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GeezerVison is showing github.com — Java/Others/CRCAlgorithm.java at master · feiteng/Java Expand file tree/ Copy pathCRCAlgorithm.javaMore file actions 203 lines (179 loc) · 6.29 KB / Copy pathCRCAlgorithm.javaFile metadata and controls203 lines (179 loc) · 6.29 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 package Others; import java.util.ArrayList; import java.util.Random; import java.util.concurrent.ThreadLocalRandom; /** * @author dimgrichr */ public class CRCAlgorithm { private int correctMess; private int wrongMess; private int wrongMessCaught; private int wrongMessNotCaught; private int messSize; private double ber; private boolean messageChanged; private ArrayList<Integer> message; private ArrayList<Integer> dividedMessage; private ArrayList<Integer> p; private Random randomGenerator; /** * The algorithm's main constructor. * The most significant variables, used in the algorithm, * are set in their initial values. * * @param str The binary number P, in a string form, which is used by the CRC algorithm * @param size The size of every transmitted message * @param ber The Bit Error Rate */ public CRCAlgorithm(String str, int size, double ber) { messageChanged = false; message = new ArrayList<>(); messSize = size; dividedMessage = new ArrayList<>(); p = new ArrayList<>(); for (int i = 0; i < str.length(); i++) { p.add(Character.getNumericValue(str.charAt(i))); } randomGenerator = new Random(); correctMess = 0; wrongMess = 0; wrongMessCaught = 0; wrongMessNotCaught = 0; this.ber = ber; } /** * Returns the counter wrongMess * * @return wrongMess, the number of Wrong Messages */ public int getWrongMess() { return wrongMess; } /** * Returns the counter wrongMessCaught * * @return wrongMessCaught, the number of wrong messages, which are caught by the CRC algoriithm */ public int getWrongMessCaught() { return wrongMessCaught; } /** * Returns the counter wrongMessNotCaught * * @return wrongMessNotCaught, the number of wrong messages, which are not caught by the CRC algorithm */ public int getWrongMessNotCaught() { return wrongMessNotCaught; } /** * Returns the counter correctMess * * @return correctMess, the number of the Correct Messages */ public int getCorrectMess() { return correctMess; } /** * Resets some of the object's values, used on the main function, * so that it can be re-used, in order not to waste too much memory and time, * by creating new objects. */ public void refactor() { messageChanged = false; message = new ArrayList<>(); dividedMessage = new ArrayList<>(); } /** * Random messages, consisted of 0's and 1's, * are generated, so that they can later be transmitted */ public void generateRandomMess() { for (int i = 0; i < messSize; i++) { int x = ThreadLocalRandom.current().nextInt(0, 2); message.add(x); } } /** * The most significant part of the CRC algorithm. * The message is divided by P, so the dividedMessage ArrayList<Integer> is created. * If check == true, the dividedMessaage is examined, in order to see if it contains any 1's. * If it does, the message is considered to be wrong by the receiver,so the variable wrongMessCaught changes. * If it does not, it is accepted, so one of the variables correctMess, wrongMessNotCaught, changes. * If check == false, the diviided Message is added at the end of the ArrayList<integer> message. * * @param check the variable used to determine, if the message is going to be checked from the receiver * if true, it is checked * otherwise, it is not */ public void divideMessageWithP(boolean check) { ArrayList<Integer> x = new ArrayList<>(); ArrayList<Integer> k = (ArrayList<Integer>) message.clone(); if (!check) { for (int i = 0; i < p.size() - 1; i++) { k.add(0); } } while (!k.isEmpty()) { while (x.size() < p.size() && !k.isEmpty()) { x.add(k.get(0)); k.remove(0); } if (x.size() == p.size()) { for (int i = 0; i < p.size(); i++) { if (x.get(i) == p.get(i)) { x.set(i, 0); } else { x.set(i, 1); } } for (int i = 0; i < x.size() && x.get(i) != 1; i++) { x.remove(0); } } } dividedMessage = (ArrayList<Integer>) x.clone(); if (!check) { for (int z : dividedMessage) { message.add(z); } } else { if (dividedMessage.contains(1) && messageChanged) { wrongMessCaught++; } else if (!dividedMessage.contains(1) && messageChanged) { wrongMessNotCaught++; } else if (!messageChanged) { correctMess++; } } } /** * Once the message is transmitted, some of it's elements, * is possible to change from 1 to 0, or from 0 to 1, * because of the Bit Error Rate (ber). * For every element of the message, a random double number is created. * If that number is smaller than ber, then the spesific element changes. * On the other hand, if it's bigger than ber, it does not. * Based on these changes. the boolean variable messageChanged, gets the value: * true, or false. */ public void changeMess() { for (int y : message) { double x = randomGenerator.nextDouble(); while (x < 0.0000 || x > 1.00000) { x = randomGenerator.nextDouble(); } if (x < ber) { messageChanged = true; if (y == 1) { message.set(message.indexOf(y), 0); } else { message.set(message.indexOf(y), 1); } } } if (messageChanged) { wrongMess++; } } } |
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