function [q,l,r,m]=mod2_div(a,n,b,k)
%計算二進制數的模2除法運算
%a為長度為n的被除數，b為長度為k的除數 n>k
%q為商，長度為l，r為余數，長度為m

%clear;
%clc;
%a='11111000001010100000000000000000';
%b='11000000000000101';
%n=length(a);
%k=length(b);



l=n-k+1;
m=k-1;

res=a(1:k);

for i=1:l-1
    if res(1)=='1'
        q(i)='1';
        for j=1:k
            if res(j)==b(j)
                res(j)='0';
            else
                res(j)='1';
            end
        end
        res(1:k-1)=res(2:k);
        res(k)=a(k+i);
        
    else
        q(i)='0';
        res(1:k-1)=res(2:k);
        res(k)=a(k+i);
    end
end

if res(1)=='1'
    q(l)='1';
    for j=1:k
        if res(j)==b(j)
            res(j)='0';
        else
            res(j)='1';
        end
    end
    r=res(2:k);
else
    q(l)='0';
    r=res(2:k);
end