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added ppu read latch

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Lauchmelder 2021-10-30 19:42:17 +02:00
parent 2fdae00ff8
commit 9ab5ac3c13
2 changed files with 5 additions and 2 deletions
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6
NES Emulator/ppu.c
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@ -131,7 +131,8 @@ Byte ppuRead(struct PPU* ppu, Word addr)
{ {
if (ppu->ppuAddress.raw < 0x2000) if (ppu->ppuAddress.raw < 0x2000)
{ {
val = readCartridgePPU(ppu->bus->cartridge, ppu->ppuAddress.raw); val = ppu->ppuReadLatch;
ppu->ppuReadLatch = readCartridgePPU(ppu->bus->cartridge, ppu->ppuAddress.raw);
} }
else if (0x2000 <= ppu->ppuAddress.raw && ppu->ppuAddress.raw < 0x3F00) else if (0x2000 <= ppu->ppuAddress.raw && ppu->ppuAddress.raw < 0x3F00)
{ {
@ -140,7 +141,8 @@ Byte ppuRead(struct PPU* ppu, Word addr)
if (effectiveAddress >= 0x2800) if (effectiveAddress >= 0x2800)
effectiveAddress -= 0x0400; effectiveAddress -= 0x0400;
val = ppu->nameTables[0][(effectiveAddress - 0x2000) & 0x0FFF]; val = ppu->ppuReadLatch;
ppu->ppuReadLatch = ppu->nameTables[0][(effectiveAddress - 0x2000) & 0x0FFF];
} }
else if (0x3F00 <= ppu->ppuAddress.raw && ppu->ppuAddress.raw < 0x4000) else if (0x3F00 <= ppu->ppuAddress.raw && ppu->ppuAddress.raw < 0x4000)
{ {

1
NES Emulator/ppu.h
View file

@ -113,6 +113,7 @@ struct PPU
Word raw; Word raw;
} ppuAddress; } ppuAddress;
Byte ppuAddressWriteTarget; Byte ppuAddressWriteTarget;
Byte ppuReadLatch;
Byte oamdma; Byte oamdma;