Added DaisySP

daisysp/Filters/svf.h

@@ -0,0 +1,87 @@
+/*
+Copyright (c) 2020 Electrosmith, Corp
+
+Use of this source code is governed by an MIT-style
+license that can be found in the LICENSE file or at
+https://opensource.org/licenses/MIT.
+*/
+
+#pragma once
+#ifndef DSY_SVF_H
+#define DSY_SVF_H
+
+namespace daisysp
+{
+/**      Double Sampled, Stable State Variable Filter
+
+Credit to Andrew Simper from musicdsp.org
+
+This is his "State Variable Filter (Double Sampled, Stable)"
+
+Additional thanks to Laurent de Soras for stability limit, and 
+Stefan Diedrichsen for the correct notch output
+
+Ported by: Stephen Hensley
+*/
+class Svf
+{
+  public:
+    Svf() {}
+    ~Svf() {}
+    /** Initializes the filter
+        float sample_rate - sample rate of the audio engine being run, and the frequency that the Process function will be called.
+    */
+    void Init(float sample_rate);
+
+
+    /** 
+        Process the input signal, updating all of the outputs.
+    */
+    void Process(float in);
+
+
+    /** sets the frequency of the cutoff frequency. 
+        f must be between 0.0 and sample_rate / 3
+    */
+    void SetFreq(float f);
+
+    /** sets the resonance of the filter.
+        Must be between 0.0 and 1.0 to ensure stability.
+    */
+    void SetRes(float r);
+
+    /** sets the drive of the filter 
+        affects the response of the resonance of the filter
+    */
+    void SetDrive(float d);
+    /** lowpass output
+        \return low pass output of the filter
+    */
+    inline float Low() { return out_low_; }
+    /** highpass output
+        \return high pass output of the filter
+    */
+    inline float High() { return out_high_; }
+    /** bandpass output
+        \return band pass output of the filter
+    */
+    inline float Band() { return out_band_; }
+    /** notchpass output
+        \return notch pass output of the filter
+    */
+    inline float Notch() { return out_notch_; }
+    /** peak output
+        \return peak output of the filter
+    */
+    inline float Peak() { return out_peak_; }
+
+  private:
+    float sr_, fc_, res_, drive_, freq_, damp_;
+    float notch_, low_, high_, band_, peak_;
+    float input_;
+    float out_low_, out_high_, out_band_, out_peak_, out_notch_;
+    float pre_drive_, fc_max_;
+};
+} // namespace daisysp
+
+#endif