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GB: Fix LYC behavior on scanline 0

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This commit is contained in:
Sour 2020-05-31 15:01:49 -04:00
parent 2ccef88375
commit 86bd6c4deb
1 changed files with 11 additions and 8 deletions
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19
Core/GbPpu.cpp
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@ -195,6 +195,8 @@ void GbPpu::ProcessVblankScanline()
if(_state.Scanline == 154) {
_state.Scanline = 0;
_state.Ly = 0;
_state.LyForCompare = 0;
_console->ProcessEvent(EventType::StartFrame);
if(_console->IsDebugging()) {
_currentEventViewerBuffer = _currentEventViewerBuffer == _eventViewerBuffers[0] ? _eventViewerBuffers[1] : _eventViewerBuffers[0];
@ -209,6 +211,13 @@ void GbPpu::ProcessVblankScanline()
void GbPpu::ProcessFirstScanlineAfterPowerOn()
{
if(_drawnPixels == 160) {
//IRQ flag for Hblank is 1 cycle late compared to the mode register
_state.IrqMode = PpuMode::HBlank;
_drawnPixels = 0;
_state.IdleCycles = 448 - _state.Cycle - 1;
}
switch(_state.Cycle) {
case 1:
_state.IrqMode = PpuMode::NoIrq;
@ -250,11 +259,11 @@ void GbPpu::ProcessVisibleScanline()
switch(_state.Cycle) {
case 3:
_state.Ly = _state.Scanline;
_state.LyForCompare = -1;
if(_state.Scanline > 0) {
//On scanlines 1-143, the OAM IRQ fires 1 cycle early
_state.IrqMode = PpuMode::OamEvaluation;
_state.LyForCompare = -1;
} else {
//On scanline 0, hblank gets set for 1 cycle here
_state.Mode = PpuMode::HBlank;
@ -673,9 +682,8 @@ void GbPpu::Write(uint16_t addr, uint8_t value)
_state.Cycle = 0;
_state.Scanline = 0;
_state.Ly = 0;
_state.LyForCompare = -1;
_state.LyForCompare = 0;
_state.Mode = PpuMode::HBlank;
_state.IrqMode = PpuMode::HBlank;
//Send a blank (white) frame
_lastFrameTime = _gameboy->GetCycleCount();
@ -688,13 +696,8 @@ void GbPpu::Write(uint16_t addr, uint8_t value)
} else {
_isFirstFrame = true;
_state.Cycle = -1;
_state.Scanline = 0;
_state.Ly = 0;
_state.LyForCompare = 0;
_state.IdleCycles = 0;
ResetRenderer();
_state.Mode = PpuMode::HBlank;
_state.IrqMode = PpuMode::HBlank;
_state.LyCoincidenceFlag = _state.LyCompare == _state.LyForCompare;
UpdateStatIrq();