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/* |
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* Copyright (c) 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 minimalist buffer reader and writer. |
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* @see https://github.com/rochars/minibuffer |
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*/ |
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/** @module minibuffer */ |
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import {unpack, packTo, unpackString, packStringTo} from 'byte-data'; |
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/** |
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* @type {string} |
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* @private |
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*/ |
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const RANGE_EROR = "Range error"; |
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/** |
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* A class to read and write to buffers. |
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*/ |
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export default class MiniBuffer { |
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constructor() { |
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/** |
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* @type {number} |
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*/ |
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this.head = 0; |
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} |
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/** |
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* Set the MiniBuffer head to zero. |
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*/ |
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clear() { |
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this.head = 0; |
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} |
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/** |
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* Read a number from a buffer. |
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* @param {!Uint8Array} buffer The buffer. |
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* @param {!Object} typeDefinition The type definition. |
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* @param {?number=} index The index to read. |
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* @return {number|undefined} The number. |
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* @throws {Error} If word size + index > buffer.length |
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*/ |
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read(buffer, typeDefinition, index=null) { |
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index = index === null ? this.head : index; |
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/** @type {number} */ |
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let size = typeDefinition.bits / 8; |
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if (index + size > buffer.length) { |
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throw new Error(RANGE_EROR); |
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} |
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/** @type {number|undefined} */ |
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let num = unpack(buffer, typeDefinition, index); |
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this.head = size + index; |
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return num; |
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} |
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/** |
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* Write a number to a buffer. |
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* @param {!Uint8Array} buffer The buffer. |
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* @param {!Object} typeDefinition The type definition. |
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* @param {number} num The number to write. |
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* @param {?number=} index The buffer index to write. |
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* @throws {Error} If word size + index > buffer.length |
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*/ |
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write(buffer, typeDefinition, num, index=null) { |
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index = index === null ? this.head : index; |
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/** @type {number} */ |
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let size = typeDefinition.bits / 8; |
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if (index + size > buffer.length) { |
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throw new Error(RANGE_EROR); |
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} |
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this.head = packTo(num, typeDefinition, buffer, index); |
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} |
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/** |
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* Read a UTF-8 string from a buffer. |
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* @param {!Uint8Array} buffer The buffer. |
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* @param {number} size the max size of the string. |
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* @param {?number=} index The buffer index to read. |
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* @return {string} The string. |
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* @throws {Error} If size + index > buffer.length |
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*/ |
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readStr(buffer, size, index=null) { |
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index = index === null ? this.head : index; |
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size = index + size; |
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if (size > buffer.length) { |
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throw new Error(RANGE_EROR); |
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} |
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/** @type {string} */ |
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let str = ''; |
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for (; index<size; index++) { |
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str += unpackString(buffer, index, 1); |
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} |
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this.head = index; |
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return str; |
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} |
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/** |
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* Write a UTF-8 string to a buffer. If the string is smaller |
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* than the max size the output buffer is filled with 0s. |
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* @param {!Uint8Array} buffer The buffer. |
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* @param {string} str The string to be written as bytes. |
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* @param {number=} size The size of the string. |
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* @param {?number=} index The buffer index to write. |
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* @throws {Error} If size + index > buffer.length |
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*/ |
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writeStr(buffer, str, size=str.length, index=null) { |
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index = index === null ? this.head : index; |
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/** @type {number} */ |
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let limit = index + size; |
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if (limit > buffer.length) { |
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throw new Error(RANGE_EROR); |
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} |
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this.head = packStringTo(str, buffer, index); |
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if (this.head < index + size) { |
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for (; this.head<limit; this.head++) { |
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buffer[this.head] = 0; |
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} |
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} |
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} |
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} |
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