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DMA: leave MADR after the transferred data #419

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DMA: leave MADR after the transferred data #419

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13 changes: 13 additions & 0 deletions ps2xRuntime/src/lib/ps2_memory.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1336,6 +1336,9 @@ bool PS2Memory::writeIORegister(uint32_t address, uint32_t value)
if (mode == 0 && qwc > 0)
{
enqueueTransfer(madr, qwc);
// The transfer completes at once here: MADR ends after the data (QWC is
// cleared on completion), as the DMAC leaves it.
m_ioRegisters[channelBase + 0x10] = (madr + qwc * 16u) & 0x7FFFFFF0u;
}
else if (mode == 1)
{
Expand Down Expand Up @@ -1404,6 +1407,9 @@ bool PS2Memory::writeIORegister(uint32_t address, uint32_t value)

int tagsProcessed = 0;
uint32_t lastTagUpper = (chcr >> 16) & 0xFFFFu;
// MADR as the DMAC leaves it: the end of the last tag's payload (PCSX2 hwDmacSrcChain).
uint32_t endMadr = 0u;
bool endMadrValid = false;

while (tagsProcessed < kMaxChainTags)
{
Expand Down Expand Up @@ -1512,6 +1518,11 @@ bool PS2Memory::writeIORegister(uint32_t address, uint32_t value)

if (transferTagData)
appendVifTagData(currentTagAddr);
if (id <= 7u)
{
endMadr = (dataAddr + static_cast<uint32_t>(tagQwc) * 16u) & 0x7FFFFFF0u;
endMadrValid = true;
}

if (hasPayload)
appendData(dataAddr, tagQwc);
Expand All @@ -1522,6 +1533,8 @@ bool PS2Memory::writeIORegister(uint32_t address, uint32_t value)
}

m_ioRegisters[channelBase + 0x30] = tagAddr;
if (endMadrValid)
m_ioRegisters[channelBase + 0x10] = endMadr;
m_ioRegisters[channelBase + 0x40] = asr0;
m_ioRegisters[channelBase + 0x50] = asr1;
chcr = (chcr & ~(0x3u << 4)) | ((asp & 0x3u) << 4);
Expand Down
32 changes: 32 additions & 0 deletions ps2xTest/src/ps2_memory_tests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1100,6 +1100,38 @@ void register_ps2_memory_tests()
t.IsTrue(contentOk, "scratchpad GIF DMA packet bytes should match scratchpad source");
});

tc.Run("GIF DMA leaves MADR after the transferred data, as the DMAC does", [](TestCase &t)
{
// PCSX2 (Gif.cpp, Dmac.cpp hwDmacSrcChain): normal mode advances MADR by QWC*16;
// chain mode sets MADR to each tag's data address and advances it over the payload,
// so at the END tag it points past the last payload. QWC ends at 0.
PS2Memory mem;
t.IsTrue(mem.initialize(), "PS2Memory initialize should succeed");
constexpr uint32_t kGifCh = 0x1000A000u;
uint8_t *rdram = mem.getRDRAM();
mem.setGifPacketCallback([](const uint8_t *, uint32_t) {});

// Normal mode: 2 qwords of zeroed (empty) GIFtags at 0x100000.
std::memset(rdram + 0x100000u, 0, 32u);
t.IsTrue(mem.writeIORegister(kGifCh + 0x10u, 0x100000u), "write MADR");
t.IsTrue(mem.writeIORegister(kGifCh + 0x20u, 2u), "write QWC");
t.IsTrue(mem.writeIORegister(kGifCh + 0x00u, 0x100u), "write CHCR STR (normal)");
mem.processPendingTransfers();
t.Equals(mem.readIORegister(kGifCh + 0x10u), 0x100020u, "normal mode: MADR = start + QWC*16");
t.Equals(mem.readIORegister(kGifCh + 0x20u), 0u, "normal mode: QWC = 0");

// Chain: CNT (1 qword) at 0x110000, REF (2 qwords at 0x120000), END (1 qword).
writeDmaTag(rdram, 0x110000u, makeDmaTag(1u, 1u, 0u, false)); // CNT
writeDmaTag(rdram, 0x110020u, makeDmaTag(2u, 3u, 0x120000u, false)); // REF
writeDmaTag(rdram, 0x110030u, makeDmaTag(1u, 7u, 0u, false)); // END
std::memset(rdram + 0x120000u, 0, 32u);
t.IsTrue(mem.writeIORegister(kGifCh + 0x30u, 0x110000u), "write TADR");
t.IsTrue(mem.writeIORegister(kGifCh + 0x00u, 0x104u), "write CHCR STR|CHAIN");
mem.processPendingTransfers();
t.Equals(mem.readIORegister(kGifCh + 0x10u), 0x110050u, "chain: MADR ends after the END tag's payload");
t.Equals(mem.readIORegister(kGifCh + 0x20u), 0u, "chain: QWC = 0");
});

tc.Run("GIF DMA chain can source tags and payload from 0xF000 scratchpad alias", [](TestCase &t)
{
PS2Memory mem;
Expand Down