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PPU: Fixes for $2004 register (OAM Read/Write) - Fixes oam_read test, improves oam_stress, and fixes most Micro Machines glitches

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This commit is contained in:
Souryo 2015-12-29 13:23:38 -05:00
parent e41ca6b674
commit 76e060907d
2 changed files with 75 additions and 55 deletions
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126
Core/PPU.cpp
View file

@ -82,7 +82,18 @@ uint8_t PPU::ReadRAM(uint16_t addr)
UpdateStatusFlag();
return _state.Status;
case PPURegisters::SpriteData:
return _spriteRAM[_state.SpriteRamAddr];
if(_scanline <= 240 && IsRenderingEnabled() && (_cycle >= 257 || _cycle <= 64)) {
if(_cycle >= 257 && _cycle <= 320) {
//Set OAM copy buffer to its proper value. This is done here for performance.
//It's faster to only do this here when it's needed, rather than splitting LoadSpriteTileInfo() into an 8-step process
uint8_t step = ((_cycle - 257) % 8) > 3 ? 3 : ((_cycle - 257) % 8);
_secondaryOAMAddr = (_cycle - 257) / 8 * 4 + step;
_oamCopybuffer = _secondarySpriteRAM[_secondaryOAMAddr];
}
return _oamCopybuffer;
} else {
return _spriteRAM[_state.SpriteRamAddr];
}
case PPURegisters::VideoMemoryData:
returnValue = _memoryReadBuffer;
_memoryReadBuffer = _memoryManager->ReadVRAM(_state.VideoRamAddr, MemoryOperationType::Read);
@ -119,6 +130,10 @@ void PPU::WriteRAM(uint16_t addr, uint8_t value)
_spriteDmaCounter--;
} else {
if(_scanline >= 240 || !IsRenderingEnabled()) {
if((_state.SpriteRamAddr & 0x03) == 0x02) {
//"The three unimplemented bits of each sprite's byte 2 do not exist in the PPU and always read back as 0 on PPU revisions that allow reading PPU OAM through OAMDATA ($2004)"
value &= 0xE3;
}
_spriteRAM[_state.SpriteRamAddr] = value;
_state.SpriteRamAddr = (_state.SpriteRamAddr + 1) & 0xFF;
} else {
@ -329,56 +344,56 @@ void PPU::LoadTileInfo()
}
}
void PPU::LoadSpriteTileInfo(uint8_t spriteIndex)
void PPU::LoadSpriteTileInfo()
{
if(IsRenderingEnabled()) {
uint32_t spriteAddr = spriteIndex * 4;
uint8_t spriteY = _secondarySpriteRAM[spriteAddr];
uint8_t tileIndex = _secondarySpriteRAM[spriteAddr + 1];
uint8_t attributes = _secondarySpriteRAM[spriteAddr + 2];
uint8_t spriteX = _secondarySpriteRAM[spriteAddr + 3];
bool backgroundPriority = (attributes & 0x20) == 0x20;
bool horizontalMirror = (attributes & 0x40) == 0x40;
bool verticalMirror = (attributes & 0x80) == 0x80;
uint32_t spriteAddr = _spriteIndex * 4;
uint8_t spriteY = _secondarySpriteRAM[spriteAddr];
uint8_t tileIndex = _secondarySpriteRAM[spriteAddr + 1];
uint8_t attributes = _secondarySpriteRAM[spriteAddr + 2];
uint8_t spriteX = _secondarySpriteRAM[spriteAddr + 3];
bool backgroundPriority = (attributes & 0x20) == 0x20;
bool horizontalMirror = (attributes & 0x40) == 0x40;
bool verticalMirror = (attributes & 0x80) == 0x80;
uint16_t tileAddr;
uint8_t lineOffset;
if(verticalMirror) {
lineOffset = (_flags.LargeSprites ? 15 : 7) - (_scanline - spriteY);
} else {
lineOffset = _scanline - spriteY;
}
uint16_t tileAddr;
uint8_t lineOffset;
if(verticalMirror) {
lineOffset = (_flags.LargeSprites ? 15 : 7) - (_scanline - spriteY);
} else {
lineOffset = _scanline - spriteY;
}
if(_flags.LargeSprites) {
tileAddr = (((tileIndex & 0x01) ? 0x1000 : 0x0000) | ((tileIndex & ~0x01) << 4)) + (lineOffset >= 8 ? lineOffset + 8 : lineOffset);
} else {
tileAddr = ((tileIndex << 4) | _flags.SpritePatternAddr) + lineOffset;
}
if(_spriteIndex < _spriteCount && spriteY < 240) {
_spriteTiles[_spriteIndex].BackgroundPriority = backgroundPriority;
_spriteTiles[_spriteIndex].HorizontalMirror = horizontalMirror;
_spriteTiles[_spriteIndex].VerticalMirror = verticalMirror;
_spriteTiles[_spriteIndex].PaletteOffset = ((attributes & 0x03) << 2) | 0x10;
_spriteTiles[_spriteIndex].LowByte = _memoryManager->ReadVRAM(tileAddr);
_spriteTiles[_spriteIndex].HighByte = _memoryManager->ReadVRAM(tileAddr + 8);
_spriteTiles[_spriteIndex].TileAddr = tileAddr;
_spriteTiles[_spriteIndex].OffsetY = lineOffset;
_spriteTiles[_spriteIndex].SpriteX = spriteX;
} else {
//Fetches to sprite 0xFF for remaining sprites/hidden - used by MMC3 IRQ counter
lineOffset = 0;
tileIndex = 0xFF;
if(_flags.LargeSprites) {
tileAddr = (((tileIndex & 0x01) ? 0x1000 : 0x0000) | ((tileIndex & ~0x01) << 4)) + (lineOffset >= 8 ? lineOffset + 8 : lineOffset);
} else {
tileAddr = ((tileIndex << 4) | _flags.SpritePatternAddr) + lineOffset;
}
if(spriteIndex < _spriteCount && spriteY < 240) {
_spriteTiles[spriteIndex].BackgroundPriority = backgroundPriority;
_spriteTiles[spriteIndex].HorizontalMirror = horizontalMirror;
_spriteTiles[spriteIndex].VerticalMirror = verticalMirror;
_spriteTiles[spriteIndex].PaletteOffset = ((attributes & 0x03) << 2) | 0x10;
_spriteTiles[spriteIndex].LowByte = _memoryManager->ReadVRAM(tileAddr);
_spriteTiles[spriteIndex].HighByte = _memoryManager->ReadVRAM(tileAddr + 8);
_spriteTiles[spriteIndex].TileAddr = tileAddr;
_spriteTiles[spriteIndex].OffsetY = lineOffset;
_spriteTiles[spriteIndex].SpriteX = spriteX;
} else {
//Fetches to sprite 0xFF for remaining sprites/hidden - used by MMC3 IRQ counter
lineOffset = 0;
tileIndex = 0xFF;
if(_flags.LargeSprites) {
tileAddr = (((tileIndex & 0x01) ? 0x1000 : 0x0000) | ((tileIndex & ~0x01) << 4)) + (lineOffset >= 8 ? lineOffset + 8 : lineOffset);
} else {
tileAddr = ((tileIndex << 4) | _flags.SpritePatternAddr) + lineOffset;
}
_memoryManager->ReadVRAM(tileAddr);
_memoryManager->ReadVRAM(tileAddr + 8);
}
_memoryManager->ReadVRAM(tileAddr);
_memoryManager->ReadVRAM(tileAddr + 8);
}
_spriteIndex++;
}
void PPU::LoadNextTile()
@ -481,8 +496,19 @@ void PPU::ProcessPreVBlankScanline()
}
if(_cycle >= 257 && _cycle <= 320) {
//"OAMADDR is set to 0 during each of ticks 257-320 (the sprite tile loading interval) of the pre-render and visible scanlines."
_state.SpriteRamAddr = 0;
if(IsRenderingEnabled()) {
//"OAMADDR is set to 0 during each of ticks 257-320 (the sprite tile loading interval) of the pre-render and visible scanlines." (When rendering)
_state.SpriteRamAddr = 0;
if((_cycle - 261) % 8 == 0) {
//Cycle 261, 269, etc. This is an approximation (each tile is actually loaded in 8 steps (e.g from 257 to 264))
LoadSpriteTileInfo();
} else if(_cycle == 257) {
_spriteIndex = 0;
}
}
} else if(_cycle == 321 && IsRenderingEnabled()) {
_oamCopybuffer = _secondarySpriteRAM[0];
}
}
@ -519,12 +545,6 @@ void PPU::ProcessPrerenderScanline()
InitializeShiftRegisters();
}
}
if(_cycle >= 261 && ((_cycle - 261) & 0x07) == 0 && _cycle <= 320) {
//Unused sprite tile fetches, but vital for MMC3 IRQ counter
uint32_t spriteIndex = (_cycle - 261) / 8;
LoadSpriteTileInfo(spriteIndex);
}
}
void PPU::ProcessVisibleScanline()
@ -544,10 +564,6 @@ void PPU::ProcessVisibleScanline()
if(IsRenderingEnabled()) {
CopyOAMData();
}
} else if(((_cycle - 261) & 0x07) == 0 && _cycle <= 320) {
//Cycle 261, 269, etc.
uint32_t spriteIndex = (_cycle - 261) / 8;
LoadSpriteTileInfo(spriteIndex);
} else if(_cycle == 321 || _cycle == 329) {
LoadTileInfo();
if(_cycle == 329) {
@ -562,7 +578,8 @@ void PPU::CopyOAMData()
{
if(_cycle < 65) {
//Clear secondary OAM at between cycle 0 and 64
_secondarySpriteRAM[_cycle >> 1] = 0xFF;
_oamCopybuffer = 0xFF;
_secondarySpriteRAM[_cycle >> 1] = _oamCopybuffer;
} else {
if(_cycle == 65) {
_overflowCounter = 0;
@ -754,6 +771,7 @@ void PPU::StreamState(bool saving)
Stream<bool>(_spriteTiles[i].HorizontalMirror);
Stream<bool>(_spriteTiles[i].BackgroundPriority);
}
Stream<uint32_t>(_spriteIndex);
Stream<uint32_t>(_spriteCount);
Stream<uint32_t>(_secondaryOAMAddr);
Stream<bool>(_sprite0Visible);

4
Core/PPU.h
View file

@ -130,6 +130,8 @@ class PPU : public IMemoryHandler, public Snapshotable
uint32_t _secondaryOAMAddr = 0;
bool _sprite0Visible = false;
uint32_t _spriteIndex = 0;
uint16_t _spriteDmaCounter = 0;
uint16_t _spriteDmaAddr = 0;
@ -166,7 +168,7 @@ class PPU : public IMemoryHandler, public Snapshotable
void WritePaletteRAM(uint16_t addr, uint8_t value);
void LoadTileInfo();
void LoadSpriteTileInfo(uint8_t spriteIndex);
void LoadSpriteTileInfo();
void ShiftTileRegisters();
void InitializeShiftRegisters();
void LoadNextTile();