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Change to use internal memory and masking bit to disable the channel.

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@209
This commit is contained in:
Sjoerd van der Berg 2002-08-24 07:53:37 +00:00
parent 2df7210adb
commit 2595739e14
1 changed files with 20 additions and 31 deletions
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51
src/hardware/dma.cpp
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@ -57,7 +57,7 @@ struct DMA_CHANNEL {
Bit32u current_count;
Bit8u page;
bool masked;
HostPt host_address;
PhysPt address;
bool addr_changed;
};
@ -142,73 +142,62 @@ void write_dma_page(Bit32u port,Bit8u val) {
}
}
void DMA_8_Read(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
Bit16u DMA_8_Read(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
DMA_CHANNEL * chan=&dma[0].chan[dmachan];
if (chan->masked) return 0;
if (!count) return 0;
/* DMA always does autoinit should work under normal situations */
if (chan->addr_changed) {
/* Calculate the new starting position for dma read*/
chan->addr_changed=false;
chan->host_address=memory+(chan->page << 16)+chan->base_address;
chan->address=(chan->page << 16)+chan->base_address;
chan->current_count=chan->base_count+1;
chan->current_address=chan->base_address;
DMA_DEBUG("DMA:Transfer from %d size %d",(chan->page << 16)+chan->base_address,chan->current_count);
}
if (!count) return;
if (chan->current_count>=count) {
memcpy(buffer,chan->host_address,count);
chan->host_address+=count;
MEM_BlockRead(chan->address,buffer,count);
chan->address+=count;
chan->current_address+=count;
chan->current_count-=count;
return;
return count;
} else {
/* Copy remaining piece of first buffer */
memcpy(buffer,chan->host_address,chan->current_count);
MEM_BlockRead(chan->address,buffer,chan->current_count);
buffer+=chan->current_count;
count-=(Bit16u)chan->current_count;
/* Autoinit reset the dma channel */
chan->host_address=memory+(chan->page << 16)+chan->base_address;
chan->address=(chan->page << 16)+chan->base_address;
chan->current_count=chan->base_count+1;
chan->current_address=chan->base_address;
/* Copy the rest of the buffer */
memcpy(buffer,chan->host_address,count);
chan->host_address+=count;
MEM_BlockRead(chan->address,buffer,count);
chan->address+=count;
chan->current_address+=count;
chan->current_count-=count;
return;
return count;
}
};
void DMA_8_Write(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
if (dma[0].chan[dmachan].addr_changed) {
/* Calculate the new starting position for dma read*/
dma[0].chan[dmachan].addr_changed=false;
dma[0].chan[dmachan].host_address=memory+(dma[0].chan[dmachan].page << 16)+dma[0].chan[dmachan].base_address;
dma[0].chan[dmachan].current_count=dma[0].chan[dmachan].base_count;
dma[0].chan[dmachan].current_count=dma[0].chan[dmachan].current_count;
}
if (dma[0].chan[dmachan].current_count>=count) {
memcpy(dma[0].chan[dmachan].host_address,buffer,count);
dma[0].chan[dmachan].host_address+=count;
dma[0].chan[dmachan].current_address+=count;
dma[0].chan[dmachan].current_count-=count;
return;
} else {
Bit16u DMA_8_Write(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
}
return;
return 0;
};
void DMA_16_Read(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
Bit16u DMA_16_Read(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
return 0;
}
void DMA_16_Write(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
Bit16u DMA_16_Write(Bit32u dmachan,Bit8u * buffer,Bit16u count) {
return 0;
}