Clash Cores

Warning: Still under construction

This repository contains a number of existing useful circuits written in Clash.

These circuits include:

• SPI core
• UART core
• CRC core
• Etherbone core
• 8b10b line encoder/decoder
• SGMII PCS receiver/transmitter
• Various wrappers around xilinx IPs (blockram, dcfifo, floating, ila, xpm ...)

Note: The SGMII circuits require clash-prelude >= 1.9.0 and will be skipped if built against an earlier version of Clash.

This code was originally a sub-folder within the clash-compiler repo, but now it's being moved into its own repository. This move is still in progress. You can see the current status of move here.

If you're looking for a pre-built Clash circuit and don't find it here, you can also check out Clash Protocols to see if it exists there.

You can also look through Adam Walker's excellent list of prebuilt Clash circuits and other community projects on Clash's ecosystem page.

Nix

This project exposes several Nix flake outputs. Most notably the clash-cores package, exposed individually or as an overlay (which you need to apply on top of clash-compiler).

Contributing to clash-cores can be done via the developer shell exposed by the Nix flake. Open a terminal and type: nix develop. Optionally a specific GHC version can be selected as well as a -minimal or -full version. The -minimal shell does NOT contain the Haskell Language Server, whilst the -full shell does. When using the developer shell, do not forget to remove the cabal.project file. This file contains a package source and Cabal prioritizes local package sources over Nix sources. Removing the cabal.project file should work fine when developing with Nix.

You can also add this project as a Nix-dependency. This project depends on clash-compiler, the recommended way to add this to your project as a Nix dependency is as follows:

First add clash-compiler and clash-cores to your flake inputs:

inputs = {
  clash-compiler.url = "github:clash-lang/clash-compiler"
  clash-cores = {
    url = "github:clash-lang/clash-cores"
    inputs.clash-compiler.follows = "clash-compiler";
  };
};

It is important to have clash-cores follow the same clash-compiler version as your project, this ensures you do not get different Haskell package hashes. Afterwards, use the clashPackages as a baseline for your Haskell packages and overlay this project's overlay on top of it:

let
  # The GHC version you would like to use
  # This has to be be one of the supported versions of clash-compiler
  compiler-version = "ghc9101";

  # Import the normal and Haskell package set from clash-compiler
  pkgs = (import clash-compiler.inputs.nixpkgs {
    inherit system;
  }).extend clash-compiler.overlays.${compiler-version};
  clash-pkgs = pkgs."clashPackages-${compiler-version}";

  # Define your Haskell package
  overlay = final: prev: {
    # Your haskell package here
    my-package = prev.developPackage {
      root = ./my-source;
      overrides = _: _: final;
    };
  }
  # Make sure to include the clash-cores overlay!
  # This is what brings the clash-cores packages into scope
  // clash-cores.overlays.${system}.default final prev;

  # The final Haskell package set, containing your project as well as all Clash dependencies
  hs-pkgs = clash-pkgs.extend overlay;
in
  {
    # .. your outputs
  }

And that's it!