Initial community commit

Src/Winamp/benskiQ/Biquad.h

@@ -0,0 +1,29 @@
+#pragma once
+
+class Biquad
+{
+public:
+	Biquad();
+	void copy_filter(const Biquad &other);
+	void SetSampleRate(double fs);
+	void set_freq(double f0);
+	void set_s_eq(const double b[3], const double a[3]);
+	void transform_s_to_z();
+
+	void process_block(float *dest_ptr, const float *src_ptr, long nbr_spl);
+	void clear_buffers();
+
+private:
+	double _s_eq_b[3]; // Coefs for numerator (zeros)
+	double _s_eq_a[3]; // Coefs for denominator (poles)
+	double _z_eq_b[3]; // Direct coefficients, order z^(-n)
+	double _z_eq_a[3]; // Recursive coefficients, order z^(-n)
+	double sampleRate; // Hz, > 0
+	double _f0; // Hz, > 0, _f0 % (_sample_freq/2) != 0
+	double xn[2]; // Input memory, order z^(-n)
+	double yn[2]; // Output memory, order z^(-n)
+	int _mem_pos; // 0 or 1
+
+	inline double process_sample(double x);
+};
+