1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/snes_spc/SPC_Filter.h	Fri Oct 21 05:53:11 2011 -0700
     1.3 @@ -0,0 +1,47 @@
     1.4 +// Simple low-pass and high-pass filter to better match sound output of a SNES
     1.5 +
     1.6 +// snes_spc 0.9.0
     1.7 +#ifndef SPC_FILTER_H
     1.8 +#define SPC_FILTER_H
     1.9 +
    1.10 +#include "blargg_common.h"
    1.11 +
    1.12 +struct SPC_Filter {
    1.13 +public:
    1.14 +	
    1.15 +	// Filters count samples of stereo sound in place. Count must be a multiple of 2.
    1.16 +	typedef short sample_t;
    1.17 +	void run( sample_t* io, int count );
    1.18 +	
    1.19 +// Optional features
    1.20 +
    1.21 +	// Clears filter to silence
    1.22 +	void clear();
    1.23 +
    1.24 +	// Sets gain (volume), where gain_unit is normal. Gains greater than gain_unit
    1.25 +	// are fine, since output is clamped to 16-bit sample range.
    1.26 +	enum { gain_unit = 0x100 };
    1.27 +	void set_gain( int gain );
    1.28 +
    1.29 +	// Sets amount of bass (logarithmic scale)
    1.30 +	enum { bass_none =  0 };
    1.31 +	enum { bass_norm =  8 }; // normal amount
    1.32 +	enum { bass_max  = 31 };
    1.33 +	void set_bass( int bass );
    1.34 +	
    1.35 +public:
    1.36 +	SPC_Filter();
    1.37 +	BLARGG_DISABLE_NOTHROW
    1.38 +private:
    1.39 +	enum { gain_bits = 8 };
    1.40 +	int gain;
    1.41 +	int bass;
    1.42 +	struct chan_t { int p1, pp1, sum; };
    1.43 +	chan_t ch [2];
    1.44 +};
    1.45 +
    1.46 +inline void SPC_Filter::set_gain( int g ) { gain = g; }
    1.47 +
    1.48 +inline void SPC_Filter::set_bass( int b ) { bass = b; }
    1.49 +
    1.50 +#endif