90 lines
2 KiB
C
90 lines
2 KiB
C
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#include "nes_vrc7_apu.h"
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#include "blargg_source.h"
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int const period = 36; // NES CPU clocks per FM clock
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void Vrc7_init( struct Nes_Vrc7_Apu* this )
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{
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Synth_init( &this->synth );
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OPLL_new ( &this->opll, 3579545, 3579545 / 72 );
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OPLL_reset_patch( &this->opll, OPLL_VRC7_TONE );
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this->osc.output = 0;
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this->osc.last_amp = 0;
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this->mask = 0;
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Vrc7_volume( this, 1.0 );
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Vrc7_reset( this );
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}
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void Vrc7_reset( struct Nes_Vrc7_Apu* this )
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{
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this->addr = 0;
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this->next_time = 0;
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this->osc.last_amp = 0;
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OPLL_reset (&this->opll);
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OPLL_setMask(&this->opll, this->mask);
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}
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void Vrc7_set_rate( struct Nes_Vrc7_Apu* this, double r )
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{
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OPLL_set_quality( &this->opll, r < 44100 ? 0 : 1 );
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OPLL_set_rate( &this->opll, (e_uint32)r );
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}
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void Vrc7_write_reg( struct Nes_Vrc7_Apu* this, int data )
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{
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this->addr = data;
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}
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void Vrc7_run_until( struct Nes_Vrc7_Apu* this, blip_time_t end_time );
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void Vrc7_write_data( struct Nes_Vrc7_Apu* this, blip_time_t time, int data )
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{
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if ( time > this->next_time )
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Vrc7_run_until( this, time );
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OPLL_writeIO( &this->opll, 0, this->addr );
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OPLL_writeIO( &this->opll, 1, data );
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}
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void Vrc7_end_frame( struct Nes_Vrc7_Apu* this, blip_time_t time )
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{
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if ( time > this->next_time )
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Vrc7_run_until( this, time );
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this->next_time -= time;
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assert( this->next_time >= 0 );
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if ( this->osc.output )
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Blip_set_modified( this->osc.output );
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}
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void Vrc7_run_until( struct Nes_Vrc7_Apu* this, blip_time_t end_time )
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{
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require( end_time > this->next_time );
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blip_time_t time = this->next_time;
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OPLL* opll = &this->opll; // cache
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struct Blip_Buffer* const output = this-> osc.output;
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if ( output )
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{
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do
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{
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int amp = OPLL_calc( opll ) << 1;
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int delta = amp - this->osc.last_amp;
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if ( delta )
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{
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this->osc.last_amp = amp;
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Synth_offset_inline( &this->synth, time, delta, output );
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}
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time += period;
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}
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while ( time < end_time );
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}
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this->next_time = time;
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}
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