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ncr5390: dma fixes again (nw)

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After reversing myself on this several times before, I hope I've now finally got it right.
* function/bus complete should proceed when the fifo is empty, to allow devices to send less data than indicated in the transfer count
* raise drq when tcounter = 0 (meaning 65536 bytes)
This commit is contained in:
Patrick Mackinlay 2018-07-05 15:53:04 +07:00
parent 790009096b
commit 391f5c9f90
1 changed files with 5 additions and 5 deletions
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10
src/devices/machine/ncr5390.cpp
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@ -510,16 +510,16 @@ void ncr5390_device::step(bool timeout)
break; break;
case INIT_XFR_FUNCTION_COMPLETE: case INIT_XFR_FUNCTION_COMPLETE:
// wait for dma transfer to complete // wait for dma transfer to complete or fifo to drain
if (dma_command && !(status & S_TC0)) if (dma_command && !(status & S_TC0) && fifo_pos)
break; break;
function_complete(); function_complete();
break; break;
case INIT_XFR_BUS_COMPLETE: case INIT_XFR_BUS_COMPLETE:
// wait for dma transfer to complete // wait for dma transfer to complete or fifo to drain
if (dma_command && !(status & S_TC0)) if (dma_command && !(status & S_TC0) && fifo_pos)
break; break;
bus_complete(); bus_complete();
@ -987,7 +987,7 @@ WRITE8_MEMBER(ncr5390_device::clock_w)
void ncr5390_device::dma_set(int dir) void ncr5390_device::dma_set(int dir)
{ {
dma_dir = dir; dma_dir = dir;
if(dma_dir == DMA_OUT && fifo_pos != 16 && tcounter > fifo_pos) if(dma_dir == DMA_OUT && fifo_pos != 16 && ((tcounter > fifo_pos) || !tcounter))
drq_set(); drq_set();
} }