raze/libraries/game-music-emu/gme/Nes_Fme7_Apu.h

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// Sunsoft FME-7 sound emulator
// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
#ifndef NES_FME7_APU_H
#define NES_FME7_APU_H
#include "blargg_common.h"
#include "Blip_Buffer.h"
struct fme7_apu_state_t
{
enum { reg_count = 14 };
uint8_t regs [reg_count];
uint8_t phases [3]; // 0 or 1
uint8_t latch;
uint16_t delays [3]; // a, b, c
};
class Nes_Fme7_Apu : private fme7_apu_state_t {
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( fme7_apu_state_t* ) const;
void load_state( fme7_apu_state_t const& );
// Mask and addresses of registers
enum { addr_mask = 0xE000 };
enum { data_addr = 0xE000 };
enum { latch_addr = 0xC000 };
// (addr & addr_mask) == latch_addr
void write_latch( int );
// (addr & addr_mask) == data_addr
void write_data( blip_time_t, int data );
public:
Nes_Fme7_Apu();
BLARGG_DISABLE_NOTHROW
private:
// noncopyable
Nes_Fme7_Apu( const Nes_Fme7_Apu& );
Nes_Fme7_Apu& operator = ( const Nes_Fme7_Apu& );
static unsigned char const amp_table [16];
struct {
Blip_Buffer* output;
int last_amp;
} oscs [osc_count];
blip_time_t last_time;
enum { amp_range = 192 }; // can be any value; this gives best error/quality tradeoff
Blip_Synth<blip_good_quality,1> synth;
void run_until( blip_time_t );
};
inline void Nes_Fme7_Apu::volume( double v )
{
synth.volume( 0.38 / amp_range * v ); // to do: fine-tune
}
inline void Nes_Fme7_Apu::treble_eq( blip_eq_t const& eq )
{
synth.treble_eq( eq );
}
inline void Nes_Fme7_Apu::osc_output( int i, Blip_Buffer* buf )
{
assert( (unsigned) i < osc_count );
oscs [i].output = buf;
}
inline void Nes_Fme7_Apu::output( Blip_Buffer* buf )
{
for ( int i = 0; i < osc_count; i++ )
osc_output( i, buf );
}
inline Nes_Fme7_Apu::Nes_Fme7_Apu()
{
output( NULL );
volume( 1.0 );
reset();
}
inline void Nes_Fme7_Apu::write_latch( int data ) { latch = data; }
inline void Nes_Fme7_Apu::write_data( blip_time_t time, int data )
{
if ( (unsigned) latch >= reg_count )
{
#ifdef debug_printf
debug_printf( "FME7 write to %02X (past end of sound registers)\n", (int) latch );
#endif
return;
}
run_until( time );
regs [latch] = data;
}
inline void Nes_Fme7_Apu::end_frame( blip_time_t time )
{
if ( time > last_time )
run_until( time );
assert( last_time >= time );
last_time -= time;
}
inline void Nes_Fme7_Apu::save_state( fme7_apu_state_t* out ) const
{
*out = *this;
}
inline void Nes_Fme7_Apu::load_state( fme7_apu_state_t const& in )
{
reset();
fme7_apu_state_t* state = this;
*state = in;
}
#endif