## DWT filter generator - formfilters.m (for chain processing)

Used for the chain-processing version of the DWT program.

For details go to the blog post:

http://www.dsprelated.com/showarticle/126.php

```
% Created by JosÃ© David Valencia Pesqueira
% UPIITA-IPN 2010
% For the DWT chain-processing example
% as posted in DSPrelated.com
% http://www.dsprelated.com/showcode/44.php
%
function [hx] = formfilters(n_stages,branch,h0,h1)
p = branch;
% Seed vector
hx = 0;
hx(1) = 1;
switch n_stages
case 1
if mod(branch,2) ~= 0
hx = h0;
else
hx = h1;
end
case 2
switch branch
case 1
hx = conv(h0,upsample2(h0,2));
case 2
hx = conv(h0,upsample2(h1,2));
case 3
hx = conv(h1,upsample2(h0,2));
case 4
hx = conv(h1,upsample2(h1,2));
otherwise
beep;
fprintf('\nFor a 2-stage bank there cannot be a fifth branch');
end
otherwise
for i=0:n_stages-2
q = floor(p /(2^(n_stages-1-i)));
if (q == 1)
hx = conv(hx,upsample2(h1,2^i));
else
hx = conv(hx,upsample2(h0,2^i));
end
% p = mod(p,2^(n_stages-1-i)); %For DWPT
p = mod(2^(n_stages-1-i),p); %For DWT
end
t = mod(branch,2);
if(t == 1)
hx = conv(hx,upsample2(h0,2^(n_stages-1)));
else
hx = conv(hx,upsample2(h1,2^(n_stages-1)));
end
end
```

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