Examples

Basic Examples

5-bit LFSR with feedback polynomial: x⁵+ x²+1

Default feedback polynomial is p(x) = x⁵+ x²+ 1 and default initial state is all ones

import numpy as np
from pylfsr import LFSR

L = LFSR()

# print the info
L.info()

5 bit LFSR with feedback polynomial  x^5 + x^2 + 1
Expected Period (if polynomial is primitive) =  31
Current :
State        :  [1 1 1 1 1]
Count        :  0
Output bit   : -1
feedback bit : -1

Execute cycles (run LFSR by clock)

# one cycle
L.next()

# K cycles
k=10
seq  = L.runKCycle(k)

#Cycles of a full period, #cycles = expected period of LFSR

# L.runFullCycle()  # Depreciated
seq = L.runFullPeriod()

5-bit LFSR with custom state and feedback polynomial

state = [0,0,0,1,0]
fpoly = [5,4,3,2]
L = LFSR(fpoly=fpoly,initstate =state, verbose=True)
L.info()
tempseq = L.runKCycle(10)
L.set(fpoly=[5,3])

Fibonacci LFSR

By deault, LFSR is in Fibonacci configuration mode, but it can be implicitly set to Fibonacci conf

L = LFSR(fpoly = [5,4,3,2], conf='fibonacci')
L.Viz(show_outseq=False)

Galois LFSR

To construct LSFR with Galois configuration , pass conf = ‘galois’

L = LFSR(fpoly = [5,4,3,2], conf='galois')
L.Viz(show_outseq=False)

23-bit LFSR: x²³+ x¹⁸+1

L = LFSR(fpoly=[23,18],initstate ='random',verbose=True)
L.info()
L.runKCycle(10)
L.info()
seq = L.seq

23-bit LFSR: x²³+ x⁵+1

fpoly = [23,5]
L1 = LFSR(fpoly=fpoly,initstate ='ones', verbose=False)
L1.info()

23 bit LFSR with feedback polynomial  x^23 + x^5 + 1
Expected Period (if polynomial is primitive) =  8388607
Current :
 State        :  [1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1]
 Count        :  0
 Output bit   :  -1
 feedback bit :  -1