Animations using java

REMINDER: Ms. Newman should be coming to PHS after school

1. Simulate one step. The step() method simulates one step of the LFSR and returns the rightmost bit as an integer (0 or 1). For example,

// LFSR lfsr1 = new LFSR("01101000010", 9);
// for this assignment the seed and tap can be hardcoded or input
String lfsr1 = "01101000010";
int tap = 9;
StdOut.println(lfsr1);
for (int i = 0; i < 10; i++) {
    // int bit = lfsr1.step();
    // code to create a sequence of 0s and 1s like the example below
    StdOut.println(lfsr1 + " " + bit);
}

outputs
01101000010
11010000101 1
10100001011 1
01000010110 0
10000101100 0
00001011001 1
00010110010 0
00101100100 0
01011001001 1
10110010010 0
01100100100 0

1. Extracting multiple bits. The method generate() takes a positive integer k as an argument and returns a k-bit integer obtained by simulating k steps of the LFSR. This task is easy to accomplish with a little arithmetic:

• initialize a variable to zero
• for each bit extracted, double the variable
• add the bit returned by step()

For example, extracting (from left to right) each bit from the sequence 1 1 0 0 1, the variable takes on the values 1, 3, 6, 12, and 25, ending with the binary representation of the bit sequence.

gen = 0
gen = gen * 2 + new_bit = 0 * 2 + 1 = 1
gen = gen * 2 + new_bit = 1 * 2 + 1 = 3
gen = gen * 2 + new_bit = 3 * 2 + 0 = 6
gen = gen * 2 + new_bit = 6 * 2 + 0 = 12
gen = gen * 2 + new_bit = 12 * 2 + 1 = 25

For example,

// LFSR lfsr2 = new LFSR("01101000010", 9); 
// for this assignment the seed and tap can be hardcoded or input
String lfsr2 = "01101000010";
int tap = 9;
StdOut.println(lfsr2);
for (int i = 0; i < 10; i++) {
    // int r = lfsr2.generate(5);
    // code to generate a number like 25 in the example above
    StdOut.println(lfsr2 + " " + r);
}

outputs
01101000010
00001011001 25
01100100100 4
10010011110 30
01111011011 27
01101110010 18
11001011010 26
01101011100 28
01110011000 24
01100010111 23
01011111101 29

Classwork:
Write a java program, YI_LFSRSim.java to generate an output like the one right above for a given seed.
NOTE: It doesn’t have to be OOP.