chat/modules/ArrayBufferUtils.jsm
author Patrick Cloke <clokep@patrick.cloke.us>
Fri, 04 Oct 2019 09:32:00 +0200
changeset 36211 81233eef62edcad1e1f548e2165c33960070e3e2
parent 35696 e5737872508567abf8b0444f43eb4ee4ce211c75
child 38076 7853102282e6bc50b8a2317e86b5185b0c5c250d
permissions -rw-r--r--
Bug 1586340 - Add JetBrains IDE files to .hgignore. r=mkmelin DONTBUILD

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * JavaScript ArrayBuffers are missing a variety of useful methods which are
 * provided by this module.
 */

this.EXPORTED_SYMBOLS = [
  "copyBytes",
  "ArrayBufferToBytes",
  "BytesToArrayBuffer",
  "StringToBytes",
  "StringToArrayBuffer",
  "ArrayBufferToString",
  "ArrayBufferToHexString",
];

/*
 * aTarget / aSource are ArrayBuffers.
 *
 * Note that this is very similar to ArrayBuffer.slice except that it allows
 * for an offset in the target as well as the source.
 */
function copyBytes(
  aTarget,
  aSource,
  aTargetOffset = 0,
  aSourceOffset = 0,
  aLength = aSource.byteLength
) {
  // The rest just gets the data copied into it.
  let view = new Uint8Array(aTarget, aTargetOffset);
  view.set(new Uint8Array(aSource, aSourceOffset, aLength));
}

function ArrayBufferToBytes(aBuf) {
  return [...new Uint8Array(aBuf)];
}

function BytesToArrayBuffer(aBytes = []) {
  let buf = new ArrayBuffer(aBytes.length);
  let view = new Uint8Array(buf);
  view.set(aBytes);
  return buf;
}

function StringToBytes(aString) {
  let bytes = [];
  for (let i in aString) {
    bytes.push(aString.charCodeAt(i));
  }
  return bytes;
}

function StringToArrayBuffer(aString) {
  return BytesToArrayBuffer(StringToBytes(aString));
}

function ArrayBufferToString(aData) {
  return Array.from(new Uint8Array(aData))
    .map(b => String.fromCharCode(b))
    .join("");
}

function ArrayBufferToHexString(aData) {
  return (
    "0x" +
    Array.from(new Uint8Array(aData))
      .map(b => ("0" + b.toString(16)).slice(-2))
      .join(" ")
  );
}