hades.utils
Class LFSR32

java.lang.Object
  hades.utils.LFSR32

public class LFSR32

extends java.lang.Object

a 32-bit linear feedback shift register based on the (31 3 0) polynom. This class provides all methods to realize LFSR-based pseudorandom pattern generators and signature analyzers. The polynom used in this class is "hardcoded" and cannot be changed easily.

Constructor Summary

LFSR32()

Method Summary

void	clock() calculate the next state of the LFSR32 register.
int	getValue()
static void	main(java.lang.String[] argv) simple LFSR32 selftest.
static void	msg(java.lang.String s) print the specified string to stdout
void	normal_clock() calculate a new value for this LFSR32, based on the "normal" hardware solution with individual XOR taps.
void	setValue(int value)
void	signature_clock(int input_value) calculate a new value for this LFSR32, based on the "normal" clock method with individual XOR taps.
static void	usage() print the usage message

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LFSR32

public LFSR32()

Method Detail

setValue

public void setValue(int value)

getValue

public int getValue()

clock

public void clock()

calculate the next state of the LFSR32 register. We use the "software" realization based on one parallel XOR to generate a new LFSR32 value. See Numerical Recipes for details of the algorithm.

normal_clock

public void normal_clock()

calculate a new value for this LFSR32, based on the "normal" hardware solution with individual XOR taps. As our polynom has just 3 taps, this is quite fast.

signature_clock

public void signature_clock(int input_value)

calculate a new value for this LFSR32, based on the "normal" clock method with individual XOR taps. However, we first do a parallel XOR with input_value for signature analysis.

msg

public static void msg(java.lang.String s)

print the specified string to stdout

usage

public static void usage()

print the usage message

main

public static void main(java.lang.String[] argv)

simple LFSR32 selftest.