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n64: fix PI DMA implementation to handle a newly discovered behavior #1385

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Feb 5, 2024
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n64: fix PI DMA implementation to handle a newly discovered behavior #1385

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50 changes: 25 additions & 25 deletions ares/n64/pi/dma.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10,43 +10,43 @@ auto PI::dmaRead() -> void {

auto PI::dmaWrite() -> void {
u8 mem[128];
bool first_block = true;
i32 length = io.writeLength+1;
i32 maxBlockSize = 128;
bool firstBlock = true;

io.writeLength = 0x7F;
if (length <= 8) io.writeLength -= io.dramAddress&7;
if constexpr(Accuracy::CPU::Recompiler) {
cpu.recompiler.invalidateRange(io.dramAddress, (length + 1) & ~1);
}

while (length > 0) {
u32 dest = io.dramAddress & 0x7FFFFE;
i32 misalign = dest & 7;
i32 block_len = 128 - misalign;
i32 cur_len = min(length, block_len);

length -= cur_len;
if (length.bit(0)) length += 1;
i32 misalign = io.dramAddress & 7;
i32 distEndOfRow = 0x800-(io.dramAddress&0x7ff);
i32 blockLen = min(maxBlockSize-misalign, distEndOfRow);
i32 curLen = min(length, blockLen);

i32 rom_len = (cur_len + 1) & ~1;
for (u32 i = 0; i < rom_len; i += 2) {
for (int i=0; i<curLen; i+=2) {
u16 data = busRead<Half>(io.pbusAddress);
mem[i + 0] = data >> 8;
mem[i + 1] = data & 0xFF;
mem[i+0] = data >> 8;
mem[i+1] = data >> 0;
io.pbusAddress += 2;
length -= 2;
}

if (first_block) {
if (cur_len == block_len-1) cur_len++;
cur_len = max(cur_len-misalign, 0);
if (firstBlock && curLen < 127-misalign) {
for (i32 i = 0; i < curLen-misalign; i++) {
rdram.ram.write<Byte>(io.dramAddress++, mem[i], "PI DMA");
}
} else {
for (i32 i = 0; i < curLen-misalign; i+=2) {
rdram.ram.write<Byte>(io.dramAddress++, mem[i+0], "PI DMA");
rdram.ram.write<Byte>(io.dramAddress++, mem[i+1], "PI DMA");
}
}

if constexpr(Accuracy::CPU::Recompiler) {
cpu.recompiler.invalidateRange(io.dramAddress, cur_len);
}

for (u32 i = 0; i < cur_len; i++)
rdram.ram.write<Byte>(io.dramAddress++, mem[i], "PI DMA");
io.dramAddress = (io.dramAddress + 7) & ~7;

first_block = false;
io.writeLength = curLen <= 8 ? 127-misalign : 127;
firstBlock = false;
maxBlockSize = distEndOfRow < 8 ? 128-misalign : 128;
}
}

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