open import Basic_classes
open import Bool
open import Num
open import Show

open import Error

declare {ocaml} rename module = bitstring_local

type bitstring

declare ocaml target_rep type bitstring = `Bitstring.bitstring`

(** [empty] is the empty bitstring.
  *)
val empty : bitstring

declare ocaml target_rep function empty = `Bitstring.empty`

(** [zeros m] creates a bitstring of length [m] containing all zeros.
  *)
val zeros : nat -> bitstring

declare ocaml target_rep function zeros = `Bitstring.create_bitstring`

(** [create m c] creates a bitstring of length [m] containing all [c]
  * characters.
  *)
val create : nat -> char -> bitstring

declare ocaml target_rep function create = `Bitstring.make_bitstring`

(** [concat xs] concatenates a list of bitstrings [xs] into a single bitstring.
  *)
val concat : list bitstring -> bitstring

declare ocaml target_rep function concat = `Bitstring.concat`

(** [acquire fname] acquires a bitstring from a binary file, located at [fname].
  *)
val acquire : string -> error bitstring

declare ocaml target_rep function acquire = `Ml_bindings.acquire_bitstring`

(** [length bs0] returns the length of bitstring [bs0].
  *)
val length : bitstring -> nat

declare ocaml target_rep function length = `Bitstring.bitstring_length`

(** [partition offset bs0] cuts [bs0] into two pieces at offset [offset].  Throws
  * an exception if 
  *)
val partition : nat -> bitstring -> (bitstring * bitstring)

declare ocaml target_rep function partition = `Ml_bindings.partition_bitstring`

(** [offset_and_cut offset size bs0] cuts a [size]-lengthed bitstring out of [bs0]
  * at offset [offset].
  *)
val offset_and_cut : nat -> nat -> bitstring -> bitstring
let offset_and_cut offset size bs0 =
  let (_, cut) = partition offset bs0 in
  let (rel, _) = partition size cut in
    rel

(** [equal bs0 bs1] tests whether [bs0] and [bs1] are equal.
  *)
val equal : bitstring -> bitstring -> bool

declare ocaml target_rep function equal = unsafe_structural_equality

(** [string_of_bitstring bs0] produces a string-based representation of bitstring
  * [bs0].
  *)
val string_of_bitstring : bitstring -> string

declare ocaml target_rep function string_of_bitstring = `Bitstring.string_of_bitstring`

instance (Eq bitstring)
  let (=) = equal
  let (<>) l r = not (equal l r)
end

instance (Show bitstring)
  let show = string_of_bitstring
end