IIR.h

00001 #ifndef IIR_H
00002 #define IIR_H
00003 
00004 #include <vector>
00005 using std::vector;
00006 /*-----------------------------*/
00007 //   Order of the numerator: m
00008 //   Orser of the denominator: n
00009 //--------------------------------//
00010 //
00011 //    y     gain*( sum(i from 0 to m) b[i]*x[k-i] )
00012 //   --- = --------------------------------------------
00013 //    u     1 + sum( i from 1 to n) a[i]*y[k-i]
00014 //
00015 //   y[k] = gain*( sum(i from 0 to m) b[i]*x[k-i] ) - sum( i from 1 to n) a[i]*y[k-i]
00016 //
00017 //   Compatible with the coefficient generated by Matlab fdatool
00018 //
00019 //   by C.F. Huang from LDSC
00020 /*-----------------------------*/
00021 
00022 class Circular_buffer{
00023 private:
00024     size_t n;
00025     vector<float> A;
00026     // vector<float>::iterator it;
00027     int ind; // The index of the newest element
00028 
00029 public:
00030     Circular_buffer();
00031     Circular_buffer(int n_in);
00032     //
00033     void Init(int n_in);
00034     //
00035     float Get(int i); // Get the value of the (t-i)th element, where t stands for the current sample
00036     void Insert(float x_new); // Pop the oldest element and push a new element
00037     void reset(float val); // Reset all elements to val
00038 };
00039 
00040 class IIR{
00041 private:
00042 
00043     int m; // the order of numerator
00044     int n; // the order of denominator
00045     Circular_buffer x,y;
00046     vector<float> b; // parameters of numerator, highest order --> lowest order (newest -> oldest)
00047     vector<float> a; // parameters of denominator, highest order --> lowest order (newest -> oldest)
00048     float gain;
00049 
00050 public:
00051     //
00052     IIR(int m, int n);
00053     //
00054     void Assign_parameters(float b_in[], float a_in[], float gain_in);
00055     //
00056     float Iterate_once(float x_in);
00057     void Reset(float val);
00058 };
00059 
00060 #endif