplies on Divide on Branches onDual issue on About cycle timings and interlock behavior Instruction execution overviewConditional instructions Following sequence where R1 is a Late Reg takes two cyclesFlag-setting instructions Definition of termsAssembler language syntax Takes two cycles because there are no register dependencies Register interlock examplesInstruction Behavior Sequence Takes three cycles because of the result latency of R1Cycle counts if destination is the PC Data processing instructionsCycle counts if destination is not PC Register controlled shifts Example interlocksShifter QADD, QDADD, QSUB, and Qdsub instructions Media data-processing SELResult of the USAD8 instruction Sum of Absolute Differences SADInstruction sequence Behavior USAD8 instructionMultiplies Umlals14-13 Divide Example instruction Cycles Memory Comments Branches10 Branch instruction cycle timing behavior All MRS instructions Mode changingProcessor state updating instructions All MSR instructions to the SpsrSingle load and store instructions 13shows the cycle timing behavior for loads to the PCExample instruction Cycles Memory Result Comments Latency Base register update13 Cycle timing behavior for loads to the PC 14-19 Register offset, then 3-issue cycles Load and Store Double instructionsLoad and Store Multiple instructions Write-backReturn stack prediction Load Multiples, where the PC is in the register listCorrect condition prediction and correct Correct condition prediction and incorrect14-23 RFE and SRS instructions Synchronization instructions ClrexCoprocessor instructions Some instructions such as cache operations take more cyclesSVC formerly SWI Prefetch Abort Undefined InstructionMiscellaneous instructions Serializing Floating-point register transfer instructionsBlocking and serializing Not aligned Floating-point load/store instructionsBit aligned address 2,22,3 4,5Floating-point single-precision data processing instructions Floating-point double-precision data processing instructions Dual issue rules Dual issueDual issue rules Permitted combinations on 28 Permitted instruction combinations Dual issue First instruction Second instruction CasePermitted combinations Multiply-accumulate instructionso Case F2stbAny single-precision CDPi, excluding Case F2DbAC Characteristics Processor timing on Processor timing parameters onProcessor timing Clock uncertainty 10% Processor timing parametersInput port timing parameters Clock uncertainty 50%Clock uncertainty 60% 3shows the timing parameters for the interrupt input ports4shows the input timing parameters for the AXI master port 5shows the input timing parameters for the AXI slave port Rreadys6shows the input timing parameters for the debug input ports 7shows the input timing parameters for the ETM input portsClock uncertainty 40% 8shows the timing parameters for the test input portsClock uncertainty 65% Output ports timing parameters 11shows the timing parameters for the interrupt output ports13shows the timing parameters for the AXI slave output ports Write response channel Clock uncertainty 60%BRESPS10 16shows the timing parameters for the test output ports Clock uncertainty 45%18shows the timing parameters for the FPU output signals Fpidc15-13 Processor Signal Descriptions FPU signals on page A-23From any clock About the processor signal descriptionsAny Signal Direction Clocking Description Global signalsTable A-1 Global signals Table A-2 Configuration signals Configuration signalsTable A-2shows the processor configuration signals InformationTie LOW for even parity Tie High for odd parityRMWENRAM10b Interrupt signals, including VIC interface signals AXI master port L2 interface signalsTable A-4 AXI master port signals for the L2 interface Identification tag for the read address group of signals Identification tag for the write data group of signalsIdentification tag for the write response signal Protection signals provide addition information about a busTable A-6 AXI slave port signals for the L2 interface AXI master port error detection signalsTable A-5 AXI master port error detection signals AXI slave portProtection information, privileged/normal access. ARPROT0 Protection information, privileged/normal access. AWPROT0AXI specification One to 16. a four bit binary value minus one determinesStandard AXI specification AXI slave port error detection signalsATCM, one hot. AWUSERS30 signal is not part Table A-7 AXI slave port error detection signalsTable A-9shows the B0TCM port signals TCM interface signalsTable A-8shows the Atcm port signals = DMA Table A-10shows the B1TCM port signalsTable A-10 B1TCM port signals Write data for B1TCM data RAM B1TCM RAM access is sequentialAddress for B1TCM data RAM Write parity or ECC code for B1TCMTable A-11 Dual core interface signals Dual core interface signalsTable A-11shows the dual redundant core interface signals Table A-12 Debug interface signals Debug interface signalsTable A-13shows the debug miscellaneous signals Input Tie-off Debug self-address offset Table A-13 Debug miscellaneous signalsInput Tie-off Debug ROM physical address valid Input Tie-off Debug self-address offset validTable A-14 ETM interface signals ETM interface signalsTable A-14shows the ETM interface signals Table A-15 Test signals Test signalsTable A-15shows the test signals Mbist signals Table A-16shows the Mbist signalsValidation signals Table A-17shows the validation signalsFPU signals Table A-18 FPU signalsECC Schemes ECC scheme selection guidelines on page B-2ECC scheme selection guidelines Clarified byte-invariant big-endian format NCPUHALT removed from timing diagram Added sectionsRevisions Clarified little-endian formatTable C-1 Differences between issue B and issue C Change LocationTable C-2 Differences between issue C and issue D No technical changesSee also Data Abort, External Abort and Prefetch Abort GlossaryAbort, and an internal or External Abort Base register write-backThat are divisible by four and two respectively See also Advanced High-performance BusSee Advanced High-performance Bus See Advanced Microcontroller Bus ArchitectureActive write transaction Active read transactionActive transfer Completed transferWrite ID capability Read ID widthRead issuing capability Write ID widthSee also Burst See also BeatSee also Word-invariant Accesses are expected to be word-alignedAccessed in parallel during a cache look-up BusSee also Dirty See also Clean See Embedded Trace Macrocell Option chosen does not affect software compatibility An instruction that is architecturally UndefinedBy individual implementations Precision and the fraction is all zerosSee Cold reset Serviced while normal program execution is suspendedSee also Halt mode Result of attempting to access invalid instruction memorySee Should Be Zero Or equal to 1 and is not restricted to being a power of twoSee Should Be One See Boundary scan chainDestination precision See Debug test access portIncrement of +2 User trap handler is executedProcessor-specific. a victim is also known as a cast out Expected behavior for an unaligned accessBit for the exception is set A processorCache terminology diagram