function x = huff2mat(y)
%HUFF2MAT decodes a Huffman encoded matrix
% X = HUFF2MAT(Y) decodes a Huffman encoded structure Y with uint16 fields:
%   Y.min          The minimum value of X plus 32768
%   Y.size         The size of X
%   Y.hist         The histogram of X
%   Y.code         Huffman code
%
% The output X is of class double
%
%   See also MAT2HUFF, HUFFMAN

if ~isstruct(y) | ~isfield(y,'min') | ~isfield(y,'size') | ...
        ~isfield(y,'hist') | ~isfield(y,'code') 
    error('The input must be a structure as returned by MAT2HUFF');
end

% Initialize variables to construct x
sz = double(y.size); m = sz(1); n = sz(2);
xmin = double(y.min)-32768;         % Get X minimum
% xmin = double(y.min);         % Get X minimum
map = huffman(double(y.hist));      % Get Huffman code woords

% Create a binary search table for the Huffman decoding process. 
% 'code' contains source symbol strings corresponding to 'link' nodes,
% while 'link' contains the addresses (+) to node pairs for node
% symbol strings plus '0' and '1' or addresses (-) to decoded
% Huffman codewords in 'map'. Array 'left' is a list of nodes yet to
% be processed for 'link' entries

code = cellstr(char('','0','1'));   % Set starting conditions as
link = [2; 0; 0]; left = [2 3];     % 3 nodes w/2 unprocessed
found = 0; tofind = length(map);     % tracking variables

while length(left)&(found < tofind)
    look = find(strcmp(map,code{left(1)})); % Is stribg in map?
    if look                                 % Yes 
        link(left(1)) = -look;              % Point to Huffman map
        left = left(2:end);                 % Delete current node
        found = found + 1;                  % Increment codes found
    else                                    % No, add 2 nodes & pointers
        len = length(code);                 % Put pointers in node
        link(left(1)) = len+1;
        link = [link; 0; 0];                % Add uncompressed nodes
        code{end +1} = strcat(code{left(1)},'0');
        code{end +1} = strcat(code{left(1)},'1');
        left = left(2:end);                 % Removed processed node
        left = [left len+1 len+2];          % Add 2 unprocessed nodes
    end
end
x = unravel(y.code', link, m*n);            % Decode using C 'unravel'
x = x + xmin - 1;                           % X minimum offset adjust
x = reshape(x,m,n);                         % Make vector an array
% x = uint8(reshape(x,m,n));                         % Make vector an array