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PPU: Implement OAM reading and fixed OAM-related bugs (based on blargg's oam tests)

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This commit is contained in:
Sour 2019-02-19 18:41:59 -05:00
parent b5fe44a037
commit 384a5a2c99
1 changed files with 18 additions and 2 deletions
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20
Core/Ppu.cpp
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@ -70,7 +70,9 @@ void Ppu::Exec()
RenderScanline();
} else if(_scanline == 225) {
//Reset OAM address at the start of vblank?
_internalOamAddress = (_oamRamAddress << 1);
if(!_forcedVblank) {
_internalOamAddress = (_oamRamAddress << 1);
}
_frameCount++;
_console->GetSpc()->ProcessEndFrame();
@ -483,6 +485,17 @@ uint8_t* Ppu::GetSpriteRam()
uint8_t Ppu::Read(uint16_t addr)
{
switch(addr) {
case 0x2138: {
uint8_t value;
if(_internalOamAddress < 512) {
value = _oamRam[_internalOamAddress];
} else {
value = _oamRam[0x200 | (_internalOamAddress & 0x1F)];
}
_internalOamAddress = (_internalOamAddress + 1) & 0x3FF;
return value;
}
case 0x213E:
//TODO open bus on bit 4
return (
@ -536,8 +549,11 @@ void Ppu::Write(uint32_t addr, uint8_t value)
} else {
_oamWriteBuffer = value;
}
} else if(_internalOamAddress >= 512) {
} else {
uint16_t address = 0x200 | (_internalOamAddress & 0x1F);
if((_internalOamAddress & 0x01) == 0) {
_oamWriteBuffer = value;
}
_oamRam[address] = value;
}
_internalOamAddress = (_internalOamAddress + 1) & 0x3FF;