huffman_ac_decoding.asv

%% this function is to do the Inverse huffman coding 
%% the input should be the whole sequence including the output 
%% AC components and EOB, the idea is to match the sequence with the code in
%% decode table, get the category of the value then cut the relative number, 
%% change them into decimal

function [ac_dehuff]=huffman_ac_decoding(blockbit_seq)
ac_dehuff=[];point=1;
len=length(blockbit_seq);

for i = point:len
    temp_ac = blockbit_seq(point:i);
    group_ac = detableAC2(temp_ac);
    
    if group_ac(1,1)==0 && group_ac(1,2)==0; % EOB reached.
       group_ac; 
       
       
       
       
       
       break
    
    elseif group_ac(1,2) >= 0 && group_ac(1,2) <= 10;%get correct output, while doing the loop the category_dc
       group_ac;                                      %would be 11
      
       for zero = 1: group_ac(1,1)
          ac_dehuff=[ac_dehuff, 0];
       end

        %ac_dehuff = [ac_dehuff zeros(1,group_ac(1,1));
      
        if group_ac(1,2)==0;
            ac_dehuff=[ac_dehuff, 0];
        else                  
         r_ac = blockbit_seq(i+1:i+group_ac(1,2));
          if r_ac(1)=='0';   %% if it's a negative number
            for j=1:length(r_ac)
                 if r_ac(j)=='0';
                     r_ac(j)='1';
                 else
                     r_ac(j)='0';
                 end
            end     
            r_new=-bin2dec(r_ac);
           else r_new=bin2dec(r_ac);
          end
          r_new;
          ac_dehuff=[ac_dehuff,r_new];
        end
     
     point=i+group_ac(1,2)+1;  
     i=point;
     
     ac_dehuff;
    end
end %finish AC part
ac_dehuff;