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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 Sserialize and deserialize integers and floats. |
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* @see https://github.com/rochars/byte-data |
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*/ |
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import { IEEE754Buffer } from 'ieee754-buffer'; |
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import { TwosComplementBuffer } from 'twos-complement-buffer'; |
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import { UintBuffer } from 'uint-buffer'; |
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/** |
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* A class to pack and unpack integers and floating-point numbers. |
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* Signed integers are two's complement. |
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* Floating-point numbers are IEEE 754 standard. |
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*/ |
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export default class NumberBuffer { |
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/** |
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* Read one number from a byte buffer. |
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* @param {number} bits The number of bits of the number. |
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* @param {boolean} fp Tue for floating-point numbers. |
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* @param {boolean} signed True for signed numbers. |
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* @throws {Error} If the type definition is not valid. |
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*/ |
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constructor(bits, fp, signed) { |
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/** @type {TwosComplementBuffer|UintBuffer|IEEE754Buffer} */ |
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let parser; |
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if (fp) { |
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validateFloatType(bits); |
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parser = this.getFPParser_(bits); |
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} else { |
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validateIntType(bits); |
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parser = signed ? new TwosComplementBuffer(bits) : new UintBuffer(bits); |
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} |
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/** @type {TwosComplementBuffer|UintBuffer|IEEE754Buffer} */ |
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this.parser = parser; |
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/** @type {number} */ |
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this.offset = Math.ceil(bits / 8); |
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} |
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/** |
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* Read one number from a byte buffer. |
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* @param {!Uint8Array|!Array<number>} buffer An array of bytes. |
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* @param {number=} index The index to read. |
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* @return {number} The number. |
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* @throws {Error} On overflow. |
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*/ |
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unpack(buffer, index=0) { |
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return this.parser.unpack(buffer, index); |
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} |
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/** |
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* Write one number to a byte buffer. |
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* @param {!Uint8Array|!Array<number>} buffer An array of bytes. |
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* @param {number} num The number. |
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* @param {number=} index The index being written in the byte buffer. |
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* @return {number} The next index to write on the byte buffer. |
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* @throws {Error} If num is NaN. |
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* @throws {Error} On overflow. |
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*/ |
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pack(buffer, num, index=0) { |
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return this.parser.pack(buffer, num, index); |
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} |
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/** |
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* Return a instance of IEEE754Buffer. |
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* @param {number} bits The number of bits. |
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* @return {IEEE754Buffer} |
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* @private |
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*/ |
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getFPParser_(bits) { |
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if (bits === 16) { |
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return new IEEE754Buffer(5, 11); |
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} else if(bits === 32) { |
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return new IEEE754Buffer(8, 23); |
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} else { |
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return new IEEE754Buffer(11, 52); |
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} |
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} |
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} |
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/** |
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* @type {string} The type definition error message. |
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* @private |
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*/ |
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const TYPE_ERR = 'Unsupported type'; |
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/** |
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* Validate the type definition of floating-point numbers. |
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* @param {number} bits The number of bits. |
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* @throws {Error} If the type definition is not valid. |
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* @private |
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*/ |
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function validateFloatType(bits) { |
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if (!bits || bits !== 16 && bits !== 32 && bits !== 64) { |
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throw new Error(TYPE_ERR + ': float, bits: ' + bits); |
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} |
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} |
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/** |
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* Validate the type definition of integers. |
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* @param {number} bits The number of bits. |
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* @throws {Error} If the type definition is not valid. |
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* @private |
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*/ |
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function validateIntType(bits) { |
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if (!bits || bits < 1 || bits > 53) { |
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throw new Error(TYPE_ERR + ': int, bits: ' + bits); |
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} |
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} |
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|
rochars /
byte-data
