function [retval] = fd3(fid)
% [retval] = fd3(fid)
% read a 3 byte integer out of a file

%
% fread3.m
%
% Original Author: Bruce Fischl
% CVS Revision Info:
% $Author: nicks $
% $Date: 2007/01/10 22:55:09 $
% $Revision: 1.2 $
%
% Copyright (C) 2002-2007,
% The General Hospital Corporation (Boston, MA).
% All rights reserved.
%
% Distribution, usage and copying of this software is covered under the
% terms found in the License Agreement file named 'COPYING' found in the
% FreeSurfer source code root directory, and duplicated here:
% https://surfer.nmr.mgh.harvard.edu/fswiki/FreeSurferOpenSourceLicense
%
% General inquiries: freesurfer@nmr.mgh.harvard.edu
% Bug reports: analysis-bugs@nmr.mgh.harvard.edu
%

b1 = fread(fid, 1, 'uchar') ;
b2 = fread(fid, 1, 'uchar') ;
b3 = fread(fid, 1, 'uchar') ;
retval = bitshift(b1, 16) + bitshift(b2,8) + b3 ;