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4.3.1. General-Purpose Register File
4.3.2. Arithmetic Logic Unit
4.3.3. Multipy and Divide Units
4.3.4. Floating-Point Unit
4.3.5. Custom Instruction
4.3.6. Reset and Debug Signals
4.3.7. Control and Status Registers
4.3.8. Exception Controller
4.3.9. Interrupt Controller
4.3.10. Memory and I/O Organization
4.3.11. RISC-V based Debug Module
4.3.12. Error Correction Code (ECC)
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.
| 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. |
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