123 lines
2.8 KiB
C
123 lines
2.8 KiB
C
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/* libiir/src/libiir++/100_Coeff.h
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*
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* Copyright: ©2014, Laurence Withers.
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* Author: Laurence Withers <l@lwithers.me.uk>
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* License: GPLv3
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*/
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/*! \defgroup libiirpp_coeff Coefficient handling
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\ingroup libiirpp
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A set of coefficients for a single stage %IIR filter is represented by an
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instance of the \ref Coeff class. This class is often instantiated through
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one of the common filter generator functions (see \ref libiirpp_common_filters).
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*/
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/*! \brief %IIR filter coefficient set
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\ingroup libiirpp_coeff
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An instance of this class represents the set of coefficients used to implement
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a single-phase %IIR filter. See \ref iir_structure for more information.
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*/
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class Coeff {
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public:
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/*! \brief Constructor with raw coefficients.
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\param nc Number of \a c coefficients, ≥ 1.
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\param c Array of \a c coefficients.
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\param nd Number of \a d coefficients, ≥ 1.
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\param d Array of \a d coefficients.
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*/
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Coeff(int nc, const double* c, int nd, const double* d);
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/*! \brief Constructor from C library object.
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\param cc Pointer to existing coefficient object.
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*/
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Coeff(const struct iir_coeff_t* cc);
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/*! \brief Copy constructor.
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\param other Object to copy.
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Performs a full deep copy of the set of coefficients from \a other.
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*/
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Coeff(const Coeff& other);
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/*! \brief Destructor. */
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virtual ~Coeff();
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/*! \brief Count number of \a c coefficients.
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\returns Number of \a c coefficients, ≥ 1.
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*/
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int nc() const;
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/*! \brief Retrieve \a c coefficient by index.
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\param idx Index of coefficient (0 ≤ \a idx < \ref nc()).
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\returns Value of \a c coefficient at index \a idx.
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*/
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double c(int idx) const;
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/*! \brief Count number of \a d coefficients.
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\returns Number of \a d coefficients, ≥ 1.
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*/
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int nd() const;
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/*! \brief Retrieve \a d coefficient by index.
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\param idx Index of coefficient (0 ≤ \a idx < \ref nd()).
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\returns Value of \a d coefficient at index \a idx.
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*/
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double d(int idx) const;
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/*! \brief Evaluate response of filter at given frequency.
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\param freq Frequency (0 ≤ \a freq ≤ 1).
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\returns Complex response of filter at given frequency.
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Returns the steady-state response of the filter to a pure input signal of
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the given frequency. \a freq is expressed as a fraction of the intended
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sampling rate (with 0.5 being the Nyquist frequency).
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*/
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std::complex<double> response(double freq) const;
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private:
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// allow the Filter class to access cc_ directly
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friend class Filter;
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// our internal representation is the C object
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struct iir_coeff_t* cc_;
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// disallow assignment; object is immutable
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Coeff& operator=(const Coeff& other);
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};
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/* options for text editors
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vim: expandtab:ts=4:sw=4:syntax=cpp.doxygen
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*/
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