Mercurial > forge
view main/comm/inst/lz77deco.m @ 9666:67d4cfc5eeb3 octave-forge
comm: update license to GPLv3+
author | carandraug |
---|---|
date | Tue, 13 Mar 2012 04:31:21 +0000 |
parents | 90a46621a91d |
children |
line wrap: on
line source
## Copyright (C) 2007 Gorka Lertxundi ## ## 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 3 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, see <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {@var{m} =} lz77deco (@var{c}, @var{alph}, @var{la}, @var{n}) ## Lempel-Ziv 77 source algorithm decoding implementation. Where ## ## @table @asis ## @item @var{m} ## message decoded (1xN). ## @item @var{c} ## encoded message (Mx3). ## @item @var{alph} ## size of alphabet. ## @item @var{la} ## lookahead buffer size. ## @item @var{n} ## sliding window buffer size. ## @end table ## @seealso{lz77enco} ## @end deftypefn function m = lz77deco(c, alph, la, n) if (la <= 0 || n <= 0) error("lz77deco: Lookahead buffer size and window size must be higher than 0."); endif if n - la < la error("lz77deco: Unreachable configuration: n - la >= la."); endif if alph < 2 error("lz77deco: Alphabet size within less than 2 symbols? Is that possible?."); endif if columns(c) != 3 error("lz77deco: Encoded message must be a Nx3 matrix."); endif window = zeros(1,n); x = length(c); len = length(c); for x=1:len ## update window temp = n-la+c(x,2)-c(x,1); for y=1:temp window(n-la+y) = window(c(x,1)+y); endfor window(n-la+c(x,2)+1) = c(x,3); ## decoded message m_deco = window(n-la+1:n-la+c(x,2)+1); if x == 1 m = m_deco; else m = [m m_deco]; endif ## CCW shift temp = c(x,2)+1; window(1:n-la) = window(temp+1:n-la+temp); endfor endfunction %!demo %! lz77deco([8 2 1 ; 7 3 2 ; 6 7 2 ; 2 8 0],3,9,18)