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00022 #ifndef _GR_SINGLE_POLE_IIR_H_
00023 #define _GR_SINGLE_POLE_IIR_H_
00024
00025 #include <stdexcept>
00026
00030 template<class o_type, class i_type, class tap_type>
00031 class gr_single_pole_iir {
00032 public:
00038 gr_single_pole_iir (tap_type alpha = 1.0)
00039 {
00040 d_prev_output = 0;
00041 set_taps (alpha);
00042 }
00043
00048 o_type filter (const i_type input);
00049
00054 void filterN (o_type output[], const i_type input[], unsigned long n);
00055
00059 void set_taps (tap_type alpha)
00060 {
00061 if (alpha < 0 || alpha > 1)
00062 throw std::out_of_range ("Alpha must be in [0, 1]\n");
00063
00064 d_alpha = alpha;
00065 d_one_minus_alpha = 1.0 - alpha;
00066 }
00067
00069 void reset ()
00070 {
00071 d_prev_output = 0;
00072 }
00073
00074 protected:
00075 tap_type d_alpha;
00076 tap_type d_one_minus_alpha;
00077 tap_type d_prev_output;
00078 };
00079
00080
00081
00082
00083
00084 template<class o_type, class i_type, class tap_type>
00085 o_type
00086 gr_single_pole_iir<o_type, i_type, tap_type>::filter (const i_type input)
00087 {
00088 tap_type output;
00089
00090 output = d_alpha * input + d_one_minus_alpha * d_prev_output;
00091 d_prev_output = output;
00092
00093 return (o_type) output;
00094 }
00095
00096
00097 template<class o_type, class i_type, class tap_type>
00098 void
00099 gr_single_pole_iir<o_type, i_type, tap_type>::filterN (o_type output[],
00100 const i_type input[],
00101 unsigned long n)
00102 {
00103 for (unsigned i = 0; i < n; i++)
00104 output[i] = filter (input[i]);
00105 }
00106
00107
00108 #endif