Added DaisySP

daisysp/Filters/soap.cpp

@@ -0,0 +1,65 @@
+#include "soap.h"
+#include <cmath>
+
+#define PI 3.141592653589793
+
+using namespace daisysp;
+
+void Soap::Init(float sample_rate)
+{
+    soap_center_freq_ = 400.0;
+    soap_bandwidth_   = 50.0;
+    in_0_             = 0.0; // input            x0
+    din_1_            = 0.0; // delayed input    x1
+    din_2_            = 0.0; // delayed input    x2
+    dout_1_           = 0.0; // delayed output   y1
+    dout_2_           = 0.0; // delayed output   y2
+    all_output_       = 0.0; // all pass output  y0
+    out_bandpass_     = 0.0; // bandpass output
+    out_bandreject_   = 0.0; // bandreject output
+    sr_               = sample_rate;
+    return;
+}
+
+void Soap::Process(float in)
+{
+    // recalculate the coefficients, later move this to a lookup table
+    float d = -std::cos(2.0 * PI * (soap_center_freq_ / sr_));
+
+    // tangent bandwidth
+    float tf = std::tan(PI * (soap_bandwidth_ / sr_));
+
+    // coefficient
+    float c = (tf - 1.0) / (tf + 1.0);
+
+    in_0_ = in;
+
+    all_output_ = -c * in_0_ + (d - d * c) * din_1_ + din_2_
+                  - (d - d * c) * dout_1_ + c * dout_2_;
+
+    // move samples in delay for next sample
+    din_2_  = din_1_;
+    din_1_  = in_0_;
+    dout_2_ = dout_1_;
+    dout_1_ = all_output_;
+
+    // make factor -1.0 to create a bandpass
+    out_bandpass_ = (in_0_ + all_output_ * -1.0) * 0.5;
+
+    // make factor +1.0 to create a bandreject
+    out_bandreject_ = (in_0_ + all_output_ * 0.99) * 0.5;
+
+    return;
+}
+
+void Soap::SetCenterFreq(float f)
+{
+    soap_center_freq_ = f;
+    return;
+}
+
+void Soap::SetFilterBandwidth(float b)
+{
+    soap_bandwidth_ = b;
+    return;
+}