LFSR.java

This is the syntax highlighted version of LFSR.java from 1 Overview of
Introduction to Computer Science by Robert Sedgewick and Kevin Wayne.


/*************************************************************************
 *  Compilation:  javac LFSR.java
 *  Execution:    java LFSR N
 *  
 *  Simulate a LFSR for N steps and print results.
 *
 *  % java LFSR 54
 *  110010010011110110111001011010111001100010111111010010
 *
    OLD
 *  0100110010000001100010001011101010111100
 *
 *************************************************************************/


public class LFSR {

    public static void main(String[] args) { 
        int N = Integer.parseInt(args[0]);
        boolean b10 = false, b9 = true,  b8 = true,  b7 = false;
        boolean  b6 = true,  b5 = false, b4 = false, b3 = false;
        boolean  b2 = false, b1 = true,  b0 = false;

        for (int i = 0; i < N; i++) {
            boolean bit = b8 ^ b10; 
            b10 = b9; b9 = b8; b8 = b7; b7 = b6; b6 = b5;
            b5  = b4; b4 = b3; b3 = b2; b2 = b1; b1 = b0;
            b0 = bit;

            if (bit) System.out.print(1);
            else     System.out.print(0);
        }
        System.out.println();
    }
}