Re: Bidirectional UART design for Ravenscar

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 17-08-26 01:24 , Simon Wright wrote:
> I'm trying to implement a two-way interrupt-driven interface via a UART
> with Ravenscar, and having trouble because there is one interrupt with
> multiple causes; a writer must wait until transmission is possible
> before putting the next character, while a reader must wait until
> there's a character to be read.
>
> This makes it hard to write a PO with a single entry (a Ravenscar
> restriction) that serves both requirements.
>
> It occurs to me that the interrupt handler could release one of two
> suspension objects; if it's Tx_Transfer_Complete, release the SO that
> the writer waits on, if it's Rx_Transfer_Complete release the reader's
> SO.
>
> Does that seem a reasonable approach?

IMO yes.

I suppose that Tx and Rx completion can happen at the same time (in the 
same execution of the interrupt handler), in which case both suspension 
objects should be released.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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