gzdoom/game-music-emu/gme/Nes_Vrc6_Apu.h

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// Konami VRC6 sound chip emulator
// Nes_Snd_Emu 0.1.8
#ifndef NES_VRC6_APU_H
#define NES_VRC6_APU_H
#include "blargg_common.h"
#include "Blip_Buffer.h"
struct vrc6_apu_state_t;
class Nes_Vrc6_Apu {
public:
// See Nes_Apu.h for reference
void reset();
void volume( double );
void treble_eq( blip_eq_t const& );
void output( Blip_Buffer* );
enum { osc_count = 3 };
void osc_output( int index, Blip_Buffer* );
void end_frame( blip_time_t );
void save_state( vrc6_apu_state_t* ) const;
void load_state( vrc6_apu_state_t const& );
// Oscillator 0 write-only registers are at $9000-$9002
// Oscillator 1 write-only registers are at $A000-$A002
// Oscillator 2 write-only registers are at $B000-$B002
enum { reg_count = 3 };
enum { base_addr = 0x9000 };
enum { addr_step = 0x1000 };
void write_osc( blip_time_t, int osc, int reg, int data );
public:
Nes_Vrc6_Apu();
BLARGG_DISABLE_NOTHROW
private:
// noncopyable
Nes_Vrc6_Apu( const Nes_Vrc6_Apu& );
Nes_Vrc6_Apu& operator = ( const Nes_Vrc6_Apu& );
struct Vrc6_Osc
{
BOOST::uint8_t regs [3];
Blip_Buffer* output;
int delay;
int last_amp;
int phase;
int amp; // only used by saw
int period() const
{
return (regs [2] & 0x0F) * 0x100L + regs [1] + 1;
}
};
Vrc6_Osc oscs [osc_count];
blip_time_t last_time;
Blip_Synth<blip_med_quality,1> saw_synth;
Blip_Synth<blip_good_quality,1> square_synth;
void run_until( blip_time_t );
void run_square( Vrc6_Osc& osc, blip_time_t );
void run_saw( blip_time_t );
};
struct vrc6_apu_state_t
{
BOOST::uint8_t regs [3] [3];
BOOST::uint8_t saw_amp;
BOOST::uint16_t delays [3];
BOOST::uint8_t phases [3];
BOOST::uint8_t unused;
};
inline void Nes_Vrc6_Apu::osc_output( int i, Blip_Buffer* buf )
{
assert( (unsigned) i < osc_count );
oscs [i].output = buf;
}
inline void Nes_Vrc6_Apu::volume( double v )
{
double const factor = 0.0967 * 2;
saw_synth.volume( factor / 31 * v );
square_synth.volume( factor * 0.5 / 15 * v );
}
inline void Nes_Vrc6_Apu::treble_eq( blip_eq_t const& eq )
{
saw_synth.treble_eq( eq );
square_synth.treble_eq( eq );
}
#endif