Nios® V Processor Reference Manual

ID 683632
Date 10/02/2023

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4.4.2. Control and Status Registers (CSR) Mapping

Control and status registers report the status and change the behavior of the processor. Since the processor core only supports M-mode and D-mode, Nios® V/g processor implements the CSRs supported by these two modes.

Table 90.  Control and Status Registers List
Number Privilege Name Description
Floating-Point CSRs
0x001 MRW fflags Floating-Point Accrued Exceptions. Refer to Floating-Point CSR Register Fields.
0x002 MRW frm Floating-Point Dynamic Rounding Mode. Refer to Floating-Point CSR Register Fields.
0x003 MRW fcsr Floating-Point Control and Status Register (frm and fflags). Refer to Floating-Point CSR Register Fields.
Machine Trap Setup
0x300 MRW mstatus Machine status register. Refer to Machine Status Register Fields.
0x301 MRW misa ISA and extensions. Refer to Machine ISA Register Fields.
0x304 MRW mie Machine interrupt-enable register. Refer to Machine Interrupt-Enable Register Fields.
0x305 MRW mtvec Machine trap-handler base address. Refer to .Machine Trap-Handler Base Address Register Fields.
Machine Trap Handling
0x341 MRW mepc Machine exception program counter. Refer to Machine Exception Program Counter Register Fields.
0x342 MRW mcause Machine trap cause. Refer to Machine Trap Cause Register Fields.
0x343 MRW mtval Machine bad address or instruction. Refer to Machine Trap Value Register Fields.
0x344 MRW mip Machine interrupt pending. Refer to Machine Interrupt-Pending Register Fields.
Trigger Registers
0x7A0 MRW tselect Trigger select. Refer to Trigger Select Register Fields.
0x7A1 MRW tdata1 (mcontrol) Trigger data 1 (Match Control). Refer to Trigger Data 1 (Match Control) Register Fields.
0x7A2 MRW tdata2 Trigger data 2. Refer to Trigger Data 2 Register Fields.
0x7A4 MRO tinfo Trigger info. Refer to Trigger Info Register Fields.
Debug Mode Registers
0x7B0 DRW dcsr Debug control and status register. Refer to Debug Control and Status Register Fields.
0x7B1 DRW dpc Debug Program Counter. Refer to Debug Program Counter Register Fields.
Machine Information Register
0xF11 MRO mvendorid Vendor ID. Refer to Vendor ID Register Fields.
0xF12 MRO marchid Architecture ID. Refer to Architecture ID Register Fields.
0xF13 MRO mimpid Implementation ID. Refer to Implementation ID Register Fields.
0xF14 MRO mhartid Hardware thread ID. Refer to Hardware Thread ID Register Fields.