package clz

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Source file clz_decompress.ml

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(*
  Mostly from deflate.gz documentation :) 
  If somebody cares, we could abstract them over Cohttp and Lwt
  and have an implementation that can work with streamed response bodies
  and does directly output to file.
  The current dumb implementation is more than enough for my limited needs.
*)

let inflate_string_de str =
  let i = De.bigstring_create De.io_buffer_size in
  let o = De.bigstring_create De.io_buffer_size in
  let w = De.make_window ~bits:15 in
  let r = Buffer.create 0x1000 in
  let p = ref 0 in
  let refill buf =
    let len = min (String.length str - !p) De.io_buffer_size in
    Bigstringaf.blit_from_string str ~src_off:!p buf ~dst_off:0 ~len;
    p := !p + len;
    len
  in
  let flush buf len =
    let str = Bigstringaf.substring buf ~off:0 ~len in
    Buffer.add_string r str
  in
  match De.Higher.uncompress ~w ~refill ~flush i o with
  | Ok () -> Ok (Buffer.contents r)
  | Error _ as err -> err

let deflate_string_de str =
  let i = De.bigstring_create De.io_buffer_size in
  let o = De.bigstring_create De.io_buffer_size in
  let w = De.Lz77.make_window ~bits:15 in
  let q = De.Queue.create 0x1000 in
  let r = Buffer.create 0x1000 in
  let p = ref 0 in
  let refill buf =
    (* assert (buf == i); *)
    let len = min (String.length str - !p) De.io_buffer_size in
    Bigstringaf.blit_from_string str ~src_off:!p buf ~dst_off:0 ~len;
    p := !p + len;
    len
  in
  let flush buf len =
    (* assert (buf == o); *)
    let str = Bigstringaf.substring buf ~off:0 ~len in
    Buffer.add_string r str
  in
  De.Higher.compress ~w ~q ~refill ~flush i o;
  Buffer.contents r

let inflate_string_gz str =
  let i = De.bigstring_create De.io_buffer_size in
  let o = De.bigstring_create De.io_buffer_size in
  let r = Buffer.create 0x1000 in
  let p = ref 0 in
  let refill buf =
    let len = min (String.length str - !p) De.io_buffer_size in
    Bigstringaf.blit_from_string str ~src_off:!p buf ~dst_off:0 ~len;
    p := !p + len;
    len
  in
  let flush buf len =
    let str = Bigstringaf.substring buf ~off:0 ~len in
    Buffer.add_string r str
  in
  Gz.Higher.uncompress ~refill ~flush i o
  |> Result.map (fun _metadata -> Buffer.contents r)

let deflate_string_gz ~cfg ?(level = 4) str =
  let i = De.bigstring_create De.io_buffer_size in
  let o = De.bigstring_create De.io_buffer_size in
  let w = De.Lz77.make_window ~bits:15 in
  let q = De.Queue.create 0x1000 in
  let r = Buffer.create 0x1000 in
  let p = ref 0 in
  let refill buf =
    let len = min (String.length str - !p) De.io_buffer_size in
    Bigstringaf.blit_from_string str ~src_off:!p buf ~dst_off:0 ~len;
    p := !p + len;
    len
  in
  let flush buf len =
    let str = Bigstringaf.substring buf ~off:0 ~len in
    Buffer.add_string r str
  in
  Gz.Higher.compress ~level ~w ~q ~refill ~flush () cfg i o;
  Buffer.contents r