130 lines
2.5 KiB
C++
130 lines
2.5 KiB
C++
// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
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// NES FDS sound chip emulator
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#ifndef NES_FDS_APU_H
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#define NES_FDS_APU_H
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#include "blargg_common.h"
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#include "Blip_Buffer.h"
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class Nes_Fds_Apu {
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public:
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// setup
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void set_tempo( double );
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enum { osc_count = 1 };
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void volume( double );
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void treble_eq( blip_eq_t const& eq ) { synth.treble_eq( eq ); }
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// emulation
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void reset();
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enum { io_addr = 0x4040 };
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enum { io_size = 0x53 };
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void write( blip_time_t time, unsigned addr, int data );
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int read( blip_time_t time, unsigned addr );
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void end_frame( blip_time_t );
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public:
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Nes_Fds_Apu();
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void write_( unsigned addr, int data );
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BLARGG_DISABLE_NOTHROW
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void osc_output( int, Blip_Buffer* );
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private:
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enum { wave_size = 0x40 };
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enum { master_vol_max = 10 };
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enum { vol_max = 0x20 };
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enum { wave_sample_max = 0x3F };
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unsigned char regs_ [io_size];// last written value to registers
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enum { lfo_base_tempo = 8 };
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int lfo_tempo; // normally 8; adjusted by set_tempo()
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int env_delay;
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int env_speed;
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int env_gain;
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int sweep_delay;
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int sweep_speed;
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int sweep_gain;
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int wave_pos;
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int last_amp;
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blip_time_t wave_fract;
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int mod_fract;
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int mod_pos;
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int mod_write_pos;
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unsigned char mod_wave [wave_size];
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// synthesis
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blip_time_t last_time;
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Blip_Buffer* output_;
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Blip_Synth<blip_med_quality,1> synth;
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// allow access to registers by absolute address (i.e. 0x4080)
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unsigned char& regs( unsigned addr ) { return regs_ [addr - io_addr]; }
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void run_until( blip_time_t );
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};
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inline void Nes_Fds_Apu::volume( double v )
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{
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synth.volume( 0.14 / master_vol_max / vol_max / wave_sample_max * v );
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}
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inline void Nes_Fds_Apu::osc_output( int i, Blip_Buffer* buf )
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{
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assert( (unsigned) i < osc_count );
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output_ = buf;
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}
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inline void Nes_Fds_Apu::end_frame( blip_time_t end_time )
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{
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if ( end_time > last_time )
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run_until( end_time );
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last_time -= end_time;
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assert( last_time >= 0 );
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}
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inline void Nes_Fds_Apu::write( blip_time_t time, unsigned addr, int data )
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{
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run_until( time );
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write_( addr, data );
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}
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inline int Nes_Fds_Apu::read( blip_time_t time, unsigned addr )
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{
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run_until( time );
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int result = 0xFF;
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switch ( addr )
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{
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case 0x4090:
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result = env_gain;
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break;
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case 0x4092:
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result = sweep_gain;
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break;
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default:
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unsigned i = addr - io_addr;
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if ( i < wave_size )
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result = regs_ [i];
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}
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return result | 0x40;
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}
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inline Nes_Fds_Apu::Nes_Fds_Apu()
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{
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lfo_tempo = lfo_base_tempo;
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osc_output( 0, NULL );
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volume( 1.0 );
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reset();
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}
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#endif
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