hardcaml-examples provides a small framework for creating HardCaml based cores and six example designs. The framework code provides the general plumbing required to create a console based application with features including code generation, simulation, and waveform viewing. A recent update extends the framework so that cores can be run on a webpage.

WebApp Examples

  1. Sorting networks
  2. Linear feedback shift registers
  3. Wallace and Dadda tree multipliers
  4. Prefix networks
  5. ROM-accumulator

Plugging a design into the framework

A design compatible with the framework should implement the signature given in HardCamlFramework.Framework.Design.

module My_design = struct

  let name = "design_name"
  let desc = "design description (in markdown)"

  (* configuration *)
  module Hw_config = struct
    include interface (* design parameters *) end
    let params = (* default parameters *) 
  module Tb_config = struct
    include interface (* testbench parameters *) end
    let params = (* default parameters *) 
  let validate hw tb = (* parameter validation *)
  (* design and testbench construction *)
  module Make
    (B : HardCaml.Comb.S)
    (* user provided parameters *)
    (H : Params with type 'a t = 'a Hw_config.t)
    (T : Params with type 'a t = 'a Tb_config.t) = struct
    module I = interface (* design inputs *) end
    module O = interface (* design outputs *) end
    let wave_cfg = (* configuration of waveform *)
    let hw i = (* design construction *)
    let tb sim i o n = (* testbench *)

A console application can be created as follows

module A = HardCamlFrameworkConsole.App.Make(MyDesign)

The application should be linked with the hardcaml-framework.console ocamlfind library. The following generic options will be available

option description
-vlog generate verilog netlist
-vhdl generate vhdl netlist
-csim generate C simulation model
-tb run testbench
-llvm use LLVM backend to run testbench
-vpi use Icarus Verilog to run testbench
-checktb compare ocaml simulation with LLVM/VPI backend
-interactive interactive text driven testbench mode
-vcd generate VCD file
-waveterm integrated waveform viewer
-gtkwave gtkwave waveform viewer

The remaining options will configure design and testbench parameters.


A web based application is created by building two bytecode applications (linked with hardcaml-framework.js) and compiling them with js_of_ocaml.

user interface (ie mydesign.js)

module A = HardCamlFrameworkJS.Appmain.Make(MyDesign)

webworker (mydesign_ww.js)

module A = HardCamlFrameworkJS.Appww.Make(MyDesign)

To include the application in a html page load the user interface in a script tag and include a div with id hardcaml-framework-webapp and a data attribute called data-hcww which points to the webworker javascript file. The webapp will create itself within the div.

<div data-hcww="mydesign_ww.js" id="hardcaml-framework-webapp"></div>
<script type="text/javascript" src="mydesign.js"></script>