class(fpoly=[5,2], initstate=’ones’, verbose=False)

help doc

Linear Feedback Shift Register

#Parameters ————————————

#Attributes ————————————

  • count : int
    Count the cycle
  • seq : np.array shape =(count,)
    Output sequence stored in seq since first cycle. If -1, no cycle has been excecuted, count =0
  • outbit : binary bit
    Current output bit, Last bit of current state if -1, no cycle has been excecuted, count =0
  • feedbackbit : binary bit
    If -1, no cycle has been excecuted, count =0
  • M : int
    length of LFSR, M-bit LFSR,
  • expectedPeriod : int
    Expected period of sequence if feedback polynomial is primitive and irreducible (as per reference), period will be 2^M -1
  • feedpoly : str
    feedback polynomial

#Methods ————————————

  • next()

    run one cycle on LFSR with given feedback polynomial and update the count, state, feedback bit, output bit and seq

    return: binary bit output bit : binary

  • runKCycle(k)

    run k cycles and update all the Parameters

    return tempseq : shape =(k,)

    output binary sequence of k cycles

  • runFullCycle()

    run full cycle ( = 2^M-1)

    return seq : binary output sequence since start: shape = (count,)

  • set(fpoly,state=’ones’)

    set feedback polynomial and state

    fpoly : list feedback polynomial like [5,4,3,2]

    state : np.array, like np.array([1,0,0,1,1]), default =’ones’ Initial state is intialized with ones and length of register is equal to degree of feedback polynomial if state=’rand’, initial state is intialized with random binary sequence of length equal to degree of feedback polynomial

  • reset()

    Reseting LFSR to its initial state and count to 0

  • changeFpoly(newfpoly, reset=False)

    Changing Feedback polynomial newfpoly : list like, [5,4,2,1], changing the feedback polynomial

    reset : boolean default=False if True, reset all the Parameters : count=0, seq=-1.. if False, leave the LFSR as it is only change the feedback polynomial as used in ‘Enhancement of A5/1: Using variable feedback polynomials of LFSR’ ref: 10.1109/ETNCC.2011.5958486

  • check()

    check if -degree of feedback polynomial <= length of LFSR >=1 -given intistate of LFSR is correct

  • info()

    display the information about LFSR with current state of variables

  • get_fpolyList(m=None)

    Get the list of primitive polynomials as feedback polynomials for m-bit LFSR if m is None, list of feedback polynomials for 1 < m < 32 is return as a dictionary

  • get_Ifpoly(fpoly)

    Get the image of primitive polynomial fpoly, which is also a valid primitive polynomial