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NES: Adds MMC5 PCM read mode #104

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Merged
Fiskbit merged 1 commit into from
May 10, 2026
Merged

NES: Adds MMC5 PCM read mode #104

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10 changes: 9 additions & 1 deletion Core/NES/Mappers/Audio/Mmc5Audio.h
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,14 @@ class Mmc5Audio : public BaseExpansionAudio
_pcmOutput = 0;
}

__forceinline bool GetPcmReadMode() { return _pcmReadMode; }
void HandlePcmRead(uint16_t addr, uint8_t value)
{
if((addr & 0xC000) == 0x8000 && value) {
_pcmOutput = value;
}
}

uint8_t ReadRegister(uint16_t addr)
{
switch(addr) {
Expand Down Expand Up @@ -139,7 +147,7 @@ class Mmc5Audio : public BaseExpansionAudio
break;

case 0x5010:
//TODO: Read mode & PCM IRQs are not implemented
//TODO: PCM IRQs
_pcmReadMode = (value & 0x01) == 0x01;
_pcmIrqEnabled = (value & 0x80) == 0x80;
break;
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9 changes: 9 additions & 0 deletions Core/NES/Mappers/Nintendo/MMC5.h
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Original file line number Diff line number Diff line change
Expand Up @@ -441,6 +441,15 @@ class MMC5 : public BaseMapper, public IExtModeMapperDebug
}
}

uint8_t ReadRam(uint16_t addr) override
{
uint8_t value = BaseMapper::ReadRam(addr);
if(_audio->GetPcmReadMode()) {
_audio->HandlePcmRead(addr, value);
}
return value;
}

void WriteRam(uint16_t addr, uint8_t value) override
{
if(addr >= 0x5C00 && addr <= 0x5FFF && _extendedRamMode <= 1 && !_ppuInFrame) {
Expand Down
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