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- /*******************************************************************************
-
- "A Collection of Useful C++ Classes for Digital Signal Processing"
- By Vinnie Falco
-
- Official project location:
- https://github.com/vinniefalco/DSPFilters
-
- See Documentation.cpp for contact information, notes, and bibliography.
-
- --------------------------------------------------------------------------------
-
- License: MIT License (http://www.opensource.org/licenses/mit-license.php)
- Copyright (c) 2009 by Vinnie Falco
-
- Permission is hereby granted, free of charge, to any person obtaining a copy
- of this software and associated documentation files (the "Software"), to deal
- in the Software without restriction, including without limitation the rights
- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- copies of the Software, and to permit persons to whom the Software is
- furnished to do so, subject to the following conditions:
-
- The above copyright notice and this permission notice shall be included in
- all copies or substantial portions of the Software.
-
- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- THE SOFTWARE.
-
- *******************************************************************************/
- #pragma once
-
- #include "Common.h"
- #include "Cascade.h"
- #include "Design.h"
- #include "Filter.h"
- #include "PoleFilter.h"
- #include "RootFinder.h"
-
- namespace Dsp
- {
-
- /*
- * Filters with Legendre / "Optimum-L" response characteristics
- *
- */
-
- namespace Legendre
- {
-
- // Numerical computation of Legendre "Optimum-L" polynomials
-
- class PolynomialFinderBase
- {
- public:
- void solve(int n);
-
- double* coef() { return m_w; }
-
- private:
- void legendre(double* p, int n);
-
- protected:
- int m_maxN = 0;
- double* m_w = nullptr;
- double* m_a = nullptr;
- double* m_p = nullptr;
- double* m_s = nullptr;
- double* m_v = nullptr;
- double* m_aa = nullptr;
- double* m_bb = nullptr;
- };
-
- template <int maxN>
- class PolynomialFinder : public PolynomialFinderBase
- {
- public:
- PolynomialFinder()
- {
- m_maxN = maxN;
- m_w = m_ws;
- m_a = m_as;
- m_p = m_ps;
- m_s = m_ss;
- m_v = m_vs;
- m_aa = m_aas;
- m_bb = m_bbs;
- }
-
- void solve(int n)
- {
- assert(n <= maxN);
- PolynomialFinderBase::solve(n);
- }
-
- private:
- double m_ws [2 * maxN + 1];
- double m_as [ maxN + 1];
- double m_ps [2 * maxN + 1];
- double m_ss [2 * maxN + 1];
- double m_vs [2 * maxN + 4];
- double m_aas [ maxN + 1];
- double m_bbs [ maxN + 1];
- };
-
- //------------------------------------------------------------------------------
-
- // A Workspace is necessary to construct the polynomial and find its roots
-
- struct WorkspaceBase
- {
- WorkspaceBase(PolynomialFinderBase* polyBase, RootFinderBase* rootsBase) : poly(*polyBase), roots(*rootsBase) { }
-
- PolynomialFinderBase& poly;
- RootFinderBase& roots;
-
- private:
- WorkspaceBase(WorkspaceBase&);
- WorkspaceBase& operator=(WorkspaceBase&);
- };
-
- template <int MaxOrder>
- struct Workspace : WorkspaceBase
- {
- Workspace() : WorkspaceBase(&m_poly, &m_roots) { }
-
- private:
- PolynomialFinder<MaxOrder> m_poly;
- RootFinder<MaxOrder * 2> m_roots;
- };
-
- //------------------------------------------------------------------------------
-
- // Half-band analog prototypes (s-plane)
-
- class AnalogLowPass : public LayoutBase
- {
- public:
- AnalogLowPass();
-
- void design(int numPoles, WorkspaceBase* w);
-
- private:
- int m_numPoles = 0;
- };
-
- //------------------------------------------------------------------------------
-
- // Factored implementations to reduce template instantiations
-
- struct LowPassBase : PoleFilterBase<AnalogLowPass>
- {
- void setup(int order, double sampleRate, double cutoffFrequency, WorkspaceBase* w);
- };
-
- struct HighPassBase : PoleFilterBase<AnalogLowPass>
- {
- void setup(int order, double sampleRate, double cutoffFrequency, WorkspaceBase* w);
- };
-
- struct BandPassBase : PoleFilterBase<AnalogLowPass>
- {
- void setup(int order, double sampleRate, double centerFrequency, double widthFrequency, WorkspaceBase* w);
- };
-
- struct BandStopBase : PoleFilterBase<AnalogLowPass>
- {
- void setup(int order, double sampleRate, double centerFrequency, double widthFrequency, WorkspaceBase* w);
- };
-
- //------------------------------------------------------------------------------
-
- //
- // Raw filters
- //
-
- template <int MaxOrder>
- struct LowPass : PoleFilter<LowPassBase, MaxOrder>
- {
- void setup(int order, double sampleRate, double cutoffFrequency)
- {
- Workspace<MaxOrder> w;
- LowPassBase::setup(order, sampleRate, cutoffFrequency, &w);
- }
- };
-
- template <int MaxOrder>
- struct HighPass : PoleFilter<HighPassBase, MaxOrder>
- {
- void setup(int order, double sampleRate, double cutoffFrequency)
- {
- Workspace<MaxOrder> w;
- HighPassBase::setup(order, sampleRate, cutoffFrequency, &w);
- }
- };
-
- template <int MaxOrder>
- struct BandPass : PoleFilter<BandPassBase, MaxOrder, MaxOrder * 2>
- {
- void setup(int order, double sampleRate, double centerFrequency, double widthFrequency)
- {
- Workspace<MaxOrder> w;
- BandPassBase::setup(order, sampleRate, centerFrequency, widthFrequency, &w);
- }
- };
-
- template <int MaxOrder>
- struct BandStop : PoleFilter<BandStopBase, MaxOrder, MaxOrder * 2>
- {
- void setup(int order, double sampleRate, double centerFrequency, double widthFrequency)
- {
- Workspace<MaxOrder> w;
- BandStopBase::setup(order, sampleRate, centerFrequency, widthFrequency, &w);
- }
- };
-
- //------------------------------------------------------------------------------
-
- //
- // Gui-friendly Design layer
- //
-
- namespace Design
- {
- struct TypeIBase : DesignBase
- {
- enum
- {
- NumParams = 3
- };
-
- static int getNumParams() { return 3; }
- static ParamInfo getParamInfo_2() { return ParamInfo::defaultCutoffFrequencyParam(); }
- };
-
- template <class FilterClass>
- struct TypeI : TypeIBase, FilterClass
- {
- void setParams(const Params& params) { FilterClass::setup(int(params[1]), params[0], params[2]); }
- };
-
- struct TypeIIBase : DesignBase
- {
- enum
- {
- NumParams = 4
- };
-
- static int getNumParams() { return 4; }
- static ParamInfo getParamInfo_2() { return ParamInfo::defaultCenterFrequencyParam(); }
- static ParamInfo getParamInfo_3() { return ParamInfo::defaultBandwidthHzParam(); }
- };
-
- template <class FilterClass>
- struct TypeII : TypeIIBase, FilterClass
- {
- void setParams(const Params& params) { FilterClass::setup(int(params[1]), params[0], params[2], params[3]); }
- };
-
- // Factored kind and name
-
- struct LowPassDescription
- {
- static Kind getKind() { return kindLowPass; }
- static const char* getName() { return "Legendre Low Pass"; }
- };
-
- struct HighPassDescription
- {
- static Kind getKind() { return kindHighPass; }
- static const char* getName() { return "Legendre High Pass"; }
- };
-
- struct BandPassDescription
- {
- static Kind getKind() { return kindHighPass; }
- static const char* getName() { return "Legendre Band Pass"; }
- };
-
- struct BandStopDescription
- {
- static Kind getKind() { return kindHighPass; }
- static const char* getName() { return "Legendre Band Stop"; }
- };
-
- // This glues on the Order parameter
- template <int MaxOrder, template <class> class TypeClass, template <int> class FilterClass>
- struct OrderBase : TypeClass<FilterClass<MaxOrder>>
- {
- ParamInfo getParamInfo_1() const
- {
- return ParamInfo(idOrder, "Order", "Order", 1, MaxOrder, 2, &ParamInfo::Int_toControlValue, &ParamInfo::Int_toNativeValue,
- &ParamInfo::Int_toString);
- }
- };
-
- //------------------------------------------------------------------------------
-
- //
- // Design filters
- //
-
- template <int MaxOrder>
- struct LowPass : OrderBase<MaxOrder, TypeI, Legendre::LowPass>, LowPassDescription {};
-
- template <int MaxOrder>
- struct HighPass : OrderBase<MaxOrder, TypeI, Legendre::HighPass>, HighPassDescription {};
-
- template <int MaxOrder>
- struct BandPass : OrderBase<MaxOrder, TypeII, Legendre::BandPass>, BandPassDescription {};
-
- template <int MaxOrder>
- struct BandStop : OrderBase<MaxOrder, TypeII, Legendre::BandStop>, BandStopDescription {};
- } // namespace Design
- } // namespace Legendre
- } // namespace Dsp
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