54 lines
1.3 KiB
C++
54 lines
1.3 KiB
C++
// Simple low-pass and high-pass filter to better match sound output of a SNES
|
|
|
|
// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
|
|
#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 );
|
|
|
|
// Enables/disables filtering (when disabled, gain is still applied)
|
|
void enable( bool b );
|
|
|
|
// 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;
|
|
bool enabled;
|
|
struct chan_t { int p1, pp1, sum; };
|
|
chan_t ch [2];
|
|
};
|
|
|
|
inline void SPC_Filter::enable( bool b ) { enabled = b; }
|
|
|
|
inline void SPC_Filter::set_gain( int g ) { gain = g; }
|
|
|
|
inline void SPC_Filter::set_bass( int b ) { bass = b; }
|
|
|
|
#endif
|