--- /dev/null
+## Copyright (C) 2006 Muthiah Annamalai <muthiah.annamalai@uta.edu>
+##
+## 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/>.
+
+## Implement book keeping for a Pseudo-Random Binary Sequence ( PRBS )
+## also called as a Linear Feedback Shift Register.
+##
+## Given a polynomial create a PRBS structure for that polynomial.
+## Now all we need is to just create this polynomial and make it work.
+## polynomial must be a vector containing the powers of x and an optional
+## value 1. eg: x^3 + x^2 + x + 1 must be written as [3 2 1 0]
+## all the coefficients are either 1 or 0. It generates only a Binary \
+## sequence, and the generator polynomial need to be only a binary
+## polynomial in GF(2).
+##
+## connections, contains a struct of vectors where each vector is the
+## connection list mapping its vec(2:end) elements to the vec(1) output.
+##
+## Example: If you had a PRBS shift register like the diagram
+## below with 4 registers we use representation by polynomial
+## of [ 1 2 3 4], and feedback connections between [ 1 3 4 ].
+## The output PRBS sequence is taken from the position 4.
+##
+## +---+ +----+ +---+ +---+
+## | D |----| D |---| D |---| D |
+## +---+ +----+ +---+ +---+
+## | | |
+## \ / /
+## [+]---------------+------+
+## 1 + 0.D + 1.D^2 + 1.D^3
+##
+## The code to implement this PRBS with a start state of [1 0 1 1]
+## will be:
+##
+## prbs=prbs_generator([1 3 4],{[1 3 4]},[1 0 1 1]);
+## x = prbs_sequence(prbs) #gives 15
+##
+## prbs_iterator( prbs, 15 ) #15 binary digits seen
+## [ 1 1 0 1 0 1 1 1 1 0 0 0 1 0 0 ]
+##
+## See Also: This function is to be used along with functions
+## prbs_iterator, and prbs_sequence.
+
+function prbs=prbs_generator(polynomial,connections,initstate)
+ prbs.reglen=max(polynomial);
+ prbs.polynomial=polynomial;
+ prbs.sregs=initstate;
+ prbs.connections=connections;
+ prbs.conlen=length(connections);
+end