63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
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// Konami VRC6 sound chip emulator
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// Nes_Snd_Emu 0.1.8
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#ifndef NES_VRC6_APU_H
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#define NES_VRC6_APU_H
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#include "blargg_common.h"
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#include "blip_buffer.h"
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enum { vrc6_osc_count = 3 };
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enum { vrc6_reg_count = 3 };
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enum { vrc6_base_addr = 0x9000 };
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enum { vrc6_addr_step = 0x1000 };
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struct Vrc6_Osc
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{
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uint8_t regs [vrc6_reg_count];
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struct Blip_Buffer* output;
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int delay;
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int last_amp;
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int phase;
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int amp; // only used by saw
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};
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static inline int Vrc6_osc_period( struct Vrc6_Osc* this )
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{
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return (this->regs [2] & 0x0F) * 0x100 + this->regs [1] + 1;
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}
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struct Nes_Vrc6_Apu {
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struct Vrc6_Osc oscs [vrc6_osc_count];
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blip_time_t last_time;
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struct Blip_Synth saw_synth;
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struct Blip_Synth square_synth;
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};
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// See Nes_Apu.h for reference
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void Vrc6_init( struct Nes_Vrc6_Apu* this );
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void Vrc6_reset( struct Nes_Vrc6_Apu* this );
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void Vrc6_output( struct Nes_Vrc6_Apu* this, struct Blip_Buffer* );
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void Vrc6_end_frame( struct Nes_Vrc6_Apu* this, blip_time_t ) ICODE_ATTR;
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// Oscillator 0 write-only registers are at $9000-$9002
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// Oscillator 1 write-only registers are at $A000-$A002
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// Oscillator 2 write-only registers are at $B000-$B002
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void Vrc6_write_osc( struct Nes_Vrc6_Apu* this, blip_time_t, int osc, int reg, int data ) ICODE_ATTR;
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static inline void Vrc6_osc_output( struct Nes_Vrc6_Apu* this, int i, struct Blip_Buffer* buf )
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{
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assert( (unsigned) i < vrc6_osc_count );
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this->oscs [i].output = buf;
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}
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static inline void Vrc6_volume( struct Nes_Vrc6_Apu* this, double v )
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{
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double const factor = 0.0967 * 2;
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Synth_volume( &this->saw_synth, factor / 31 * v );
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Synth_volume( &this->square_synth, factor * 0.5 / 15 * v );
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}
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#endif
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