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proper display FIFO emulation

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StapleButter
2017-06-26 11:02:10 +02:00
parent 155609b6d9
commit 4afac28263
7 changed files with 105 additions and 34 deletions
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14
src/DMA.cpp
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@ -186,20 +186,6 @@ void DMA::Start()
//printf("ARM%d DMA%d %08X %02X %08X->%08X %d bytes %dbit\n", CPU?7:9, Num, Cnt, StartMode, CurSrcAddr, CurDstAddr, RemCount*((Cnt&0x04000000)?4:2), (Cnt&0x04000000)?32:16);
// special path for the display FIFO. another gross hack.
// the display FIFO seems to be more like a circular buffer that holds 16 pixels
// from which the display controller reads. DMA is triggered every 8 pixels to fill it
// as it is being read from. emulating it properly would be resource intensive.
// proper emulation would only matter if something is trying to feed the FIFO manually
// instead of using the DMA. which is probably never happening. the only thing I know of
// that even uses the display FIFO is the aging cart.
if (StartMode == 0x04)
{
GPU::GPU2D_A->FIFODMA(CurSrcAddr);
CurSrcAddr += 256*2;
return;
}
IsGXFIFODMA = (CPU == 0 && (CurSrcAddr>>24) == 0x02 && CurDstAddr == 0x04000400 && DstAddrInc == 0);
// TODO eventually: not stop if we're running code in ITCM