Re: CGEN_BITSET

[Doug Evans <dje at sebabeach dot org>]

Hi.  Thanks.

More than 32 ISAs?  Yikes!

Going forward, we could add a vbitset attribute kind (or some such), or 
we could convert all bitsets to use CGEN_BITSET.  I guess I'm leaning 
toward the latter, but I can imagine situations where one would rather 
just have an unsigned int.

Dave Brolley wrote:
> Hi Doug,
>
> The mep port required an inderminate and configurable number of ISA's 
> to be possible, so we needed something that could represent an 
> unspecified number of bits (more then 32 or 64 possibly) in a mask. 
> The intent was not to treat isa specially. It just turned out to be 
> the first bit mask to require this treatment.
>
> CGEN_BITSET is simply a bit mask represented by character strings as 
> opposed to integers.
>
> Dave
>
> Doug Evans wrote:
> > Treating "isa" specially is a bit of a hack.  What's the story behind 
> > CGEN_BITSET?
> >
> > (define (gen-attr-type attr)
> >  (if (string=? (string-downcase (gen-sym attr)) "isa")
> >      "CGEN_BITSET"
> >      (case (attr-kind attr)
> >        ((boolean) "int")
> >        ((bitset)  "unsigned int")
> >        ((integer) "int")
> >        ((enum)    (string-append "enum " (string-downcase (gen-sym 
> > attr)) "_attr"))
> >        ))
> > )