synth_filter_decim2.m

来自「This lab exercise will introduce you to 」· M 代码 · 共 36 行

%       AccelDSP 8.1.1 build 690 Production, compiled Apr 26 2006 
% 
%    THIS IS UNPUBLISHED, LICENSED SOFTWARE THAT IS THE CONFIDENTIAL 
%        AND PROPRIETARY PROPERTY OF XILINX OR ITS LICENSORS 
% 
%     Copyright(c) Xilinx, Inc., 2000-2006, All Rights Reserved. 
%     Reproduction or reuse, in any form, without the explicit written 
%     consent of Xilinx, Inc., is strictly prohibited. 

function [FilterOut,valid] = synth_filter_decim2(FilterIn)

coeff = load('b.txt');

persistent tap_delay count sum1 sum2
if isempty(tap_delay)
  tap_delay = zeros(1,length(coeff));
  count = 0;
  sum1 = 0;
  sum2 = 0;
end

% Perform sum of products for the polyphase decimation by 2 filter
if count == 0
   sum1 = tap_delay(2:2:end) * coeff(end:-2:2)';
   count = 1;
   valid = 0;
else
   sum2 = tap_delay(2:2:end) * coeff(end-1:-2:1)';
   count = 0;
   valid = 1;
end

FilterOut = sum1+sum2;

% Shift tap delay line
tap_delay = [tap_delay(2:length(coeff)) FilterIn];