[Mesa-dev] [PATCH 2/8] genxml: Generate header genX_bits.h

[Jason Ekstrand]

On Wed, Mar 22, 2017 at 2:02 PM, Chad Versace <chadversary at chromium.org>
wrote:

> On Wed 22 Mar 2017, Jason Ekstrand wrote:
> > Wow... This is an impressive quantity of infastructure just to get the
> > number of bits in a field...
>
> In the initial patch, I hand-wrote macros and functions. And I made
> mistakes. That's when I decided to eliminate the mistakes with
> generation. That's why we have the genxml, after all.
>
> > On Tue, Mar 21, 2017 at 4:02 PM, Chad Versace <chadversary at chromium.org>
> > wrote:
>
>
> > > +    REGEX = re.compile('^#define (?P<token_name>GEN(?P<gen>[0-
> > > 9]+)_(?P<token_basename>\w*Surface(Q?)Pitch)_bits).*$')
> > >
> >
> > Can we please not use XML to generate a header and then use regex to
> parse
> > the header?  Let's just use XML for both.
> >
> > I hate to ask for a rewrite, but you should have seen that coming...
>
> Argh... yes, I knew it was coming. Yes, I knew I shouldn't have. But it
> was SOOOO easy.
>
> Now that I've had time to ponder my sin, I no longer want to maintain
> a giant pile of Python "just to get the number of bits in a field". Let
> me propose an alternative: Keep the Python changes to gen_pack_header.py
> that emits the GEN_*Pitch_bits macros, but hand-write the genX_bits.h
> headers. I think that's good compromise. What do you think?
>

Seems reasonable.  You can even do a #define like so:

#define GENX_BITS_DECLARE_LOOKUP(field) \
   static inline uint32_t \
   field##_bits(const struct gen_device_info *devinfo) \
   { \
      switch (devinfo->gen) {
      case 4: return devinfo->is_g4x ? GEN4_##field##_bits :
GEN45_##field##_bits;
      case 5: return GEN5_##field##_bits;
      case 6: return GEN6_##field##_bits;
      case 7: return devinfo->is_haswell ? GEN75_##field##_bits :
GEN7_##field##_bits;
      case 8: return GEN8_##field##_bits;
      case 9: return GEN9_##field##_bits;
      }
   }

GENX_BITS_DECLARE_LOOKUP(RENDER_SURFACE_STATE_SurfacePitch)

Unfortunately, this won't be able to deal with field renames but I think
the right way to deal with that is to just fix the XML.  Also, I didn't
think you actually could include all of the genX_pack headers at the same
time due to name conflicts.  Is this not true?
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