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PPU: Fixed offset mode wrapping behavior

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This commit is contained in:
Sour 2019-06-27 20:20:57 -04:00
parent dafe4a2856
commit f4a31045d6
1 changed files with 4 additions and 2 deletions
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6
Core/Ppu.cpp
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@ -765,7 +765,8 @@ void Ppu::ProcessOffsetMode(uint8_t x, uint16_t realX, uint16_t realY, uint16_t
uint16_t columnOffset = ((((columnIndex - 1) << 3) + (_layerConfig[2].HScroll & ~0x07)) >> 3) & (_layerConfig[2].DoubleWidth ? 0x3F : 0x1F);
uint16_t rowOffset = (_layerConfig[2].VScroll >> 3) & (_layerConfig[2].DoubleHeight ? 0x3F : 0x1F);
uint16_t hOffsetAddr = _layerConfig[2].TilemapAddress + (columnOffset << 1) + (rowOffset << 6);
uint16_t tileOffset = (columnOffset << 1) + (rowOffset << 6);
uint16_t hOffsetAddr = _layerConfig[2].TilemapAddress + tileOffset;
if(_bgMode == 4) {
uint16_t offsetValue = _vram[hOffsetAddr] | (_vram[hOffsetAddr + 1] << 8);
@ -777,7 +778,8 @@ void Ppu::ProcessOffsetMode(uint8_t x, uint16_t realX, uint16_t realY, uint16_t
vScroll = (offsetValue & 0x3FF);
}
} else {
uint16_t vOffsetAddr = hOffsetAddr + 0x40;
//The vertical offset is 0x40 bytes later - but wraps around within the tilemap based on the tilemap size (0x800 or 0x1000 bytes)
uint16_t vOffsetAddr = _layerConfig[2].TilemapAddress + ((tileOffset + 0x40) & (_layerConfig[2].DoubleHeight ? 0xFFF : 0x7FF));
uint16_t hOffsetValue = _vram[hOffsetAddr] | (_vram[hOffsetAddr + 1] << 8);
uint16_t vOffsetValue = _vram[vOffsetAddr] | (_vram[vOffsetAddr + 1] << 8);