I am executing the code below for run length encoding, how to make code for inverse Run Length encoding to get the decompressed image?

my code for RLE is
function  y = estring(str)
len = numel(str); %65536
i = 0;
count = zeros(1,len);
y=[];
while( i<len )
  j=0;
  count(i+1) = 1;
  while( true )
      j = j + 1;
      if( i+j+1 > len )
          break;
      end
      if( str(i+j+1)==str(i+1) )
          count(i+1) = count(i+1) + 1;
      else
          break;
      end
  end
    if( count(i+1)==1 )
        a=str(i+1);
        length(a);
        y = [y a];
        i = i + 1;
    else
        a=str(i+1);
        b=count(i+1);
        y =[y a b];
        i = i + b;
    end
end
end

I want inverse of it, for IRLE, can anyone help me in this