Revision 097f0616d831c063326c9c873c2ff703901502c0 authored by Raphaël Proust on 29 March 2022, 13:21:54 UTC, committed by Raphaël Proust on 07 June 2022, 09:10:38 UTC
1 parent 529d8b0
binary_stream.ml
(*****************************************************************************)
(* *)
(* Open Source License *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com> *)
(* *)
(* Permission is hereby granted, free of charge, to any person obtaining a *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense, *)
(* and/or sell copies of the Software, and to permit persons to whom the *)
(* Software is furnished to do so, subject to the following conditions: *)
(* *)
(* The above copyright notice and this permission notice shall be included *)
(* in all copies or substantial portions of the Software. *)
(* *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *)
(* DEALINGS IN THE SOFTWARE. *)
(* *)
(*****************************************************************************)
(* Facilities to decode streams of binary data *)
type buffer = {buffer : Bytes.t; ofs : int; len : int}
type t = {
current : buffer;
(* buffer queue (classical double list implementation) *)
pending : Bytes.t list;
pending_rev : Bytes.t list;
(* number unread bytes in 'current + pending + pending_rev' *)
unread : int;
}
let is_empty {unread; _} = unread = 0
let of_buffer current =
{current; pending = []; pending_rev = []; unread = current.len}
let of_bytes buffer =
let len = Bytes.length buffer in
of_buffer {buffer; ofs = 0; len}
let empty = of_bytes (Bytes.create 0)
let push buffer stream =
{
stream with
pending_rev = buffer :: stream.pending_rev;
unread = stream.unread + Bytes.length buffer;
}
exception Need_more_data
let split buffer len =
assert (len <= buffer.len) ;
( {buffer with len},
{buffer with ofs = buffer.ofs + len; len = buffer.len - len} )
let read stream len =
if len > stream.unread then raise Need_more_data ;
if len <= stream.current.len then
let res, current = split stream.current len in
(res, {stream with current; unread = stream.unread - len})
else
let res = {buffer = Bytes.create len; ofs = 0; len} in
Bytes.blit
stream.current.buffer
stream.current.ofs
res.buffer
0
stream.current.len ;
let rec loop ofs pending_rev = function
| [] -> loop ofs [] (List.rev pending_rev)
| buffer :: pending ->
let current = {buffer; ofs = 0; len = Bytes.length buffer} in
let to_read = len - ofs in
if to_read <= current.len then (
Bytes.blit current.buffer 0 res.buffer ofs to_read ;
( res,
{
current =
{current with ofs = to_read; len = current.len - to_read};
pending;
pending_rev;
unread = stream.unread - len;
} ))
else (
Bytes.blit current.buffer 0 res.buffer ofs current.len ;
loop (ofs + current.len) pending_rev pending)
in
loop stream.current.len stream.pending_rev stream.pending
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