chore(fmod): add files from Chensne/DragonNest

lib/freeverb/comb.h

@@ -0,0 +1,55 @@
+// Comb filter class declaration
+//
+// Written by Jezar at Dreampoint, June 2000
+// http://www.dreampoint.co.uk
+// This code is public domain
+
+#ifndef _comb_
+#define _comb_
+
+#include "denormals.h"
+
+class comb
+{
+public:
+					comb();
+			void	setbuffer(float *buf, int size);
+	inline  float	process(float inp);
+			void	mute();
+			void	setdamp(float val);
+			float	getdamp();
+			void	setfeedback(float val);
+			float	getfeedback();
+private:
+	float	feedback;
+	float	filterstore;
+	float	damp1;
+	float	damp2;
+	float	*buffer;
+	int		bufsize;
+	int		bufidx;
+};
+
+
+// Big to inline - but crucial for speed
+
+inline float comb::process(float input)
+{
+	float output;
+
+	output = buffer[bufidx];
+	undenormalise(output);
+
+	filterstore = (output*damp2) + (filterstore*damp1);
+	undenormalise(filterstore);
+
+	buffer[bufidx] = input + (filterstore*feedback);
+
+	if(++bufidx>=bufsize) bufidx = 0;
+
+	return output;
+}
+
+#endif //_comb_
+
+//ends