Module Hardcaml_verilator

Verilator backend for Hardcaml cycle simulations.

While this performs faster than Hardcaml's Cyclesim, it takes a longer time to elaborate the design (a ~3_000 LoC verilog file takes around 2 seconds, whilist hardcaml's Cyclesim takes 0.1 second). The default is to run it in non-thread safe mode (ie: single threaded w/o atomics / locks), which is the preferred option for small designs. The create and With_interface.create functions do the following:

0. Generates the verilog file of the circuit 1. Calls verilator to generate C++ file for simulation 3. Generates C-wrapper for accessing fields in the C++ data structure 4. Compiles the generated C++ file and C-wrapper to make a shared library 5. Dyanmically load the shared library back to the same executable and bind the > functions using C-types 6. Create a Cyclesim.t instance by supplying the relevant functions with bindings to > verilator

module Cache : sig ... end
module Simulation_backend : sig ... end
type t = {
input_setters : (string * ( Hardcaml.Bits.t -> unit )) list;
output_getters : (string * ( unit -> Hardcaml.Bits.t )) list;
internal_getters : (string * ( unit -> Hardcaml.Bits.t )) list;
eval : unit -> unit;
complete : unit -> unit;
}
type 'a with_options = ?cache:Cache.t -> ?build_dir:string -> ?verbose:bool -> ?optimizations:bool -> ?threads:[ `Non_thread_safe | `With_threads of int ] -> ?config:Hardcaml.Cyclesim.Config.t -> 'a

Arguments when creating a verilator simulation object.

  • build_dir specifies the directory. Defaults to somewhere in /tmp
  • cache_dir specifies a location to store compiled shared libraries. When cache_dir is set, the create functions below first tries to check if an existing compilation for the current circuit exists in the specified cache_dir. This can speed up compilation for repeated simulation runs.
val compile_circuit_and_load_shared_object : ( Hardcaml.Circuit.t -> t ) with_options
val create : ( clock_names:string list -> Hardcaml.Circuit.t -> Hardcaml.Cyclesim.t_port_list ) with_options