AxibugEmuOnline/AxibugEmuOnline.Client/Assets/VirtualNes.Core/ApuEX/APU_VRC6.cs

311 lines
9.3 KiB
C#

using System;
namespace VirtualNes.Core
{
public class APU_VRC6 : APU_INTERFACE
{
public const int RECTANGLE_VOL_SHIFT = 8;
public const int SAWTOOTH_VOL_SHIFT = 6;
private RECTANGLE ch0 = new RECTANGLE();
private RECTANGLE ch1 = new RECTANGLE();
private SAWTOOTH ch2 = new SAWTOOTH();
private int cycle_rate;
private float cpu_clock;
public APU_VRC6()
{
Reset(APU_CLOCK, 22050);
}
public override void Reset(float fClock, int nRate)
{
ch0.ZeroMemory();
ch1.ZeroMemory();
ch2.ZeroMemory();
Setup(fClock, nRate);
}
public override void Setup(float fClock, int nRate)
{
cpu_clock = fClock;
cycle_rate = (int)(fClock * 65536.0f / nRate);
}
public override void Write(ushort addr, byte data)
{
switch (addr)
{
// VRC6 CH0 rectangle
case 0x9000:
ch0.reg[0] = data;
ch0.gate = (byte)(data & 0x80);
ch0.volume = (byte)(data & 0x0F);
ch0.duty_pos = (byte)((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 = (byte)(data & 0x80);
ch0.freq = INT2FIX((((data & 0x0F) << 8) | ch0.reg[1]) + 1);
break;
// VRC6 CH1 rectangle
case 0xA000:
ch1.reg[0] = data;
ch1.gate = (byte)(data & 0x80);
ch1.volume = (byte)(data & 0x0F);
ch1.duty_pos = (byte)((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 = (byte)(data & 0x80);
ch1.freq = INT2FIX((((data & 0x0F) << 8) | ch1.reg[1]) + 1);
break;
// VRC6 CH2 sawtooth
case 0xB000:
ch2.reg[1] = data;
ch2.phaseaccum = (byte)(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 = (byte)(data & 0x80);
ch2.freq = INT2FIX((((data & 0x0F) << 8) | ch2.reg[1]) + 1);
// ch2.adder = 0; // 僋儕傾偡傞偲僲僀僘偺尨場偵側傞
// ch2.accum = 0; // 僋儕傾偡傞偲僲僀僘偺尨場偵側傞
break;
}
}
public override int Process(int channel)
{
switch (channel)
{
case 0:
return RectangleRender(ch0);
case 1:
return RectangleRender(ch1);
case 2:
return SawtoothRender(ch2);
}
return 0;
}
public override int GetFreq(int channel)
{
if (channel == 0 || channel == 1)
{
RECTANGLE ch = null;
if (channel == 0) ch = ch0;
else ch = ch1;
if (ch.enable == 0 || ch.gate != 0 || ch.volume == 0)
return 0;
if (ch.freq < INT2FIX(8))
return 0;
return (int)(256.0f * cpu_clock / (FIX2INT(ch.freq) * 16.0f));
}
if (channel == 2)
{
SAWTOOTH ch = ch2;
if (ch.enable == 0 || ch.phaseaccum == 0)
return 0;
if (ch.freq < INT2FIX(8))
return 0;
return (int)(256.0f * cpu_clock / (FIX2INT(ch.freq) * 14.0f));
}
return 0;
}
private int RectangleRender(RECTANGLE ch)
{
// Enable?
if (ch.enable == 0)
{
ch.output_vol = 0;
ch.adder = 0;
return ch.output_vol;
}
// Digitized output
if (ch.gate != 0)
{
ch.output_vol = ch.volume << RECTANGLE_VOL_SHIFT;
return ch.output_vol;
}
// 堦掕埲忋偺廃攇悢偼張棟偟側偄(柍懯)
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 = (byte)((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 = (byte)((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;
}
private int SawtoothRender(SAWTOOTH ch)
{
// Digitized output
if (ch.enable == 0)
{
ch.output_vol = 0;
return ch.output_vol;
}
// 堦掕埲忋偺廃攇悢偼張棟偟側偄(柍懯)
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;
}
public class RECTANGLE
{
public byte[] reg = new byte[3];
public byte enable;
public byte gate;
public byte volume;
public int phaseacc;
public int freq;
public int output_vol;
public byte adder;
public byte duty_pos;
public void ZeroMemory()
{
Array.Clear(reg, 0, reg.Length);
enable = 0;
gate = 0;
volume = 0;
phaseacc = 0;
freq = 0;
output_vol = 0;
adder = 0;
duty_pos = 0;
}
}
public class SAWTOOTH
{
public byte[] reg = new byte[3];
public byte enable;
public byte volume;
public int phaseacc;
public int freq;
public int output_vol;
public byte adder;
public byte accum;
public byte phaseaccum;
public void ZeroMemory()
{
Array.Clear(reg, 0, reg.Length);
enable = 0;
volume = 0;
phaseacc = 0;
freq = 0;
output_vol = 0;
adder = 0;
accum = 0;
phaseaccum = 0;
}
}
}
}