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PCE: tweak VDC register commit logic

This commit is contained in:
beirich 2015-05-04 04:54:39 +00:00
parent 69146e5c1b
commit 64741e8973
1 changed files with 23 additions and 17 deletions
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14
BizHawk.Emulation.Cores/Consoles/PC Engine/VDC.cs
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@ -123,23 +123,27 @@ namespace BizHawk.Emulation.Cores.PCEngine
if (RegisterLatch == BYR)
BackgroundY = Registers[BYR] & 0x1FF;
RegisterCommit(RegisterLatch, msbComplete: false);
}
else if (port == MSB)
{
Registers[RegisterLatch] &= 0x00FF;
Registers[RegisterLatch] |= (ushort)(value << 8);
CompleteMSBWrite(RegisterLatch);
RegisterCommit(RegisterLatch, msbComplete: true);
}
}
void CompleteMSBWrite(int register)
void RegisterCommit(int register, bool msbComplete)
{
switch (register)
{
case MARR: // Memory Address Read Register
if (!msbComplete) break;
ReadBuffer = VRAM[Registers[MARR] & 0x7FFF];
break;
case VWR: // VRAM Write Register
if (!msbComplete) break;
if (Registers[MAWR] < VramSize) // Several games attempt to write past the end of VRAM
{
VRAM[Registers[MAWR]] = Registers[VWR];
@ -172,9 +176,11 @@ namespace BizHawk.Emulation.Cores.PCEngine
FrameBuffer = new int[FramePitch * FrameHeight];
break;
case LENR: // Initiate DMA transfer
if (!msbComplete) break;
DmaRequested = true;
break;
case SATB:
if (!msbComplete) break;
SatDmaRequested = true;
break;
}
@ -328,8 +334,8 @@ namespace BizHawk.Emulation.Cores.PCEngine
UpdateSpriteData(i);
}
CompleteMSBWrite(HDR);
CompleteMSBWrite(VDW);
RegisterCommit(HDR, true);
RegisterCommit(VDW, true);
}
}
}