/****************************************************************************** * Compilation: javac HammingEncoder.java StdIn.java * Execution: java HammingEncoder < all4.txt * * Read in sequences of 4 bits at a time from stdin, compute * 3 parity bits for Hamming code, and print resulting 7 bits * to stdout. * * ******************************************************************************/ public class HammingEncoder { // return an integer corresponding to the 4 digit hex string public static int fromHex(String s) { return Integer.parseInt(s, 16) & 0xFFFF; } public static void main(String[] args) { while (!StdIn.isEmpty()) { int m1 = fromHex(StdIn.readString()); if (m1 == 0xFFFF) break; int m2 = fromHex(StdIn.readString()); int m3 = fromHex(StdIn.readString()); int m4 = fromHex(StdIn.readString()); // compute parity bits int p1 = m1 ^ m2 ^ m4; int p2 = m1 ^ m3 ^ m4; int p3 = m2 ^ m3 ^ m4; // print results StdOut.print(m1 + " " + m2 + " " + m3 + " " + m4 + " "); StdOut.print(p1 + " " + p2 + " " + p3); StdOut.println(); } } }