unikernel/duniverse/ocaml-re/lib/bit_vector.ml

@@ -0,0 +1,48 @@
+type t =
+  { len : int
+  ; bits : Bytes.t
+  }
+
+let byte s i = Char.code (Bytes.unsafe_get s i)
+let set_byte s i x = Bytes.unsafe_set s i (Char.chr x)
+let length t = t.len
+
+let unsafe_set v n b =
+  let i = n lsr 3 in
+  let c = byte v.bits i in
+  let mask = 1 lsl (n land 7) in
+  set_byte v.bits i (if b then c lor mask else c land lnot mask)
+;;
+
+let set v n b =
+  if n < 0 || n >= v.len then invalid_arg "Bit_vector.set";
+  unsafe_set v n b
+;;
+
+let unsafe_get v n =
+  let i = n lsr 3 in
+  byte v.bits i land (1 lsl (n land 7)) > 0
+;;
+
+let get v n =
+  if n < 0 || n >= v.len then invalid_arg "Bit_vector.get";
+  unsafe_get v n
+;;
+
+let reset_zero t = Bytes.fill t.bits 0 (Bytes.length t.bits) '\000'
+
+let create_zero len =
+  let bits =
+    let r = len land 7 in
+    let q = len lsr 3 in
+    let len = if r = 0 then q else q + 1 in
+    Bytes.make len '\000'
+  in
+  { len; bits }
+;;
+
+let pp fmt { len; bits } =
+  let len fmt () = Fmt.sexp fmt "len" Fmt.int len in
+  let bits fmt () = Fmt.sexp fmt "bits" Fmt.bytes bits in
+  Format.fprintf fmt "%a@.%a@." len () bits ()
+;;