prd.m

ADSL经典仿真程序

%PRD pseudo random binary number generator.
%
% X = PRD(M) returns M binary numbers in X. M has to be greater than
% 0 and smaller than 512.

% Copyright (c) 1999-2003 The University of Texas
% All Rights Reserved.
%  
% 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.
%  
% The GNU Public License is available in the file LICENSE, or you
% can write to the Free Software Foundation, Inc., 59 Temple Place -
% Suite 330, Boston, MA 02111-1307, USA, or you can find it on the
% World Wide Web at http://www.fsf.org.
%  
% Programmers:	Guner Arslan
% Version:        %W% %G%
% 
% The authors are with the Department of Electrical and Computer
% Engineering, The University of Texas at Austin, Austin, TX.
% They can be reached at [e-mail].
% Guner Arslan is also with the Embedded Signal Processing
% Laboratory in the Dept. of ECE, http://signal.ece.utexas.edu.

function x = prd(M)

if M < 0 | M > 512
   M = 512;
end

for n = 1:512

   if n>=1 & n<=9
      y(n) = 1;
   else
      y(n) = xor(y(n-4),y(n-9));
   end
end

x = y(1:M);