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ValleyBell merged 1 commit into from
Jul 14, 2025
Merged

VSU: Improve accuracy #142

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154 changes: 99 additions & 55 deletions emu/cores/vsu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,8 @@ typedef struct
UINT8 ModData[0x20];

INT32 EffFreq[6];
INT32 Envelope[6];
INT32 EnvelopeValue[6];
INT32 EnvelopeReload[6];

UINT8 WavePos[6];
UINT8 ModWavePos;
Expand All @@ -128,6 +129,10 @@ typedef struct
INT32 EnvelopeClockDivider[6];
INT32 SweepModClockDivider;

INT32 EnvelopeModMask[6];
INT32 ModState;
INT32 ModLock;

INT32 NoiseLatcherClockDivider;
UINT8 NoiseLatcher;

Expand Down Expand Up @@ -155,6 +160,8 @@ static void VSU_Power(vsu_state* chip)
chip->SweepControl = 0;
chip->SweepModCounter = 0;
chip->SweepModClockDivider = 1;
chip->ModState = 0;
chip->ModLock = 0;

for(ch = 0; ch < 6; ch++)
{
Expand All @@ -166,7 +173,9 @@ static void VSU_Power(vsu_state* chip)
chip->RAMAddress[ch] = 0;

chip->EffFreq[ch] = 0;
chip->Envelope[ch] = 0;
chip->EnvelopeReload[ch] = 0;
chip->EnvelopeValue[ch] = 0;
chip->EnvelopeModMask[ch] = 0;
chip->WavePos[ch] = 0;
chip->FreqCounter[ch] = 0;
chip->IntervalCounter[ch] = 0;
Expand Down Expand Up @@ -196,15 +205,25 @@ static void VSU_Write(void* info, UINT16 A, UINT8 V)
A <<= 2;
A &= 0x7FF;

chip->ModLock = 0;

//printf("VSU Write: %d, %08x %02x\n", timestamp, A, V);

if(A < 0x280)
chip->WaveData[A >> 7][(A >> 2) & 0x1F] = V & 0x3F;
{
bool cancel_write = false;
for(int i = 0; i < 6; i++)
if(chip->IntlControl[i] & 0x80)
cancel_write = true;
if(!cancel_write)
chip->WaveData[A >> 7][(A >> 2) & 0x1F] = V & 0x3F;
}
else if(A < 0x400)
{
//if(A >= 0x300)
// printf("Modulation mirror write? %08x %02x\n", A, V);
chip->ModData[(A >> 2) & 0x1F] = V;
if(!(chip->IntlControl[4] & 0x80))
chip->ModData[(A >> 2) & 0x1F] = V;
}
else if(A < 0x600)
{
Expand All @@ -231,7 +250,6 @@ static void VSU_Write(void* info, UINT16 A, UINT8 V)

if(V & 0x80)
{
chip->EffFreq[ch] = chip->Frequency[ch];
if(ch == 5)
chip->FreqCounter[ch] = 10 * (2048 - chip->EffFreq[ch]);
else
Expand All @@ -244,15 +262,21 @@ static void VSU_Write(void* info, UINT16 A, UINT8 V)
chip->SweepModCounter = (chip->SweepControl >> 4) & 7;
chip->SweepModClockDivider = (chip->SweepControl & 0x80) ? 8 : 1;
chip->ModWavePos = 0;
chip->ModState = 0;
}

chip->WavePos[ch] = 0;

if(ch == 5)
chip->lfsr = 1;

//if(!(chip->IntlControl[ch] & 0x80))
// chip->Envelope[ch] = (chip->EnvControl[ch] >> 4) & 0xF;
chip->EnvelopeModMask[ch] = 0;
if(!(chip->EnvControl[ch] & 0x200) && (
(chip->EnvelopeValue[ch] == 0 && !(chip->EnvControl[ch] & 0x0008)) ||
(chip->EnvelopeValue[ch] == 0xF && (chip->EnvControl[ch] & 0x0008))))
{
chip->EnvelopeModMask[ch] = 1;
}

chip->EffectsClockDivider[ch] = 4800;
chip->IntervalClockDivider[ch] = 4;
Expand All @@ -270,30 +294,48 @@ static void VSU_Write(void* info, UINT16 A, UINT8 V)
chip->Frequency[ch] |= V << 0;
chip->EffFreq[ch] &= 0xFF00;
chip->EffFreq[ch] |= V << 0;
chip->ModLock = 1;
break;

case 0x3:
chip->Frequency[ch] &= 0x00FF;
chip->Frequency[ch] |= (V & 0x7) << 8;
chip->EffFreq[ch] &= 0x00FF;
chip->EffFreq[ch] |= (V & 0x7) << 8;
chip->ModLock = 2;
break;

case 0x4:
chip->EnvControl[ch] &= 0xFF00;
chip->EnvControl[ch] |= V << 0;

chip->Envelope[ch] = (V >> 4) & 0xF;
chip->EnvelopeReload[ch] = (V >> 4) & 0xF;
chip->EnvelopeValue[ch] = (V >> 4) & 0xF;

if(chip->EnvelopeModMask[ch] == 1)
{
chip->EnvelopeModMask[ch] = 2;
}
break;

case 0x5:
chip->EnvControl[ch] &= 0x00FF;
if(ch == 4)
chip->EnvControl[ch] |= (V & 0x73) << 8;
else if(ch == 5)
{
chip->EnvControl[ch] |= (V & 0x73) << 8;
chip->lfsr = 1;
}
else
chip->EnvControl[ch] |= (V & 0x03) << 8;

if(chip->EnvelopeModMask[ch] == 0 && !(chip->EnvControl[ch] & 0x200) && (
(chip->EnvelopeValue[ch] == 0 && !(chip->EnvControl[ch] & 0x0008)) ||
(chip->EnvelopeValue[ch] == 0xF && (chip->EnvControl[ch] & 0x0008))))
{
chip->EnvelopeModMask[ch] = 1;
}
break;

case 0x6:
Expand Down Expand Up @@ -327,14 +369,14 @@ INLINE void VSU_CalcCurrentOutput(vsu_state* chip, int ch, DEV_SMPL* left, DEV_S
else
WD = chip->WaveData[chip->RAMAddress[ch]][chip->WavePos[ch]];
}
l_ol = chip->Envelope[ch] * chip->LeftLevel[ch];
l_ol = chip->EnvelopeValue[ch] * chip->LeftLevel[ch];
if(l_ol)
{
l_ol >>= 3;
l_ol += 1;
}

r_ol = chip->Envelope[ch] * chip->RightLevel[ch];
r_ol = chip->EnvelopeValue[ch] * chip->RightLevel[ch];
if(r_ol)
{
r_ol >>= 3;
Expand Down Expand Up @@ -396,7 +438,7 @@ static void VSU_Update(vsu_state* chip, UINT32 clocks, DEV_SMPL* outleft, DEV_SM
{
if(ch == 5)
{
int feedback = ((chip->lfsr >> 7) & 1) ^ ((chip->lfsr >> Tap_LUT[(chip->EnvControl[5] >> 12) & 0x7]) & 1);
int feedback = ((chip->lfsr >> 7) & 1) ^ ((chip->lfsr >> Tap_LUT[(chip->EnvControl[5] >> 12) & 0x7]) & 1) ^ 1;
chip->lfsr = ((chip->lfsr << 1) & 0x7FFF) | feedback;

chip->FreqCounter[ch] += 10 * (2048 - chip->EffFreq[ch]);
Expand Down Expand Up @@ -446,23 +488,27 @@ static void VSU_Update(vsu_state* chip, UINT32 clocks, DEV_SMPL* outleft, DEV_SM
{
chip->EnvelopeClockDivider[ch] += 4;

INT32 new_envelope = chip->EnvelopeValue[ch];
if(chip->EnvelopeValue[ch] < 0xF &&(chip->EnvControl[ch] & 0x0008))
new_envelope++;
else if(chip->EnvelopeValue[ch] > 0 && !(chip->EnvControl[ch] & 0x0008))
new_envelope--;
else if((chip->EnvControl[ch] & 0x200) && chip->EnvelopeModMask[ch] != 2)
{
new_envelope = chip->EnvelopeReload[ch];
chip->EnvelopeModMask[ch] = 0;
}
else if(chip->EnvelopeModMask[ch] == 0)
chip->EnvelopeModMask[ch] = 1;

if(chip->EnvControl[ch] & 0x0100) // Enveloping enabled?
{
chip->EnvelopeCounter[ch]--;
if(!chip->EnvelopeCounter[ch])
{
chip->EnvelopeCounter[ch] = (chip->EnvControl[ch] & 0x7) + 1;

if(chip->EnvControl[ch] & 0x0008) // Grow
{
if(chip->Envelope[ch] < 0xF || (chip->EnvControl[ch] & 0x200))
chip->Envelope[ch] = (chip->Envelope[ch] + 1) & 0xF;
}
else // Decay
{
if(chip->Envelope[ch] > 0 || (chip->EnvControl[ch] & 0x200))
chip->Envelope[ch] = (chip->Envelope[ch] - 1) & 0xF;
}
if(chip->EnvelopeModMask[ch] == 0)
chip->EnvelopeValue[ch] = new_envelope;
}
}

Expand All @@ -471,6 +517,18 @@ static void VSU_Update(vsu_state* chip, UINT32 clocks, DEV_SMPL* outleft, DEV_SM

if(ch == 4)
{
// Calculate sweep early
INT32 delta = chip->EffFreq[ch] >> (chip->SweepControl & 0x7);
INT32 NewSweepFreq = chip->EffFreq[ch] + ((chip->SweepControl & 0x8) ? delta : -delta);

if(!(chip->EnvControl[ch] & 0x1000))
{
if(NewSweepFreq < 0)
NewSweepFreq = 0;
else if(NewSweepFreq > 0x7FF)
chip->IntlControl[ch] &= ~0x80;
}

chip->SweepModClockDivider--;
while(chip->SweepModClockDivider <= 0)
{
Expand All @@ -487,41 +545,27 @@ static void VSU_Update(vsu_state* chip, UINT32 clocks, DEV_SMPL* outleft, DEV_SM

if(chip->EnvControl[ch] & 0x1000) // Modulation
{
if(chip->ModWavePos < 32 || (chip->EnvControl[ch] & 0x2000))
{
chip->ModWavePos &= 0x1F;

chip->EffFreq[ch] = (chip->EffFreq[ch] + (INT8)chip->ModData[chip->ModWavePos]);
if(chip->EffFreq[ch] < 0)
{
//puts("Underflow");
chip->EffFreq[ch] = 0;
}
else if(chip->EffFreq[ch] > 0x7FF)
{
//puts("Overflow");
chip->EffFreq[ch] = 0x7FF;
}
chip->ModWavePos++;
}
//puts("Mod");
if(chip->ModState == 0 || (chip->EnvControl[ch] & 0x2000))
chip->EffFreq[ch] = (chip->Frequency[ch] + (INT8)chip->ModData[chip->ModWavePos]) & 0x7FF;
if(chip->ModState == 1)
chip->ModState = 2;

// Hardware bug: writing to S5FQ* locks the relevant byte when modulating
if(chip->ModLock == 1)
chip->EffFreq[ch] = (chip->EffFreq[ch] & 0x700) | (chip->Frequency[ch] & 0xFF);
else if(chip->ModLock == 2)
chip->EffFreq[ch] = (chip->EffFreq[ch] & 0xFF) | (chip->Frequency[ch] & 0x700);
}
else // Sweep
else if(chip->ModState < 2) // Sweep
{
chip->EffFreq[ch] = NewSweepFreq;
}

if(++chip->ModWavePos >= 32)
{
INT32 delta = chip->EffFreq[ch] >> (chip->SweepControl & 0x7);
INT32 NewFreq = chip->EffFreq[ch] + ((chip->SweepControl & 0x8) ? delta : -delta);

//printf("Sweep(%d): Old: %d, New: %d\n", ch, EffFreq[ch], NewFreq);

if(NewFreq < 0)
chip->EffFreq[ch] = 0;
else if(NewFreq > 0x7FF)
{
//chip->EffFreq[ch] = 0x7FF;
chip->IntlControl[ch] &= ~0x80;
}
else
chip->EffFreq[ch] = NewFreq;
if(chip->ModState == 0)
chip->ModState = 1;
chip->ModWavePos = 0;
}
}
}
Expand Down
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