Scrambler design not working

Hi i have code for a randomizer/scrambler & de-randomizer/de-scrambler but I am getting weird results as I tried simply preforming modulus 2 addition (XOR) with my polynomial but once I de-scramble it 3 bits seem to be wrong. To generate my 2 byte input sequence I just used seq=rand(1,16); seq=seq>0.5; scrambled=scrambler(seq) descrambled=descrambler(scrambled)

For me its always showing errors in the first 8 bits and the rest are fine, I don't know if this is a result of the process im using or just a coincidence.

% Scrambler: used to prevent spectral lines from forming in bit  if true
% Sequence.
% Input:
%   data: Bit sequence (2 bytes long)
%   poly: randomizer polynomial (set to 16 bit as defualt)
%   taps= 16,15,13,4 (defualt)
% Output: 2 byte (16 bit) scrambled binary sequence
function scrambled=scrambler(varargin)
% Defualt polynomial=[16 15 0 13 0 0 0 0 0 0 0 0 4 0 0 0];
if isempty(varargin)
    fprintf('Please enter Input');
end
data=varargin{1};
if (length(varargin)>1)
    polyn=varargin(2);
end
if (length(varargin)==1|isempty(polyn))
    polyn=[1 1 0 1 0 0 0 0 0 0 0 0 1 0 0 0];
end
D=data'; % To use circshift we need a vector.

for i=1:length(data) % all the data 1 circulation through LFSR
    if (i~=1) % Dont rotate vector on 1st try
        data=circshift(data,1);
    end
    last=length(data);
    % XOR Operations based on randomizer polynomial
    for j=1: length(D)
        if (polyn(j)==1&&j>1)
            D(i)=xor(D(i),D(last));
            last=j;
        end
    end
end
scrambled=D';
end

    % Descrambler: used to de-randomize the binary sequence.
    function descrambled=descrambler(varargin)
    % Defualt polynomial=[16 15 0 13 0 0 0 0 0 0 0 0 4 0 0 0];
    if isempty(varargin)
        fprintf('Please enter Input');
    end
    scrambled=varargin{1};
    if (length(varargin)>1)
        polyn=varargin(2);
    end
    if (length(varargin)==1|isempty(polyn))
        polyn=[1 1 0 1 0 0 0 0 0 0 0 0 1 0 0 0];
    end
    D=scrambled'; % To use circshift we need a vector.

    for i=1:length(scrambled) % all the data 1 circulation through LFSR
        if (i~=1) % Dont rotate vector on 1st try
           scrambled=circshift(scrambled,1);
        end
        last=length(scrambled);
        % XNOR Operations based on randomizer polynomial
        for j=1: length(D)
            if (polyn(j)==1&&j>1)
                D(i)=~xor(D(i),D(last));
                last=j;
            end
        end
    end
    descrambled=D';
    end

Answer 1

[RGR]

I forget what the solution was but I made a new scrambler which works code below:

if true
  % code
% Scrambler: used to prevent spectral lines from forming in bit
% Sequence. [0 0 1 1] LFSR
function scrambled=scrambler(data)
% Initialize variables:
scrambled=[];
count=1;
% Set r1 and r2 initial values:
r1=0;r2=0;
% Cycle the data through the registers:
for i=1:length(data) % all the data 1 circulation through LFSR
% First two registers Pass all the data:
if (count==1)
    r1=data(i);
    result=r1;
end
if (count==2)
    r2=data(i);
    result=r2;
end
% Last two registers scramble data by xoring them
% with value of first two registers:
if (count==3)
    r3=data(i);
    result=xor(r3,r1);
end
if (count==4)
    r4=data(i);
    result=xor(r4,r2);
end
% Fill data in accumulator array:
scrambled=[scrambled result];
% Reset Counter:
if (count==4)
    count=1;
else
    count=count+1;
end
end
end