% Script file: fcsr.m
%
% Purpose:an algorithm to achieve the peseudorandom sequence with the size of T=12 by
% FCSR block
%
%
% Record of revisions:
% ==== ========== =====================
% 05/20/07 Xin Li Original code
% Define variables:
% msinteger --state integer of mainregister
% csinteger --state integer of carries register
% rnd --the output sequence of the fcsr cipher
% k --Main register size
% q --Connection integer
% d --
% T --the period of the output sequence
% mkey --the key sequence for the main register
% ckey --the key sequence for the carries register
% m_register --the main register matrix
% cell --the carries register matrix
% F --the filter function
% S --the output sequence
function [msinteger,csinteger,rnd]=fcsr
k=3;
T=12;
q=-13;
d=[0 1 1 1];% d=(abs(q)+1)/2.
F=d;
mkey=[zeros(1,3) 1];% key.
m_register = mkey;%The main register is initialized with the key K.
newregister=zeros(1,4);
newcell=zeros(1,4);
cell=zeros(1,4);% Carries register is initialized to 0.
%cell=ckey;
msinteger=zeros(1,T);
csinteger=zeros(1,T);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% The output sequence--rnd of the FCSR%
% the mainregister's state integer--mregister and
%carries rigister's state integer--cregister of the FCSR%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for i=1:T
rnd(i)=m_register(4);
for l=2:4
msinteger(i)=msinteger(i)+m_register(l)*2.^(4-l);
end
for l=2:4
csinteger(i)=csinteger(i)+cell(l)*2.^(4-l);
end
for j=2:4
newregister(j)=xor(xor(m_register(j-1),d(j)*cell(j)),d(j)*m_register(4));
newcell(j)=xor(xor(m_register(j-1)*cell(j),cell(j)*m_register(4)),m_register(j-1)*m_register(4));
end
m_register= newregister;
cell=newcell;
cell(2)=0;
end
%rnd=[m_register cell];
% m_register=mkey=[0 0 1],
%cell=ckey=[0 0 0]
