mrLSD / riscv-fs, Hacker News

Copyright © Evgeny Ukhanov

This is a formal (and executable) specification for the RISC-V ISA (Instruction Set Architecture), written in F # purely functional style. We deliberately choose an “extremely elementary” implementation of F # to make it readable and usable by wide audience who do not know F # and who do not plan to learn F #.

This is a work-in-progress, one of several similar concurrent efforts within theISA Formal SpecificationTechnical Group constituted by The RISC-V Foundation (https://riscv.org). We welcome your feedback, comments and suggestions.

Content

• Features & Current status
• Reading the code
• How to build and run it on RISC-V binaries
  • Install .NET SDK
  • Make the application executable
  • Run the application executable
• License

Features & Current status

• Supports the following features
  • Base instruction sets: RV 32 I
• Features under development
  • Base instruction sets: RV 64 I
  • Standard extension M (integer multiply / divide)
  • Standard extension A (atomic memory ops)
  • Standard extension C (Compressed 16 – bit instructions)
  • Standard extension F (Single-precision floating point)
  • Standard extension D (Double-precision floating point)
  • Privilege Level M (Machine)
  • Privilege Level U (User)
  • Privilege Level S (Supervisor)
    • Virtual Memory schemes SV 32, SV 39 and SV 48
• Application can be executed as a F # program flexible with CLI (command line interface) support, which in turn executes RISC-V ELF binaries. This is a sequential interpretation: one-instruction-at-a-time, sequential memory model.
• Tests passing for RISC-Vunder development:
  • Basic instruction flow
  • RV 32 ui-p- *, ​​rv 64 ui-p - *(Base instruction set)
  • RV 32 um-p- *, ​​rv 64 um-p - *(M extension )
  • RV 32 ua-p- *, ​​RV 64 ua-p - *(A extension )
  • RV 32 UC-P- *, RV 64 uc-p - *(C extension )

Reading the code

We expect that many people might use this as a reading reference (whether or not they build and execute it) to clarify their understanding of RISC-V ISA semantics.

Main part for reading Specification:

• Decode * .fs

  Decodes contain decoders for specific instructions set and notified with instruction / extention set symbol. For exampleDecodeI.fs

• Execute * .fs

  Executes contain executions for specific instructions set and notified with instruction / extention set symbol. For exampleExecuteI.fs

• Utilities:

  • CLI.fs

    Contain helper function and types for building effective CLI commands and options.

  • Bits.fs

    Basic type specific functions for manipulations withbits.

  • Run.fs

    Basic Run flow – fetch, decode, execute, logging execution flow. *********

• Architecture

  • Arch.fs

    Basic architecture types for RISC-V specification.

  • MachineState.fs

    Basic type and functions described RISC-V machine state.

• Main app

  • Program.fs

  Main application to executeRISC-V simulator / emulator.

• Test

  • Test / *. Fs

    Contain unit-tests for instuctions set and extensions

  • Test / asm /

    Contain Assembler test programs for manual testing RISC-V CPI implementation. It depend onrisc-v toolchainand it has special auto-buildMake file.

How to build and run it on RISC-V binaries

Application can be executed as asequential RISC-V simulator(sequential, one-instruction-at-a-time semantics), by building and executing it as a standard F # program.

Supported OS:

• Linux
• Windows
• MacOS

Supported.NET SDK:

• . NET SDK 2.2
• .NET SDK 3.0

Install .NET SDK

For Windows preferred way to use Visual Studio.

Other examples will be for Linux. Please follow to instructionhttps: / /dotnet.microsoft.com/download

For Ubuntu:

$ wget -q https://packages.microsoft.com/config/ubuntu/ 04 / packages-microsoft-prod.deb -O packages-microsoft-prod.deb $ sudo dpkg -i packages-microsoft-prod.deb $ sudo apt-get update $ sudo apt-get install apt-transport-https $ sudo apt-get update $ sudo apt-get install dotnet-sdk-3.0

To check installation:

$ dotnet --version

will tell you what version of (dotnet) you have.

Make the application executable

Then, you can build the application executable with:

$ dotnet build

Run the application executable

Most simple way run immediatelyrun(without additionalbuildcommand) to see command-line options on the executable:

$ dotnet run - --help

If you run the application without option, like thet:

$ dotnet run

You’ll receive error message:

Example to run specific ISA with extentions, verbosity output and ELF file for execution in RISC-V CPI simulator:

$ dotnet run - -A rv 32 i - v myapp.elf

Wrong parameters put –help to get more information

License

MIT License