In article <[EMAIL PROTECTED]>
Ben Williamson <[EMAIL PROTECTED]> wrote:
> > > I'm wondering if you considered this option for Thumb: In the
> > > instruction slot immediately following the SWI, place a 16-bit
> > > comment field. Then have the SWI handler step over it to return
> > > to the instruction slot following the extra comment field.
[...]
> I was just thinking of code density, and symmetry with ARM mode to
> some extent. It results in a total 24-bit comment field, and it
> doesn't need any instructions in the calling code to load a register
> with an immediate value. Then again, maybe SWIs aren't very common if
> they all live inside wrapper functions in libc. I'm wondering how the
> performance would compare when you take into account settting up r12
> or whatever.
Hm, but conditional execution of SWIs isn't possible with this system.
The extra branch would affect both performance and code density.
Cheers,
Richard
--
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|_) /| Richard Atterer
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