Hi Maarten,
I'm not sure yet what I want :-)
The problem is that during the dma the on-chip xram does not need any
special threatment, while the off-chip xram does.
I think multibyte variables must be supported. For performance reasons,
it might be better to cluster movx instructions (like __critical {}).
But this might lead to problems,
when the dma engine might not be able to write its data to the xram and
overflow.
best regards
Dani
Maarten Brock wrote:
> Dani,
>
> This totally depends on what you would want the compiler
> to do. Should this appear around every MOVX instruction
> or also around several when dealing with multibyte
> variables? Or even around iCodes (elementary
> instructions for the compiler)? Or bigger yet?
>
> In case the first is good enough this can easily be
> solved with a peephole rule:
>
> replace {
> movx %1,%2
> } by {
> jb _DMA0XBY,.
> setb _DMA0HLT
> movx %1,%2
> clr _DMA0HLT
> }
>
> If necessary you can also insert code to select the
> proper SFR page and return it to previous setting
> afterwards.
>
> Greets,
> Maarten
>
>
>> Dear list,
>>
>> the silabs C8051F060 incorporated a DMA controller. While the DMA
>> controller is running, a special procedure must be followed to access
>> the xram (wait DMA0XBY ==0, set DMA0HLT, access xram, clr DMA0HLT bit).
>> I wonder how much work it would be to teach this feature to SDCC?
>>
>> best regards
>>
>> Dani
>>
>
>
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