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/** |
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* from-bytes: Numbers and strings from bytes. |
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* Copyright (c) 2017 Rafael da Silva Rocha. |
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* https://github.com/rochars/byte-data |
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*/ |
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const helpers = require("../src/helpers.js"); |
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/** |
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* Turn a byte buffer into what the bytes represent. |
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* @param {!Array<number>|!Array<string>|Uint8Array} buffer An array of bytes. |
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* @param {Object} type One of the available types. |
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* @return {!Array<number>|number|string} |
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*/ |
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function fromBytes(buffer, type) { |
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helpers.fixFloat16Endianness(buffer, type); |
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helpers.makeBigEndian(buffer, type); |
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bytesFromBase(buffer, type.base); |
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let values = readBytes( |
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buffer, |
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type |
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); |
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if (type.single) { |
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values = getSingleValue(values, type); |
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} |
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return values; |
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} |
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/** |
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* Return the first value from the result value array. |
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* @param {!Array<number>|string} values The values. |
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* @param {Object} type One of the available types. |
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* @return {number|string} |
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*/ |
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function getSingleValue(values, type) { |
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if (type.char) { |
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values = values.slice(0, type.bits / 8); |
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} else { |
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values = values[0]; |
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} |
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return values; |
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} |
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/** |
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* Turn a array of bytes into an array of what the bytes should represent. |
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* @param {!Array<number>|Uint8Array} bytes An array of bytes. |
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* @param {Object} type The type. |
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* @return {!Array<number>|string} |
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*/ |
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function readBytes(bytes, type) { |
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let values = []; |
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let i = 0; |
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let len = bytes.length - (type.offset - 1); |
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while (i < len) { |
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values.push( |
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type.sign(type.reader(bytes, i, type)) |
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); |
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i += type.offset; |
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} |
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if (type.char) { |
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values = values.join(""); |
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} |
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return values; |
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} |
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/** |
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* Turn bytes to base 10. |
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* @param {!Array<number>|Uint8Array} bytes The bytes as binary or hex strings. |
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* @param {number} base The base. |
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*/ |
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function bytesFromBase(bytes, base) { |
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if (base != 10) { |
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let i = 0; |
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let len = bytes.length; |
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while(i < len) { |
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bytes[i] = parseInt(bytes[i], base); |
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i++; |
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} |
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} |
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} |
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/** |
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* Turn numbers and strings to bytes. |
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* @param {!Array<number>|number|string} values The data. |
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* @param {Object} type One of the available types. |
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* @return {!Array<number>|!Array<string>|Uint8Array} the data as a byte buffer. |
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*/ |
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function toBytes(values, type) { |
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let bytes = writeBytes(values, type); |
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helpers.makeBigEndian(bytes, type); |
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helpers.outputToBase(bytes, type.bits, type.base); |
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helpers.fixFloat16Endianness(bytes, type); |
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return bytes; |
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} |
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/** |
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* Write values as bytes. |
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* @param {!Array<number>|number|string} values The data. |
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* @param {Object} type One of the available types. |
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* @return {!Array<number>} the bytes. |
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*/ |
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function writeBytes(values, type) { |
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let i = 0; |
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let j = 0; |
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let len = values.length; |
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let bytes = []; |
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while (i < len) { |
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j = type.writer(bytes, type.overflow(values[i]), j); |
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i++; |
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} |
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return bytes; |
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} |
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module.exports.toBytes = toBytes; |
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module.exports.fromBytes = fromBytes; |
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rochars /
byte-data
