Syntax is close to chisel3, without FIRRTL optimizing and generating readable Verilog code faster.

$ pip3 install knitkit
$ knitkit create hello_knitkit
$ cd hello_knitkit
$ make verilog

Source code in hw/knitkit/src/Mux2.scala and generated in builds/Mux2.v.

Download knitkit-py and then:

$ pip3 install --user knitkit-0.3-py3-none-any.whl

The same as quick install.

Build by SBT or Mill locally. If just have a look, use Scastie online.

1. Create hello_knitkit project directory.

$ mkdir -p hello_knitkit/src/main/scala
$ cd hello_knitkit
$ touch build.sbt

2. Create SBT configuration as below:

lazy val hello = (project in file("."))
  .settings(
    name := "HelloKnitkit",
    scalaVersion := "2.13.6",
    libraryDependencies += "io.github.colin4124" %% "knitkit" % "0.3.0",
  )

3. Write Knitkit source code:

$ touch src/main/scala/Mux2.scala

import knitkit._

class Mux2 extends RawModule {
  val sel = IO(Input(UInt(1.W)))
  val in0 = IO(Input(UInt(1.W)))
  val in1 = IO(Input(UInt(1.W)))
  val out = IO(Output(UInt(1.W)))

  out := (sel & in1) | (~sel & in0)
}

object Main extends App {
  Driver.execute(() => new Mux2, args(0))
}

4. Run SBT, the first argument is generated directory, here is builds.

$ sbt "run builds"

5. Check generated verilog file builds/Mux2.v:

module Mux2 (
  input  sel,
  input  in0,
  input  in1,
  output out
);
  assign out = (sel & in1) | ((~ sel) & in0);
endmodule

1. Create hello_knitkit project directory.

$ mkdir -p hello_knitkit/src
$ cd hello_knitkit
$ touch build.sc

2. Create Mill configuration as below:

import mill._, scalalib._
  
object hello extends ScalaModule {
  def scalaVersion = "2.13.6"
  def millSourcePath = super.millSourcePath / ammonite.ops.up

  def ivyDeps = Agg(
    ivy"io.github.colin4124::knitkit:0.3.0",
  )
}

3. Put source code Mux2.scala to hello_knitkit/src/ directory.

4. Run Mill, hello is the object name in build.sc defined, builds is the first argument where verilog generated.

$ mill hello.run builds

5. Check generated verilog file builds/Mux2.v.

1. Open Scastie website.

2. Click Build Settings in left sidebar.

3. Choose scala 2 in Target, 2.13.6 in Scala Version, search knitkit in Libraries.

4. Click Editor in left sidebar, wirte down:

import knitkit._
  
class Mux2 extends RawModule {
  override def desiredName = "Mux2"
  val sel = IO(Input(UInt(1.W)))
  val in0 = IO(Input(UInt(1.W)))
  val in1 = IO(Input(UInt(1.W)))
  val out = IO(Output(UInt(1.W)))

  out := (sel & in1) | (~sel & in0)
}
Driver.genVerilog(() => new Mux2)

5. Here is the exmple