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210 ira 1 
/*******************************************************************************
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 * File: P2_EncDec.java
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 * Author: Ira W. Snyder (devel@irasnyder.com)
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 * Class: CS380 - Computer Networking
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 *
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 * Assignment: Project #2
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 * Date Last Modified: 2006-02-04
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 *
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 * Purpose: Encode / Decode a number to / from 4B5B Encoding.
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 *
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 ******************************************************************************/
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209 ira 13 
import java.io.*;
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import java.util.*;
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public class P2_EncDec
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{
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    /*
210 ira 19 
    private static final byte[][] encodingTable = {
209 ira 20 
        { 0x0, 0x1E },
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        { 0x1, 0x09 },
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        { 0x2, 0x14 },
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        { 0x3, 0x15 },
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        { 0x4, 0x0A },
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        { 0x5, 0x0B },
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        { 0x6, 0x0E },
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        { 0x7, 0x0F },
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        { 0x8, 0x12 },
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        { 0x9, 0x13 },
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        { 0xA, 0x16 },
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        { 0xB, 0x17 },
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        { 0xC, 0x1A },
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        { 0xD, 0x1B },
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        { 0xE, 0x1C },
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        { 0xF, 0x1D }};
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    */
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    public static final String[][] encodingTable = {
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        { "0000", "11110" },
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        { "0001", "01001" },
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        { "0010", "10100" },
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        { "0011", "10101" },
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        { "0100", "01010" },
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        { "0101", "01011" },
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        { "0110", "01110" },
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        { "0111", "01111" },
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        { "1000", "10010" },
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        { "1001", "10011" },
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        { "1010", "10110" },
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        { "1011", "10111" },
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        { "1100", "11010" },
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        { "1101", "11011" },
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        { "1110", "11100" },
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        { "1111", "11101" }};
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210 ira 57 
    /**
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     * Method: convert4B()
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     * Purpose: Convert a number from it's 4B representation to the
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     * corresponding 5B representation.
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     */
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    public static String convert4B (String _4BNum)
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    {
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        int i = encodingTable.length - 1;
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        for (; i >= 0; i--)
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            if (encodingTable[i][0].equals(_4BNum))
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                return encodingTable[i][1];
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        throw new IllegalArgumentException();
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    }
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210 ira 73 
    /**
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     * Method: convert5B()
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     * Purpose: Convert a number from it's 5B representation to the
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     * corresponding 4B representation.
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     */
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    public static String convert5B (String _5BNum)
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    {
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        int i = encodingTable.length - 1;
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        for (; i>=0; i--)
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            if (encodingTable[i][1].equals(_5BNum))
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                return encodingTable[i][0];
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        throw new IllegalArgumentException();
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    }
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}
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