Code

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

David Valencia December 5, 2010 Coded in Matlab

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 José 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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