// Simple low-pass and high-pass filter to better match sound output of a SNES

 

 // snes_spc 0.9.0

 #ifndef SPC_FILTER_H

 #define SPC_FILTER_H

 

 #include "blargg_common.h"

 

 struct SPC_Filter {

 public:

 	

 	// Filters count samples of stereo sound in place. Count must be a multiple of 2.

 	typedef short sample_t;

 	void run( sample_t* io, int count );

 	

 // Optional features

 

 	// Clears filter to silence

 	void clear();

 

 	// Sets gain (volume), where gain_unit is normal. Gains greater than gain_unit

 	// are fine, since output is clamped to 16-bit sample range.

 	enum { gain_unit = 0x100 };

 	void set_gain( int gain );

 

 	// Sets amount of bass (logarithmic scale)

 	enum { bass_none =  0 };

 	enum { bass_norm =  8 }; // normal amount

 	enum { bass_max  = 31 };

 	void set_bass( int bass );

 	

 public:

 	SPC_Filter();

 	BLARGG_DISABLE_NOTHROW

 private:

 	enum { gain_bits = 8 };

 	int gain;

 	int bass;

 	struct chan_t { int p1, pp1, sum; };

 	chan_t ch [2];

 };

 

 inline void SPC_Filter::set_gain( int g ) { gain = g; }

 

 inline void SPC_Filter::set_bass( int b ) { bass = b; }

 

 #endif