append3d.m

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function resultbuf=append3d(prevbuf, nextbuf, resultsize)
% append(prevbuf, nextbuf, resultsize)
%
% Similar to the append method, but for three dimensional arrays.
% Operates in the third dimension, and both matrices must be three-dimensional.

% Toolbox for nonlinear filtering.
% Copyright (C) 2005  Jakob Ros閚 <[e-mail]>
%
% This program is free software; you can redistribute it and/or
% modify it under the terms of the GNU General Public License
% as published by the Free Software Foundation; either version 2
% of the License, or (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program; if not, write to the Free Software
% Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

if length(prevbuf)	% _slightly_ faster version of ~isempty(prevbuf) :)
	% prevbuf is not empty. append nextbuf to it.
	nextlen=size(nextbuf,3);
	prevlen=size(prevbuf,3);
	if (nextlen+prevlen>resultsize)&&(resultsize>0)
		% The result needs to be truncated to fit the size specified by resultsize
		if nextlen>=resultsize
			% If nextbuf is really big, we don't need to care about prevbuf
			% (all of it will be lost after the truncation anyway)
			% Truncate nextbuf to make it fit the buffer!
			resultbuf=nextbuf(:,:,end-resultsize+1:end);
		else
			% Append, with truncation of prevbuf!
			resultbuf=zeros(size(nextbuf,1), size(nextbuf,2),resultsize);
			resultbuf(:,:,1:resultsize-nextlen)=prevbuf(:,:,end-resultsize+nextlen+1:end);
			resultbuf(:,:,resultsize-nextlen+1:resultsize)=nextbuf;
		end
	else
		% No truncation is necessary. Just append!
		resultbuf=zeros(size(nextbuf,1), size(nextbuf,2), prevlen+nextlen);
		resultbuf(:,:,prevlen+1:prevlen+nextlen)=nextbuf;
		resultbuf(:,:,1:prevlen)=prevbuf;
	end
else
	% prevbuf was empty so no appending is necessary
	resultbuf=nextbuf;
end