66 lines
2.4 KiB
JavaScript
66 lines
2.4 KiB
JavaScript
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/*
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* Copyright (c) 2017-2018 Rafael da Silva Rocha.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*/
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/**
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* @fileoverview A function to swap endianness in byte buffers.
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* @see https://github.com/rochars/endianness
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*/
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/** @module endianness */
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/**
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* Swap the byte ordering in a buffer. The buffer is modified in place.
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* @param {!Array|!Uint8Array} bytes The bytes.
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* @param {number} offset The byte offset.
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* @param {number=} start The start index. Assumes 0.
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* @param {number=} end The end index. Assumes the buffer length.
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* @throws {Error} If the buffer length is not valid.
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*/
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export default function endianness(bytes, offset, start=0, end=bytes.length) {
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if (end % offset) {
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throw new Error("Bad buffer length.");
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}
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for (let index = start; index < end; index += offset) {
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swap(bytes, offset, index);
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}
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}
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/**
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* Swap the byte order of a value in a buffer. The buffer is modified in place.
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* @param {!Array|!Uint8Array} bytes The bytes.
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* @param {number} offset The byte offset.
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* @param {number} index The start index.
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* @private
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*/
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function swap(bytes, offset, index) {
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offset--;
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for(let x = 0; x < offset; x++) {
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/** @type {*} */
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let theByte = bytes[index + x];
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bytes[index + x] = bytes[index + offset];
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bytes[index + offset] = theByte;
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offset--;
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}
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}
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