Path: blob/master/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/FDS/FDSAudio.cs
2 views
using System;
using BizHawk.Common;
namespace BizHawk.Emulation.Cores.Nintendo.NES
{
// http://wiki.nesdev.com/w/index.php/FDS_audio
public class FDSAudio
{
public void SyncState(Serializer ser)
{
ser.Sync("waveram", ref waveram, false);
ser.Sync("waverampos", ref waverampos);
ser.Sync("volumespd", ref volumespd);
ser.Sync("r4080_6", ref r4080_6);
ser.Sync("r4080_7", ref r4080_7);
ser.Sync("frequency", ref frequency);
ser.Sync("r4083_6", ref r4083_6);
ser.Sync("r4083_7", ref r4083_7);
ser.Sync("sweepspd", ref sweepspd);
ser.Sync("r4084_6", ref r4084_6);
ser.Sync("r4084_7", ref r4084_7);
ser.Sync("sweepbias", ref sweepbias);
ser.Sync("modfreq", ref modfreq);
ser.Sync("r4087_7", ref r4087_7);
ser.Sync("modtable", ref modtable, false);
ser.Sync("modtablepos", ref modtablepos);
ser.Sync("mastervol_num", ref mastervol_num);
ser.Sync("mastervol_den", ref mastervol_den);
ser.Sync("waveram_writeenable", ref waveram_writeenable);
ser.Sync("envspeed", ref envspeed);
ser.Sync("volumeclock", ref volumeclock);
ser.Sync("sweepclock", ref sweepclock);
ser.Sync("modclock", ref modclock);
ser.Sync("mainclock", ref mainclock);
ser.Sync("modoutput", ref modoutput);
ser.Sync("volumegain", ref volumegain);
ser.Sync("sweepgain", ref sweepgain);
ser.Sync("waveramoutput", ref waveramoutput);
ser.Sync("latchedoutput", ref latchedoutput);
}
//4040:407f
byte[] waveram = new byte[64];
/// <summary>
/// playback position, clocked by main unit
/// </summary>
int waverampos;
//4080
/// <summary>
/// volume level or envelope speed, depending on r4080_7
/// </summary>
int volumespd;
/// <summary>
/// increase volume with envelope
/// </summary>
bool r4080_6;
/// <summary>
/// disable volume envelope
/// </summary>
bool r4080_7;
//4082:4083
/// <summary>
/// speed to clock main unit
/// </summary>
int frequency;
/// <summary>
/// disable volume and sweep
/// </summary>
bool r4083_6;
/// <summary>
/// silence channel
/// </summary>
bool r4083_7;
//4084
/// <summary>
/// sweep gain or sweep speed, depending on r4084_7
/// </summary>
int sweepspd;
/// <summary>
/// increase sweep with envelope
/// </summary>
bool r4084_6;
/// <summary>
/// disable sweep unit
/// </summary>
bool r4084_7;
//4085
/// <summary>
/// 7 bit signed
/// </summary>
int sweepbias;
//4086:4087
/// <summary>
/// speed to clock modulation unit
/// </summary>
int modfreq;
/// <summary>
/// disable modulation unit
/// </summary>
bool r4087_7;
//4088
/// <summary>
/// ring buffer, only 32 entries on hardware
/// </summary>
byte[] modtable = new byte[64];
/// <summary>
/// playback position
/// </summary>
int modtablepos;
//4089
int mastervol_num = 1;
int mastervol_den = 1;
/// <summary>
/// channel silenced and waveram writable
/// </summary>
bool waveram_writeenable;
//408a
int envspeed;
int volumeclock;
int sweepclock;
int modclock;
int mainclock;
int modoutput;
// read at 4090
int volumegain;
// read at 4092
int sweepgain;
int waveramoutput;
int latchedoutput;
Action<int> SendDiff;
public FDSAudio(Action<int> SendDiff)
{
this.SendDiff = SendDiff;
}
void CalcMod()
{
// http://forums.nesdev.com/viewtopic.php?f=3&t=10233
int tmp = sweepbias * sweepgain;
int remainder = tmp & 15;
tmp >>= 4;
if (remainder > 0 && (tmp & 0x80) == 0)
{
if (sweepbias < 0)
tmp -= 1;
else
tmp += 2;
}
// signed with unconventional bias
if (tmp >= 192)
tmp -= 256;
else if (tmp < -64)
tmp += 256;
// round to nearest
tmp *= frequency;
remainder = tmp & 63;
tmp >>= 6;
if (remainder >= 32)
tmp++;
modoutput = tmp;
}
void CalcOut()
{
int tmp = volumegain < 32 ? volumegain : 32;
tmp *= waveramoutput;
tmp *= mastervol_num;
tmp /= mastervol_den;
if (latchedoutput != tmp)
{
SendDiff((tmp - latchedoutput) * 3);
latchedoutput = tmp;
}
}
/// <summary>
/// ~1.7mhz
/// </summary>
public void Clock()
{
// volume envelope unit
if (!r4080_7 && envspeed > 0 && !r4083_6)
{
volumeclock++;
if (volumeclock >= 8 * envspeed * (volumespd + 1))
{
volumeclock = 0;
if (r4080_6 && volumegain < 32)
volumegain++;
else if (!r4080_6 && volumegain > 0)
volumegain--;
CalcOut();
}
}
// sweep unit
if (!r4084_7 && envspeed > 0 && !r4083_6)
{
sweepclock++;
if (sweepclock >= 8 * envspeed * (sweepspd + 1))
{
sweepclock = 0;
if (r4084_6 && sweepgain < 32)
sweepgain++;
else if (!r4084_6 && sweepgain > 0)
sweepgain--;
CalcMod();
}
}
// modulation unit
if (!r4087_7 && modfreq > 0)
{
modclock += modfreq;
if (modclock >= 0x10000)
{
modclock -= 0x10000;
// our modtable is really twice as big (64 entries)
switch (modtable[modtablepos++])
{
case 0: sweepbias += 0; break;
case 1: sweepbias += 1; break;
case 2: sweepbias += 2; break;
case 3: sweepbias += 4; break;
case 4: sweepbias = 0; break;
case 5: sweepbias -= 4; break;
case 6: sweepbias -= 2; break;
case 7: sweepbias -= 1; break;
}
// sign extend
sweepbias <<= 25;
sweepbias >>= 25;
modtablepos &= 63;
CalcMod();
}
}
// main unit
if (!r4083_7 && frequency > 0 && frequency + modoutput > 0 && !waveram_writeenable)
{
mainclock += frequency + modoutput;
if (mainclock >= 0x10000)
{
mainclock -= 0x10000;
waveramoutput = waveram[waverampos++];
waverampos &= 63;
CalcOut();
}
}
}
public void WriteReg(int addr, byte value)
{
if (addr < 0x4080)
{
if (waveram_writeenable)
waveram[addr - 0x4040] = (byte)(value & 63);
return;
}
switch (addr)
{
case 0x4080:
r4080_6 = (value & 0x40) != 0;
r4080_7 = (value & 0x80) != 0;
volumeclock = 0;
volumespd = value & 63;
if (r4080_7) // envelope is off, so written value gets sent to gain directly
volumegain = value & 63;
break;
case 0x4082:
frequency &= 0xf00;
frequency |= value;
break;
case 0x4083:
frequency &= 0x0ff;
frequency |= value << 8 & 0xf00;
r4083_6 = (value & 0x40) != 0;
r4083_7 = (value & 0x80) != 0;
if (r4083_7)
waverampos = 0;
if (r4083_6)
{
volumeclock = 0;
sweepclock = 0;
}
break;
case 0x4084:
sweepspd = value & 63;
r4084_6 = (value & 0x40) != 0;
r4084_7 = (value & 0x80) != 0;
sweepclock = 0;
if (r4084_7)
sweepgain = value & 63;
break;
case 0x4085:
sweepbias = value & 0x7f;
// sign extend
sweepbias <<= 25;
sweepbias >>= 25;
break;
case 0x4086:
modfreq &= 0xf00;
modfreq |= value;
if (r4087_7 || modfreq == 0) // when mod unit is disabled, mod output is fixed to 0, not hanging
modoutput = 0;
break;
case 0x4087:
modfreq &= 0x0ff;
modfreq |= value << 8 & 0xf00;
r4087_7 = (value & 0x80) != 0;
if (r4087_7 || modfreq == 0) // when mod unit is disabled, mod output is fixed to 0, not hanging
modoutput = 0;
if (r4087_7)
modclock = 0;
break;
case 0x4088:
// write twice into virtual 64 unit buffer
if (r4087_7)
{
modtable[modtablepos] = (byte)(value & 7);
modtablepos++;
modtablepos &= 63;
modtable[modtablepos] = (byte)(value & 7);
modtablepos++;
modtablepos &= 63;
}
break;
case 0x4089:
switch (value & 3)
{
case 0: mastervol_num = 1; mastervol_den = 1; break;
case 1: mastervol_num = 2; mastervol_den = 3; break;
case 2: mastervol_num = 2; mastervol_den = 4; break;
case 3: mastervol_num = 2; mastervol_den = 5; break;
}
waveram_writeenable = (value & 0x80) != 0;
break;
case 0x408a:
envspeed = value;
break;
}
}
public byte ReadReg(int addr, byte openbus)
{
byte ret = openbus;
if (addr < 0x4080)
{
ret &= 0xc0;
ret |= waveram[addr - 0x4040];
}
else if (addr == 0x4090)
{
ret &= 0xc0;
ret |= (byte)volumegain;
}
else if (addr == 0x4092)
{
ret &= 0xc0;
ret |= (byte)sweepgain;
}
return ret;
}
}
}