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PPU: Fixed wrap-around behavior issues when video ram addr goes from 3FFF to $0000 (ended up reading/writing palette ram by mistake)

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This commit is contained in:
Souryo 2016-01-13 00:06:01 -05:00
parent fbecf90a54
commit 1b57dbc2e0
1 changed files with 3 additions and 3 deletions
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6
Core/PPU.cpp
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@ -159,7 +159,7 @@ uint8_t PPU::ReadRAM(uint16_t addr)
returnValue = _memoryReadBuffer;
_memoryReadBuffer = _memoryManager->ReadVRAM(_state.VideoRamAddr, MemoryOperationType::Read);
if(_state.VideoRamAddr >= 0x3F00) {
if((_state.VideoRamAddr & 0x3FFF) >= 0x3F00) {
returnValue = ReadPaletteRAM(_state.VideoRamAddr) | (_openBus & 0xC0);
openBusMask = 0xC0;
} else {
@ -209,7 +209,7 @@ void PPU::WriteRAM(uint16_t addr, uint8_t value)
} else {
//"Writes to OAMDATA during rendering (on the pre-render line and the visible lines 0-239, provided either sprite or background rendering is enabled) do not modify values in OAM,
//but do perform a glitchy increment of OAMADDR, bumping only the high 6 bits"
_state.SpriteRamAddr += 4;
_state.SpriteRamAddr = (_state.SpriteRamAddr + 4) & 0xFF;
}
}
break;
@ -236,7 +236,7 @@ void PPU::WriteRAM(uint16_t addr, uint8_t value)
_state.WriteToggle = !_state.WriteToggle;
break;
case PPURegisters::VideoMemoryData:
if(_state.VideoRamAddr >= 0x3F00) {
if((_state.VideoRamAddr & 0x3FFF) >= 0x3F00) {
WritePaletteRAM(_state.VideoRamAddr, value);
} else {
_memoryManager->WriteVRAM(_state.VideoRamAddr, value);