[#927] added parity bit operation (#1036)

src/core/config/Categories.json

@@ -465,7 +465,8 @@
             "Luhn Checksum",
             "CRC Checksum",
             "TCP/IP Checksum",
-            "XOR Checksum"
+            "XOR Checksum",
+            "Parity Bit"
         ]
     },
     {

src/core/lib/ParityBit.mjs

@@ -0,0 +1,50 @@
+/**
+ * Parity Bit functions.
+ *
+ * @author j83305 [awz22@protonmail.com]
+ * @copyright Crown Copyright 2020
+ * @license Apache-2.0
+ *
+ */
+
+import OperationError from "../errors/OperationError.mjs";
+
+/**
+ * Function to take the user input and encode using the given arguments
+ * @param input string of binary
+ * @param args array
+ */
+export function calculateParityBit(input, args) {
+    let count1s = 0;
+    for (let i = 0; i < input.length; i++) {
+        const character = input.charAt(i);
+        if (character === "1") {
+            count1s++;
+        } else if (character !== args[3] && character !== "0" && character !== " ") {
+            throw new OperationError("unexpected character encountered: \"" + character + "\"");
+        }
+    }
+    let parityBit = "1";
+    const flipflop = args[0] === "Even Parity" ? 0 : 1;
+    if (count1s % 2 === flipflop) {
+        parityBit = "0";
+    }
+    if (args[1] === "End") {
+        return input + parityBit;
+    } else {
+        return parityBit + input;
+    }
+}
+
+/**
+ * just removes the parity bit to return the original data
+ * @param input string of binary, encoded
+ * @param args array
+ */
+export function decodeParityBit(input, args) {
+    if (args[1] === "End") {
+        return input.slice(0, -1);
+    } else {
+        return input.slice(1);
+    }
+}

src/core/operations/ParityBit.mjs

@@ -0,0 +1,128 @@
+/**
+ * @author j83305 [awz22@protonmail.com]
+ * @copyright Crown Copyright 2020
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import { calculateParityBit, decodeParityBit } from "../lib/ParityBit.mjs";
+
+/**
+ * Parity Bit operation
+ */
+class ParityBit extends Operation {
+
+    /**
+     * ParityBit constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Parity Bit";
+        this.module = "Default";
+        this.description = "A parity bit, or check bit, is the simplest form of error detection. It is a bit which is added to a string of bits and represents if the number of 1's in the binary string is an even number or odd number.<br><br>If a delimiter is specified, the parity bit calculation will be performed on each 'block' of the input data, where the blocks are created by slicing the input at each occurence of the delimiter character";
+        this.infoURL = "https://wikipedia.org/wiki/Parity_bit";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Mode",
+                type: "option",
+                value: [
+                    "Even Parity",
+                    "Odd Parity"
+                ]
+            },
+            {
+                name: "Postion",
+                type: "option",
+                value: [
+                    "Start",
+                    "End"
+                ]
+            },
+            {
+                name: "Encode or Decode",
+                type: "option",
+                value: [
+                    "Encode",
+                    "Decode"
+                ]
+            },
+            {
+                name: "Delimiter",
+                type: "shortString",
+                value: ""
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        if (input.length === 0) {
+            return input;
+        }
+        /**
+         * determines weather to use the encode or decode method based off args[2]
+         * @param input input to be encoded or decoded
+         * @param args array
+         */
+        const method = (input, args) => args[2] === "Encode" ? calculateParityBit(input, args) : decodeParityBit(input, args);
+        if (args[3].length > 0) {
+            const byteStrings = input.split(args[3]);
+            for (let byteStringsArrayIndex = 0; byteStringsArrayIndex < byteStrings.length; byteStringsArrayIndex++) {
+                byteStrings[byteStringsArrayIndex] = method(byteStrings[byteStringsArrayIndex], args);
+            }
+            return byteStrings.join(args[3]);
+        }
+        return method(input, args);
+    }
+
+    /**
+     * Highlight Parity Bit
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlight(pos, args) {
+        if (args[3].length === 0) {
+            if (args[1] === "Prepend") {
+                pos[0].start += 1;
+                pos[0].end += 1;
+            }
+            return pos;
+        }
+        // need to be able to read input to do the highlighting when there is a delimiter
+    }
+
+    /**
+     * Highlight Parity Bit in reverse
+     *
+     * @param {Object[]} pos
+     * @param {number} pos[].start
+     * @param {number} pos[].end
+     * @param {Object[]} args
+     * @returns {Object[]} pos
+     */
+    highlightReverse(pos, args) {
+        if (args[3].length === 0) {
+            if (args[1] === "Prepend") {
+                if (pos[0].start > 0) {
+                    pos[0].start -= 1;
+                }
+                pos[0].end -= 1;
+            }
+            return pos;
+        }
+    }
+
+}
+
+export default ParityBit;