Config register2/2 | Toshiba TX39 specification

Architecture

Bits		Mnemonic	Field name	Description	Value on	Read/
Bits		Mnemonic	Field name	Description	Reset	Write
					Reset	Write
8		Halt††	Halt	Setting this bit to 1 puts the R3900	0	Read/
				Processor Core in Halt mode. This		Write
				state is canceled by a Reset exception
				when a reset signal is received, or
				when cancelled by a non-maskable
				interrupt signal or interrupt signal that
				clears the Halt bit to 0. The Halt bit is
				cleared even if interrupts are masked.
				Data cache snoops are not possible in
				Halt mode. Halt mode reduces power
				consumption to a greater extent than
				Doze mode.
7		Lock	Lock Config	Setting this bit to 1 prevents further	0	Reset
			register	writes to the Config register. This bit
				is cleared to 0 by a Reset exception.
				If a store instruction is used to set other
				bits at the same time as the Lock bit,
				the other settings are valid.
6		DCBR	Data Cache Burst	1:Indicates that the value in the	0	Read/
			Refill	DRSize field of the Config register		Write
				should be used as the data cache
				refill size.
				0:The data cache refill size is 1 word (4
				bytes).
5		ICE	Instruction Cache	Setting this bit to 1 enables the	1	Read/
			Enable	instruction cache.		Write
4		DCE	Data Cache	Setting this bit to 1 enables the data	1	Read/
			Enable	cache.		Write
3-2		IRSize	Instruction Burst	These bits designate the instruction	00	Read/
			Refill Size	cache burst refill size as follows.		Write
				00: 4 words (16 bytes)
				01: 8 words (32 bytes)
				10: 16 words (64 bytes)
				11: 32 words (128 bytes)
1-0		DRSize	Data Burst Refill	These bits indicate the data cache	00	Read/
			Size	burst refill size as follows. (This		Write
				setting is valid only when the DCBR bit
				in the Config register is set to 1.)
				00: 4 words (16 bytes)
				01: 8 words (32 bytes)
				10: 16 words (64 bytes)
				11: 32 words (128 bytes)
31-22,		0		Ignored on write; 0 when read	0	Read
15-12
Note :	† After modifications to DCBR, ICE, DCE, IRSize or DRSize, the new cache configuration takes effect after
	completion of the currently executing bus operation (cache refill).

††Operation is undefined when both Doze bit and Halt bit are set to 1.

Figure 6-10. Config register(2/2)

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Image 72

Toshiba TX39 user manual Config register2/2

Contents

TX39 Family Core Architecture Page Toshiba Contents EPC Exception Program Counter register Memory location of exception vectors Appendix a Instruction Set Details Coprocessor Unusable exception Bus Interface Unit Bus Controller / Write Buffer 227 Bus request and bus grant 227 Cache snoop 228229 230 Architecture Architecture Features IntroductionHigh-performance Risc techniques Low power consumption Signal notation Notation Used in This ManualMathematical notation Data notation Architecture Architecture Overview Registers CPU registers CP0 registers Reserved † Exception program counter Instruction Set Overview Operation code 6 bitsSource register 5 bits Destination register 5 bits Load/store ComputationalJump/branch Coprocessor Computational Instructions ALU ImmediateALU 3-operand, register type Multiply/Divide Jump/Branch InstructionsCoprocessor Instructions Special Instructions Special Instruction CP0 instructions Instruction Description CP0 Instructions Data Formats and Addressing Big endian and little endian formats Architecture Byte addresses of a misaligned word Pipeline Processing Overview User mode Kernel modeMemory Management Unit MMU 1 R3900 Processor Core operating modes Direct segment mapping KusegKseg0 Kseg1 Address mapping Architecture Instruction Set Overview Instruction FormatsInstruction Notation Byte specifications for load and store instructions Load and Store Instructions Base Offset Sync Computational Instructions NOR SLLV, SRLV, Srav Instruction Format and Description MFHI, Mflo Instruction Format and Description MTHI, Mtlo Instruction Format and Description Architecture Jump/Branch Instructions Jump instructionsInstruction Format and Description Instruction in the delay slot is executed during the jump 10. Branch instructions Architecture Special Instructions 11. Special instructions Coprocessor Instructions COPz Instruction Format and DescriptionBCzT, BCzF Instruction Format and Description Architecture Restore From System Control Coprocessor CP0 Instructions13. System control coprocessor CP0 instructions Cache Instruction Format and Description Pipeline Architecture Delay Slot Delayed loadDelayed branching Nonblocking Load Function Nonblocking load function Divide Instruction DIV, Divu Streaming Memory Management Unit MMU R3900 Processor Core Operating Modes Direct Segment Mapping Internal MMU virtual address space Kuseg 512MB Exception Processing Utlb TLBL2 Exception Processing Registers Cause registerStatus register Cache register Cause register register no.13 Bits Mnemonic Field name DescriptionRead/Write ExcCode field Mnemonic Cause Status register register no.12 BitsField name Description Read Status register 1/2 Bits Mnemonic Field name Description Value on Read KUc/KUp/KUo Kernel/User mode current/previous/old IEc/IEp/IEo Interrupt Enable current/previous/oldNmI Non-maskable Interrupt IntMask Interrupt Mask Cache register register no.7 Cache register DALc/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.15 Config Configuration register register no.3 21-19 10. Config register2/2 Exception Details Address Error exception ∙ Causes ∙ Exception mask∙ Applicable instructions ∙ Processing Breakpoint exception ∙ Cause ∙ Servicing Bus Error exception ∙ Causes Architecture Coprocessor Unusable exception ∙ Cause Interrupts ∙ Cause Overflow exception ∙ Cause Reserved Instruction exception ∙ Cause Reset exception ∙ Cause System Call exception ∙ Cause Non-maskable interrupt ∙ Cause Architecture Priority of Exceptions Return from Exception HandlerPriority of Exceptions Exception Mnemonic Architecture Caches Instruction Cache Data cache configuration Data Cache Lock bit setting Lock functionOperation during lock Lock bit clearing Auto-lock bits Cache Test Function Cache disablingCache flushing Example Cache Refill Cache refill Cache Snoop Architecture Debugging Functions System Control Processor CP0 Registers PRId Processor revision ID Debug †† Debug exception control Depc †† DBD Debug Branch Delay DM Debug Mode 0 at resetDebug register register no.16 BsF Bus Error Exception Flag SSt Single at resetNIS Non-maskable Interrupt Status OES Other Exceptions Status Debug Exceptions DSS bitTypes of debug exceptions Debug Single Step DSS Branching to a debug exception handler Ii Debug exception handler execution Iii Return from a debug exception handler Executing a Deret instructionException priorities Details of Debug Exceptions Single Step exception ∙ Cause∙ Exception masking ∙ Instruction causing this exception Debug Breakpoint exception ∙ Cause Architecture Appendix a Instruction Set Details Instruction Classes Instruction Formats Instruction Notation Conventions Twos complement division Bitwise logical XOR operation Examples of Instruction Notation Table A-2. Common Load/Store Functions Function Meaning Word access 32 bits Triplebyte access 24 bitsHalfword access 16 bits Byte access 8 bits Jump 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 Data Bit# Cache Operation Description Name CFCz COPz COPz CTCz 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 MFCz MFCz Mfhi Mflo MTC0 MTCz MTCz Mthi 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 OPcode Special functionCOPz rs COPz rt CP0 Function Notation TMPR3901F 200 R3900 Processor Core On-chip peripheral circuitsBus interface for ease of system implementation Low power consumption, optimal for portable applications Debugging support functions on chipMaximum operating frequency Package Internal Blocks R3900 Processor Core Clock generatorBus interface unit bus controller / write buffer Address protection unit 204 Configuration R3900 Processor CoreInstruction Iimitations Clock Generator Address mapping Sync NOP Address Protection Unit Registers Break Address register BAddr0-1 Break Mask register BMsk0-1 Break Control register BCnt0-1 Break Status register BSts Memory protection exception Debug Support Unit SynchronizerRegister address map BSts 0xFF00 BAddr0 Bcnt0 BMsk0 BAddr1 Bcnt1 BMsk1 INT* signal synchronization INT50 NMI* signal synchronization CPCOND* signal synchronization CPCOND31 Pins Enables internal PLL clock Mode quadruple frequency of crystal oscillatorHalt signal. Indicates that TMPR3901F is in halt mode Doze signal. Indicates that TMPR3901F is in doze mode Operations Clock∙ Master Clock ∙ Processor Clock Master clock Processor System clockClock Read Operation Single Read Bus 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 waits Interrupts 1 NMI 2 INT50 Interrupt Bus Arbitration Bus request and bus grant BUSGNT*L Reset Half-Speed Bus Mode Single read operation in half-speed bus mode Power-Down Mode Halt mode 232 Standby Mode Standby mode PLL stop Doze Mode Reduced Frequency Mode