[Mesa-dev] [PATCH 3/6] glsl: move half<->float convertion to util

[Rob Clark]

On Mon, Oct 12, 2015 at 12:47 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
>> > +/**
>> > + * Convert a 2-byte half float to a 4-byte float.
>> > + * Based on code from:
>> > + * http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
>> > + */
>> > +static inline float
>> > +_mesa_half_to_float(GLhalfARB val)
>> > +{
>> > +   return half_to_float(val);
>> > +}
>
> This is kind of ugly. How hard would it really be to just replace the uses
> with the new name?  I don't think its used *that* often.

hmm, ~20-30 call sites.. not impossible to update them all, but I
think it should be a separate patch and then drop the compat shims
rather than one big patch that changes everything..

We could also keep the _mesa_half_to_float() name.. but I really
wanted to drop the GLhalfARB and not drag along GL typedefs.  If no
one objects to just replacing GLhalfARB with uint16_t.

I could go either way.

>> > +
>> > +#include <stdint.h>
>> > +
>> > +#ifdef __cplusplus
>> > +extern "C" {
>> > +#endif
>> > +
>> > +uint16_t float_to_half(float val);
>> > +float half_to_float(uint16_t val);
>>
>> I think these functions need to be prefixed with something -- util_*
>> or something or just leave them as _mesa_*.
>
> Unfortunately, until is kind of a grab-bag right now.  Some stuff has a
> util_ prefix, some has kept its _mesa_ or u_ prefix depending on whether it
> was copied from Mesa or gallium, and some (hash_table for example) isn't
> prefixed at all.  Personally, I'd go with either util_ (it is a utility
> library) or just keep _mesa_ (this is still the mesa project after all). I'm
> not going to be too insistent though

the util_ prefix conflicts w/ u_half.h (which appears to implement
basically the same thing in a simpler way, but maybe not compatible
enough to just switch to the gallium implementation?  Otherwise the
easier approach would be to just move the gallium implementation to
global util directory and use that instead)..  I was going to use
convert_ prefix but that also conflicts..

BR,
-R