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
        {
                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
{
        uint8_t regs [3] [3];
        uint8_t saw_amp;
        uint16_t delays [3];
        uint8_t phases [3];
        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