new dsp

core/src/dsp/window.h

@@ -0,0 +1,75 @@
+#pragma once
+#include <dsp/block.h>
+
+namespace dsp {
+    namespace filter_window {
+        class generic_window {
+        public:
+            virtual int getTapCount() { return -1; }
+            virtual void createTaps(float* taps, int tapCount) {}
+        };
+
+        class BlackmanWindow : public filter_window::generic_window {
+        public:
+            BlackmanWindow() {}
+            BlackmanWindow(float cutoff, float transWidth, float sampleRate) { init(cutoff, transWidth, sampleRate); }
+
+            void init(float cutoff, float transWidth, float sampleRate) {
+                _cutoff = cutoff;
+                _transWidth = transWidth;
+                _sampleRate = sampleRate;
+            }
+
+            void setSampleRate(float sampleRate) {
+                _sampleRate = sampleRate;
+            }
+
+            void setCutoff(float cutoff) {
+                _cutoff = cutoff;
+            }
+
+            void setTransWidth(float transWidth) {
+                _transWidth = transWidth;
+            }
+
+            int getTapCount() {
+                float fc = _cutoff / _sampleRate;
+                if (fc > 1.0f) {
+                    fc = 1.0f;
+                }
+
+                int _M = 4.0f / (_transWidth / _sampleRate);
+                if (_M < 4) {
+                    _M = 4;
+                }
+
+                if (_M % 2 == 0) { _M++; }
+
+                return _M;
+            }
+
+            void createTaps(float* taps, int tapCount) {
+                float fc = _cutoff / _sampleRate;
+                if (fc > 1.0f) {
+                    fc = 1.0f;
+                }
+                float tc = tapCount;
+                float sum = 0.0f;
+                float val;
+                for (int i = 0; i < tapCount; i++) {
+                    val = (sin(2.0f * FL_M_PI * fc * ((float)i - (tc / 2))) / ((float)i - (tc / 2))) * 
+                        (0.42f - (0.5f * cos(2.0f * FL_M_PI / tc)) + (0.8f * cos(4.0f * FL_M_PI / tc)));
+                    taps[tapCount - i - 1] = val; // tapCount - i - 1
+                    sum += val;
+                }
+                for (int i = 0; i < tapCount; i++) {
+                    taps[i] /= sum;
+                }
+            }
+
+        private:
+            float _cutoff, _transWidth, _sampleRate;
+
+        };
+    }
+}