## Copyright (C) 2018 Jens Ahrensfeld
## 
## 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{retval} =} gardner_eval (@var{input1}, @var{input2})
##
## @seealso{}
## @end deftypefn

## Author: Jens Ahrensfeld <ahrensfeld@w2ess001vm>
## Created: 2018-12-13

function gardner_eval (x, nBitsPerSample, phase)
if mod(nBitsPerSample, 2)
	error ("nBitsPerSample must be divisable by 2!");
end

Z = zeros(1,3);

countReload = nBitsPerSample/2;
count = countReload-1;
N = length(x);
vc = 0;
k = 1;
for n=1:N,

	if count == phase
		Z = [x(n) Z(1:2)];
		vc = Z(2) * (Z(3) - Z(1));
		_y(k) = x(n);
		k = k + 1;
	end

	if count == 0
		count = countReload-1;
	else
		count = count - 1;
	end
	
	_vc(n) = vc;
end


subplot(2,1 ,1)
plot(1:N, _vc); grid;
subplot(2,1 ,2)
plot(1:k-1, _y, '-o'); grid;
endfunction