RE: [rtl] Floating point in "restricted" code

[Stephen D. Cohen]

Victor Et. Al.,

        You recently wrote:

> 1. Saving fp state is _slow_ so  you don't need it in an ISR 
> -- there is no performance loss
>        in having the ISR hand over work to a thread.

        I have been trying to figure out how to do this for some time.
Would you please provide a code fragment or clear explanation of how to have
an ISR cause a thread to become computable?

        I thought it would be correct to simply have the thread sleep until
it gets woken up by the ISR, but I am told that this will cause the thread
to run in the ISR context.  That is, obviously, not what we want.  I want to
get in and out of ISR context just as quickly as possible, but cause another
thread to become computable (a high priority hardware handler responding to
the interrupt, for example).

        Any suggestions?

Confusedly Yours,

Steve

P.S. ->
> 3. Rare workarounds are better than rarely used features.  
> Keeping the API simple is 
>    critical.

        I could not agree more.

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