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view main/comm/inst/rsencof.m @ 9666:67d4cfc5eeb3 octave-forge
comm: update license to GPLv3+
author | carandraug |
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date | Tue, 13 Mar 2012 04:31:21 +0000 |
parents | 2de537641f94 |
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## Copyright (C) 2003 David Bateman ## ## 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} {} rsencof (@var{in},@var{out}) ## @deftypefnx {Function File} {} rsencof (@var{in},@var{out},@var{t}) ## @deftypefnx {Function File} {} rsencof (@var{...},@var{pad}) ## ## Encodes an ascii file using a Reed-Solomon coder. The input file is ## defined by @var{in} and the result is written to the output file @var{out}. ## The type of coding to use is determined by whether the input file is 7- ## or 8-bit. If the input file is 7-bit, the default coding is [127,117]. ## while the default coding for an 8-bit file is a [255, 235]. This allows ## for 5 or 10 error characters in 127 or 255 symbols to be corrected ## respectively. The number of errors that can be corrected can be overridden ## by the variable @var{t}. ## ## If the file is not an integer multiple of the message size (127 or 255) ## in length, then the file is padded with the EOT (ascii character 4) ## characters before coding. Whether these characters are written to the ## output is defined by the @var{pad} variable. Valid values for @var{pad} ## are "pad" (the default) and "nopad", which write or not the padding ## respectively. ## ## @end deftypefn ## @seealso{rsdecof} function rsencof(in, out, varargin) if ((nargin < 2) || (nargin > 4)) usage("rsencof (in, out [, t [, pad]])"); endif if (!ischar(in) || !ischar(out)) error ("rsencof: input and output filenames must be strings"); endif t = 0; pad = 1; for i=1:length(varargin) arg = varargin{i}; if (ischar(arg)) if (strcmp(arg,"pad")) pad = 1; elseif (strcmp(arg,"nopad")) pad = 0; else error ("rsencof: unrecognized string argument"); endif else if (!isscalar(t) || (t != floor(d)) || (t < 1)) error ("rsencof: t must be a postive, non-zero integer"); endif endif end try fid = fopen(in, "r"); catch error ("rsencof: can not open input file"); end [msg, count] = fread(fid, Inf, "char"); fclose(fid); is8bit = (max(msg) > 127); if (is8bit) m = 8; n = 255; if (t == 0) t = 10; endif else m = 7; n = 127; if (t == 0) t = 5; endif endif k = n - 2 * t; ncodewords = ceil(count / k); npad = k * ncodewords - count; msg = reshape([msg ; 4 * ones(npad,1)],k,ncodewords)'; code = rsenc(gf(msg,m), n, k,"beginning")'; code = code(:); try fid = fopen(out, "w"); catch error ("rsencof: can not open output file"); end if (pad) fwrite(fid, code, "char"); else fwrite(fid, code(1:(ncodewords*n-npad)), "char"); endif fclose(fid); endfunction