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lfsr.py
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/
lfsr.py
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#!/usr/bin/env python
class GaloisLFSR:
# 16-bit
def __init__(self, seed):
self.state = seed & 0xFFFF
def getRand(self):
self.state = (self.state >> 1) ^ (-(self.state&0x01) & 0xB400)
return self.state & 0x01
class FibonacciLFSR:
# 16-bit
def __init__(self, seed):
self.state = seed & 0xFFFF
def getRand(self):
bit = ((self.state >> 0) ^ (self.state >> 2) ^ (self.state >> 3) ^ (self.state >> 5)) & 0x01
self.state = ((self.state >> 1) | (bit<<15)) & 0xFFFF
return self.state & 0x01
if __name__ == "__main__":
# Test galois lfsr
glfsr = GaloisLFSR(0xACE1)
glfsr.getRand()
assert(0xE270 == glfsr.state)
print "Galois LFSR test passed."
# Test fibonacci lfsr
flfsr = FibonacciLFSR(0xACE1)
flfsr.getRand()
assert(0x5670 == flfsr.state)
print "Fibonacci LFSR test passed."