cyclic redundancy check MATLAB implementation

crc.m

function CRC = mod2 (word, G)
    m = zeros (1,length(G));
    wordext = [word m];
    while length (G) <= length (wordext)
        
        for i = 1:length(G)
        wordext(i) = xor(wordext(i),G(i));
        end 
        
         while wordext(1) == 0
         wordext = wordext(2:end);
         if not (wordext)
             wordext = 0;
             break
         end
        end
    end
    CRC = [zeros(1:length(G)-length(wordext)) wordext];
end