finite-wasm 0.6.1

Guarantee deterministic limits on execution time and space resources made available to the WebAssembly programs in a runtime-agnostic way. 
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open Types
open Values

type size = int32
type index = int32
type count = int32

type table = {mutable ty : table_type; mutable content : ref_ array}
type t = table

exception Type
exception Bounds
exception SizeOverflow
exception SizeLimit
exception OutOfMemory

let valid_limits {min; max} =
  match max with
  | None -> true
  | Some m -> I32.le_u min m

let create size r =
  try Lib.Array32.make size r
  with Out_of_memory | Invalid_argument _ -> raise OutOfMemory

let alloc (TableType (lim, _) as ty) r =
  if not (valid_limits lim) then raise Type;
  {ty; content = create lim.min r}

let size tab =
  Lib.Array32.length tab.content

let type_of tab =
  tab.ty

let grow tab delta r =
  let TableType (lim, t) = tab.ty in
  assert (lim.min = size tab);
  let old_size = lim.min in
  let new_size = Int32.add old_size delta in
  if I32.gt_u old_size new_size then raise SizeOverflow else
  let lim' = {lim with min = new_size} in
  if not (valid_limits lim') then raise SizeLimit else
  let after = create new_size r in
  Array.blit tab.content 0 after 0 (Array.length tab.content);
  tab.ty <- TableType (lim', t);
  tab.content <- after

let load tab i =
  try Lib.Array32.get tab.content i with Invalid_argument _ -> raise Bounds

let store tab i r =
  let TableType (lim, t) = tab.ty in
  if type_of_ref r <> t then raise Type;
  try Lib.Array32.set tab.content i r with Invalid_argument _ -> raise Bounds

let blit tab offset rs =
  let data = Array.of_list rs in
  try Lib.Array32.blit data 0l tab.content offset (Lib.Array32.length data)
  with Invalid_argument _ -> raise Bounds