%I、Q兩路短碼的產生
function y=shortcode(n)
codegI=[1,0,0,0,0,1,0,1,1,1,0,0,0,1,0];%生成器抽頭序列
codegQ=[1,0,0,1,1,1,1,0,0,0,1,1,1,0,0];%生成器抽頭序列
%codegQ=[0,0,0,0,1,0,1,1,1,0,0,0,1,0,1];%生成器抽頭序列
%initcode=randsrc(1,42,[0,1]);%長為42的隨機數，移位寄存器初始狀態
reginitialI=[1,0,0,0,0,0,0,0,0,0,0,0,0,0,0];%移位寄存器初始狀態
reginitialQ=[1,0,0,0,0,0,0,0,0,0,0,0,0,0,0];%移位寄存器初始狀態
regstateI=reginitialI;
regnextI=zeros(1,15);
regstateQ=reginitialQ;
regnextQ=zeros(1,15);
for numI=1:n
    codeI(1,numI)=regstateI(1,15);
    regnextI(1,1)=0;    
    regnextI(1,2:15)=regstateI(1,1:14);
    codeaddI=regstateI(1,15)*codegI;
    regstateI=mod(regnextI+codeaddI,2);
    
    codeI(2,numI)=regstateQ(1,15);
    regnextQ(1,1)=0;    
    regnextQ(1,2:15)=regstateQ(1,1:14);
    codeaddQ=regstateQ(1,15)*codegQ;
    regstateQ=mod(regnextQ+codeaddQ,2);
%下為I的互逆多項式產生的序列
%    codeI(2,numI)=regstateQ(1,15);
%    regnextQ(1,1)=mod(sum(regstateQ.*codegQ),2);    
%    regnextQ(1,2:15)=regstateQ(1,1:14);
%    regstateQ=regnextQ;
end
y=codeI;