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Toshiba TX39 user manual System Call exception ∙ Cause, Non-maskable interrupt ∙ Cause

Models: TX39

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Architecture

6.3.10System Call exception

∙Cause

− Execution of an R3900 Processor Core SYSCALL instruction.

∙Exception mask

The System Call exception is not maskable.

∙Applicable instructions

SYSCALL

∙Processing

−The common exception vector (0x8000 0080) is used.

−Sys(8) is set for ExcCode in the Cause register.

−The EPC register points to the address of the instruction causing the exception. If, however, that instruction is in the branch delay slot (for execution during a branch), the immediately preceding branch instruction address is retained in the EPC register and the Cause register BD bit is set to 1.

6.3.11Non-maskable interrupt

∙Cause

−Occurs at the falling edge of the non-maskable interrupt signal.

∙Exception mask

The Non-maskable exception is not maskable. It is raised regardless of the Status register IEc

bit setting.

∙Processing

−The same special interrupt vector as for Reset (0xBFC0 0000), residing in an area that is not cached, is used. It is therefore not necessary for hardware to initialize cache memory in order to process this exception.

−Unlike the Reset exception, here the Status register NmI bit is set.

−As with other exceptions (except for the Reset exception), the NmI exception occurs at an instruction boundary. If a Non-maskable interrupt occurs during a bus cycle, interrupt processing waits until the bus cycle has ended.

−All register contents are retained except for the following.

°The EPC register points to the address of the instruction causing the exception. If, however, that instruction is in the branch delay slot (for execution during a branch), the immediately preceding branch instruction address is retained in the EPC register and the Cause register BD bit is set to 1.

°The Status register NmI bit is set to 1.

°The Config register Halt bit and Doze hit are cleared to 0.

°The Cause register CE bit and ExcCode are undefined.

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Toshiba TX39 user manual System Call exception ∙ Cause, Non-maskable interrupt ∙ Cause

Contents

TX39 Family Core Architecture Page Toshiba Contents EPC Exception Program Counter register Memory location of exception vectorsAppendix a Instruction Set Details Coprocessor Unusable exceptionBus Interface Unit Bus Controller / Write Buffer 229 227Bus request and bus grant 227 Cache snoop 228 230Architecture Architecture Introduction FeaturesHigh-performance Risc techniques Low power consumption Mathematical notation Signal notationNotation Used in This Manual Data notationArchitecture Architecture OverviewRegisters CPU registersCP0 registers Reserved † Exception program counterSource register 5 bits Instruction Set OverviewOperation code 6 bits Destination register 5 bitsJump/branch Load/storeComputational CoprocessorALU Immediate Computational InstructionsALU 3-operand, register type Coprocessor Instructions Multiply/DivideJump/Branch Instructions Special InstructionsSpecial Instruction CP0 instructions Instruction Description CP0 InstructionsData Formats and Addressing Big endian and little endian formatsArchitecture Byte addresses of a misaligned word Pipeline Processing Overview Memory Management Unit MMU User modeKernel mode 1 R3900 Processor Core operating modesKseg0 Direct segment mappingKuseg Kseg1Address mapping Architecture Instruction Formats Instruction Set OverviewInstruction Notation Byte specifications for load and store instructions Load and Store InstructionsBase Offset Sync Computational Instructions NOR SLLV, SRLV, Srav Instruction Format and Description MFHI, Mflo Instruction Format and Description MTHI, Mtlo Instruction Format and DescriptionArchitecture Jump instructions Jump/Branch InstructionsInstruction Format and Description Instruction in the delay slot is executed during the jump 10. Branch instructionsArchitecture Special Instructions 11. Special instructionsCOPz Instruction Format and Description Coprocessor InstructionsBCzT, BCzF Instruction Format and Description Architecture 13. System control coprocessor CP0 instructions Restore FromSystem Control Coprocessor CP0 Instructions Cache Instruction Format and DescriptionPipeline Architecture Delayed load Delay SlotDelayed branching Nonblocking Load Function Nonblocking load functionDivide Instruction DIV, Divu StreamingMemory Management Unit MMU R3900 Processor Core Operating ModesDirect Segment Mapping Internal MMU virtual address spaceKuseg 512MB Exception Processing Utlb TLBL2 Status register Exception Processing RegistersCause register Cache registerBits Mnemonic Field name Description Cause register register no.13Read/Write ExcCode field Mnemonic CauseField name Description Status register register no.12Bits ReadStatus register 1/2 Bits Mnemonic Field name Description Value on Read NmI Non-maskable Interrupt KUc/KUp/KUo Kernel/User mode current/previous/oldIEc/IEp/IEo Interrupt Enable current/previous/old IntMask Interrupt MaskCache register register no.7 Cache registerDALc/DALp/DALo Data Cache Auto-Lock current/previous/old IAL DAL Shows how the RFE instruction works BadVAddr Bad Virtual Address register register no.8 PRId Processor Revision Identifier register register no.15Config Configuration register register no.3 21-1910. Config register2/2 Exception Details ∙ Applicable instructions Address Error exception ∙ Causes∙ Exception mask ∙ ProcessingBreakpoint exception ∙ Cause ∙ ServicingBus Error exception ∙ Causes Architecture Coprocessor Unusable exception ∙ Cause Interrupts ∙ Cause Overflow exception ∙ Cause Reserved Instruction exception ∙ CauseReset exception ∙ Cause System Call exception ∙ Cause Non-maskable interrupt ∙ CauseArchitecture Return from Exception Handler Priority of ExceptionsPriority of Exceptions Exception Mnemonic Architecture Caches Instruction CacheData cache configuration Data CacheLock function Lock bit settingOperation during lock Lock bit clearing Auto-lock bitsCache flushing Cache Test FunctionCache disabling ExampleCache Refill Cache refillCache Snoop Architecture Debugging Functions System Control Processor CP0 RegistersPRId Processor revision ID Debug †† Debug exception control Depc ††DM Debug Mode 0 at reset DBD Debug Branch DelayDebug register register no.16 NIS Non-maskable Interrupt Status BsF Bus Error Exception FlagSSt Single at reset OES Other Exceptions StatusTypes of debug exceptions Debug ExceptionsDSS bit Debug Single Step DSSBranching to a debug exception handler Ii Debug exception handler executionExecuting a Deret instruction Iii Return from a debug exception handlerException priorities Single Step exception ∙ Cause Details of Debug Exceptions∙ Exception masking ∙ Instruction causing this exception Debug Breakpoint exception ∙ CauseArchitecture Appendix a Instruction Set Details Instruction Classes Instruction Formats Instruction Notation Conventions Twos complement division Bitwise logical XOR operationExamples of Instruction Notation Table A-2. Common Load/Store Functions Function MeaningHalfword access 16 bits Word access 32 bitsTriplebyte access 24 bits Byte access 8 bitsJump and Branch Instructions ADD Addi Addiu Addu Rd, rs, rt Andi BCzF Operation Code Bit Encoding BCzFL 111 BCzT 113 BCzTL 115 BEQ Beql Bgez Bgezal Bgezall Bgezl Bgtz Bgtzl Blez Blezl Bltz Bltzal Bltzall Bltzl BNE Bnel Break Bit# Cache Name DataBit# Cache Operation Description Name CFCz COPz COPzCTCz Deret DIV Divu Jump JAL Jalr JR rs LB rt, offsetbase LBU LH rt, offsetbase LHU LUI LW rt, offsetbase LWL 152 LWR 154 Multiply/Add Maddu MFC0 MFCz MFCzMFCz Mfhi Mflo MTC0 MTCz MTCzMthi Mtlo Mult Multu NOR Or rd, rs, rt ORI RFE SB rt, offsetbase Sdbbp SH rt, offsetbase SLL Sllv SLT Slti Sltiu Sltu SRA Srav SRL Srlv SUB Subu SW rt, offsetbase SWL 189 SWR 191 Sync Syscall XOR Xori Special function OPcodeCOPz rs COPz rt CP0 FunctionNotation TMPR3901F 200 On-chip peripheral circuits R3900 Processor CoreBus interface for ease of system implementation Maximum operating frequency Low power consumption, optimal for portable applicationsDebugging support functions on chip PackageBus interface unit bus controller / write buffer Internal BlocksR3900 Processor Core Clock generator Address protection unit204 R3900 Processor Core ConfigurationInstruction Iimitations Clock Generator Address mappingSync NOP Address Protection Unit Registers Break Address register BAddr0-1Break Mask register BMsk0-1 Break Control register BCnt0-1Break Status register BSts Memory protection exceptionRegister address map Debug Support UnitSynchronizer BSts 0xFF00 BAddr0 Bcnt0 BMsk0 BAddr1 Bcnt1 BMsk1INT* signal synchronization INT50NMI* signal synchronization CPCOND* signal synchronization CPCOND31Pins Halt signal. Indicates that TMPR3901F is in halt mode Enables internal PLL clockMode quadruple frequency of crystal oscillator Doze signal. Indicates that TMPR3901F is in doze mode∙ Master Clock OperationsClock ∙ Processor ClockSystem clock Master clock ProcessorClock Read Operation Single ReadBus error during a single read operation Burst Read Burst read 4 words 1 wait Bus error in burst read operation 4 words Write Operation Single write operation 2 waitsInterrupts 1 NMI2 INT50 InterruptBus Arbitration Bus request and bus grantBUSGNT*L Reset Half-Speed Bus Mode Single read operation in half-speed bus modePower-Down Mode Halt mode232 Standby Mode Standby mode PLL stopDoze Mode Reduced Frequency Mode