Re: [Mesa3d-dev] texutil updates

[Brian P. <br...@va...>]

Gareth Hughes wrote:
> 
> I'm in the process of moving the Radeon DRI driver over to Mesa's
> single-copy texture mechanism.  I'm using this opportunity to wrap up my
> changes to texutil.c and friends, which includes full MMX assembly
> optimizations for most of the interesting cases.
> 
> I've noticed that this is special-cased:
> 
>       case MESA_R5_G6_B5:
>          if (srcFormat == GL_RGB && srcType == GL_UNSIGNED_SHORT_5_6_5) {
>             ...
>          }
> 
> However, later we see this:
> 
>       case MESA_A4_R4_G4_B4:
>          /* store as 16-bit texels (GR_TEXFMT_ARGB_4444) */
>          if (srcFormat == GL_BGRA && srcType == GL_UNSIGNED_SHORT_4_4_4_4_REV){
>             ...
>          }
> 
> And this:
> 
>       case MESA_A1_R5_G5_B5:
>          /* store as 16-bit texels (GR_TEXFMT_ARGB_1555) */
>          if (srcFormat == GL_BGRA && srcType == GL_UNSIGNED_SHORT_1_5_5_5_REV){
>              ...
>          }
> 
> In all cases, the data is memcpy'd to the final destination image.  I'm
> going to change the first case to this:
> 
>       case MESA_R5_G6_B5:
>          if (srcFormat == GL_BGR && srcType == GL_UNSIGNED_SHORT_5_6_5_REV) {
>             ...
>          }

Don't remove the original case.

GL_BGR / GL_UNSIGNED_SHORT_5_6_5_REV is equivalent to GL_RGB /
GL_UNSIGNED_SHORT_5_6_5.  In both cases, the component packing
in the GLushort is RRRRRGGGGGGBBBBB.

So, the condition should be:

 if ((srcFormat == GL_RGB && srcType == GL_UNSIGNED_SHORT_5_6_5) ||
     (srcFormat == GL_BGR && srcType == GL_UNSIGNED_SHORT_5_6_5_REV)) {



> to fit with the rest of the cases and to make it actually useful to Mesa
> drivers that use little-endian texture images.  If you don't want this
> to happen, scream now...

-Brian