83 lines
2.0 KiB
JavaScript
83 lines
2.0 KiB
JavaScript
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/**
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* @author n1474335 [n1474335@gmail.com]
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* @copyright Crown Copyright 2016
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* @license Apache-2.0
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*/
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import Operation from "../Operation";
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/**
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* Bit shift right operation
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*/
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class BitShiftRight extends Operation {
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/**
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* BitShiftRight constructor
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*/
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constructor() {
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super();
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this.name = "Bit shift right";
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this.module = "Default";
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this.description = "Shifts the bits in each byte towards the right by the specified amount.<br><br><i>Logical shifts</i> replace the leftmost bits with zeros.<br><i>Arithmetic shifts</i> preserve the most significant bit (MSB) of the original byte keeping the sign the same (positive or negative).";
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this.inputType = "byteArray";
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this.outputType = "byteArray";
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this.args = [
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{
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"name": "Amount",
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"type": "number",
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"value": 1
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},
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{
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"name": "Type",
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"type": "option",
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"value": ["Logical shift", "Arithmetic shift"]
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}
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];
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}
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/**
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* @param {byteArray} input
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* @param {Object[]} args
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* @returns {byteArray}
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*/
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run(input, args) {
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const amount = args[0],
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type = args[1],
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mask = type === "Logical shift" ? 0 : 0x80;
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return input.map(b => {
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return (b >>> amount) ^ (b & mask);
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});
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}
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/**
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* Highlight Bit shift right
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*
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* @param {Object[]} pos
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* @param {number} pos[].start
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* @param {number} pos[].end
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* @param {Object[]} args
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* @returns {Object[]} pos
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*/
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highlight(pos, args) {
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return pos;
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}
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/**
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* Highlight Bit shift right in reverse
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*
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* @param {Object[]} pos
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* @param {number} pos[].start
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* @param {number} pos[].end
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* @param {Object[]} args
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* @returns {Object[]} pos
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*/
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highlightReverse(pos, args) {
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return pos;
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}
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}
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export default BitShiftRight;
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