extern_mem.ml

open Owi

(* an extern module that will be linked with a wasm module *)
let extern_module : Concrete_value.Func.extern_func Link.extern_module =
  (* some custom functions *)
  let memset m start byte length =
    let rec loop offset =
      if Int32.le offset length then begin
        Concrete_memory.store_8 m ~addr:(Int32.add start offset) byte;
        loop (Int32.add offset 1l)
      end
    in
    loop 0l
  in
  let print_x64 (i : int64) = Printf.printf "0x%LX\n%!" i in
  (* we need to describe their types *)
  let functions =
    [ ( "print_x64"
      , Concrete_value.Func.Extern_func (Func (Arg (I64, Res), R0), print_x64)
      )
    ; ( "memset"
      , Concrete_value.Func.Extern_func
          (Func (Mem (Arg (I32, Arg (I32, Arg (I32, Res)))), R0), memset) )
    ]
  in
  { functions }

(* a link state that contains our custom module, available under the name `chorizo` *)
let link_state =
  Link.extern_module Link.empty_state ~name:"chorizo" extern_module

(* a pure wasm module refering to `$extern_mem` *)
let pure_wasm_module =
  match Parse.Text.Module.from_file (Fpath.v "extern_mem.wat") with
  | Error _ -> assert false
  | Ok modul -> modul

(* our pure wasm module, linked with `chorizo` *)
let module_to_run, link_state =
  match
    Compile.Text.until_link link_state ~unsafe:false ~rac:false ~srac:false
      ~optimize:true ~name:None pure_wasm_module
  with
  | Error _ -> assert false
  | Ok v -> v

(* let's run it ! it will print the values as defined in the print_i64 function *)
let () =
  match Interpret.Concrete.modul link_state.envs module_to_run with
  | Error _ -> assert false
  | Ok () -> ()