AxibugEmuOnline/References/virtuanessrc097-master/NES/ApuEX/APU_VRC6.cpp
2024-08-05 17:58:53 +08:00

253 lines
11 KiB
C++
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

//////////////////////////////////////////////////////////////////////////
// //
// Konami VRC6 //
// Norix //
// written 2001/09/18 //
// last modify ----/--/-- //
//////////////////////////////////////////////////////////////////////////
#include "APU_VRC6.h"
#include "state.h"
#define RECTANGLE_VOL_SHIFT 8
#define SAWTOOTH_VOL_SHIFT 6
APU_VRC6::APU_VRC6()
{
// 仮設定
Reset( APU_CLOCK, 22050 );
}
APU_VRC6::~APU_VRC6()
{
}
void APU_VRC6::Reset( FLOAT fClock, INT nRate )
{
ZeroMemory( &ch0, sizeof(ch0) );
ZeroMemory( &ch1, sizeof(ch1) );
ZeroMemory( &ch2, sizeof(ch2) );
Setup( fClock, nRate );
}
void APU_VRC6::Setup( FLOAT fClock, INT nRate )
{
cpu_clock = fClock;
cycle_rate = (INT)(fClock*65536.0f/(float)nRate);
}
void APU_VRC6::Write( WORD addr, BYTE data )
{
switch( addr ) {
// VRC6 CH0 rectangle
case 0x9000:
ch0.reg[0] = data;
ch0.gate = data&0x80;
ch0.volume = data&0x0F;
ch0.duty_pos = (data>>4)&0x07;
break;
case 0x9001:
ch0.reg[1] = data;
ch0.freq = INT2FIX( (((ch0.reg[2]&0x0F)<<8)|data)+1 );
break;
case 0x9002:
ch0.reg[2] = data;
ch0.enable = data&0x80;
ch0.freq = INT2FIX( (((data&0x0F)<<8)|ch0.reg[1])+1 );
break;
// VRC6 CH1 rectangle
case 0xA000:
ch1.reg[0] = data;
ch1.gate = data&0x80;
ch1.volume = data&0x0F;
ch1.duty_pos = (data>>4)&0x07;
break;
case 0xA001:
ch1.reg[1] = data;
ch1.freq = INT2FIX( (((ch1.reg[2]&0x0F)<<8)|data)+1 );
break;
case 0xA002:
ch1.reg[2] = data;
ch1.enable = data&0x80;
ch1.freq = INT2FIX( (((data&0x0F)<<8)|ch1.reg[1])+1 );
break;
// VRC6 CH2 sawtooth
case 0xB000:
ch2.reg[1] = data;
ch2.phaseaccum = data&0x3F;
break;
case 0xB001:
ch2.reg[1] = data;
ch2.freq = INT2FIX( (((ch2.reg[2]&0x0F)<<8)|data)+1 );
break;
case 0xB002:
ch2.reg[2] = data;
ch2.enable = data&0x80;
ch2.freq = INT2FIX( (((data&0x0F)<<8)|ch2.reg[1])+1 );
// ch2.adder = 0; // クリアするとノイズの原因になる
// ch2.accum = 0; // クリアするとノイズの原因になる
break;
}
}
INT APU_VRC6::Process( INT channel )
{
switch( channel ) {
case 0:
return RectangleRender( ch0 );
break;
case 1:
return RectangleRender( ch1 );
break;
case 2:
return SawtoothRender( ch2 );
break;
}
return 0;
}
INT APU_VRC6::GetFreq( INT channel )
{
if( channel == 0 || channel == 1 ) {
RECTANGLE* ch;
if( channel == 0 ) ch = &ch0;
else ch = &ch1;
if( !ch->enable || ch->gate || !ch->volume )
return 0;
if( ch->freq < INT2FIX( 8 ) )
return 0;
return (INT)(256.0f*cpu_clock/((FLOAT)FIX2INT(ch->freq)*16.0f));
}
if( channel == 2 ) {
SAWTOOTH* ch = &ch2;
if( !ch->enable || !ch->phaseaccum )
return 0;
if( ch->freq < INT2FIX( 8 ) )
return 0;
return (INT)(256.0f*cpu_clock/((FLOAT)FIX2INT(ch->freq)*14.0f));
}
return 0;
}
INT APU_VRC6::RectangleRender( RECTANGLE& ch )
{
// Enable?
if( !ch.enable ) {
ch.output_vol = 0;
ch.adder = 0;
return ch.output_vol;
}
// Digitized output
if( ch.gate ) {
ch.output_vol = ch.volume<<RECTANGLE_VOL_SHIFT;
return ch.output_vol;
}
// 一定以上の周波数は処理しない(無駄)
if( ch.freq < INT2FIX( 8 ) ) {
ch.output_vol = 0;
return ch.output_vol;
}
ch.phaseacc -= cycle_rate;
if( ch.phaseacc >= 0 )
return ch.output_vol;
INT output = ch.volume<<RECTANGLE_VOL_SHIFT;
if( ch.freq > cycle_rate ) {
// add 1 step
ch.phaseacc += ch.freq;
ch.adder = (ch.adder+1)&0x0F;
if( ch.adder <= ch.duty_pos )
ch.output_vol = output;
else
ch.output_vol = -output;
} else {
// average calculate
INT num_times, total;
num_times = total = 0;
while( ch.phaseacc < 0 ) {
ch.phaseacc += ch.freq;
ch.adder = (ch.adder+1)&0x0F;
if( ch.adder <= ch.duty_pos )
total += output;
else
total += -output;
num_times++;
}
ch.output_vol = total/num_times;
}
return ch.output_vol;
}
INT APU_VRC6::SawtoothRender( SAWTOOTH& ch )
{
// Digitized output
if( !ch.enable ) {
ch.output_vol = 0;
return ch.output_vol;
}
// 一定以上の周波数は処理しない(無駄)
if( ch.freq < INT2FIX( 9 ) ) {
return ch.output_vol;
}
ch.phaseacc -= cycle_rate/2;
if( ch.phaseacc >= 0 )
return ch.output_vol;
if( ch.freq > cycle_rate/2 ) {
// add 1 step
ch.phaseacc += ch.freq;
if( ++ch.adder >= 7 ) {
ch.adder = 0;
ch.accum = 0;
}
ch.accum += ch.phaseaccum;
ch.output_vol = ch.accum<<SAWTOOTH_VOL_SHIFT;
} else {
// average calculate
INT num_times, total;
num_times = total = 0;
while( ch.phaseacc < 0 ) {
ch.phaseacc += ch.freq;
if( ++ch.adder >= 7 ) {
ch.adder = 0;
ch.accum = 0;
}
ch.accum += ch.phaseaccum;
total += ch.accum<<SAWTOOTH_VOL_SHIFT;
num_times++;
}
ch.output_vol = (total/num_times);
}
return ch.output_vol;
}
INT APU_VRC6::GetStateSize()
{
return sizeof(ch0) + sizeof(ch1) + sizeof(ch2);
}
void APU_VRC6::SaveState( LPBYTE p )
{
SETBLOCK( p, &ch0, sizeof(ch0) );
SETBLOCK( p, &ch1, sizeof(ch1) );
SETBLOCK( p, &ch2, sizeof(ch2) );
}
void APU_VRC6::LoadState( LPBYTE p )
{
GETBLOCK( p, &ch0, sizeof(ch0) );
GETBLOCK( p, &ch1, sizeof(ch1) );
GETBLOCK( p, &ch2, sizeof(ch2) );
}