Christoph Bumiller <e0425...@student.tuwien.ac.at> writes: > On 06.06.2013 10:34, Richard Sandiford wrote: >> Michel Dänzer <mic...@daenzer.net> writes: >>> On Die, 2013-06-04 at 10:47 +0100, Richard Sandiford wrote: >>>> (2) it uses PIPE_FORMAT_INT_* names with the lsb first rather than the >>>> mesa-like ones with msb first. (I'm happy to change the names to >>>> something else though.) >>>> >>>> The patch isn't in a submittable state yet. I just thought it was worth >>>> posting because the lsb-first names do make the change look a bit more >>>> obvious/less scary :-) >>> I can see the appeal of that, but I also see some danger in that naming >>> scheme: It'll be easy to miss the difference between the two kinds of >>> formats, e.g. when grepping for B8G8R8A8. That's why I'd prefer making >>> the difference more explicit in the naming scheme. Sticking to LSB >>> first, BGRA8888 might already look a little less scary? :) >> I realise this was probably more a question for Jose, but FWIW: >> I liked the names you originally suggested for their consistency with >> mesa and natural number ordering (as you said). The PIPE_FORMAT_INT_* > > I don't like that _INT_, it could be confused with the SINT/UINT > component type postfix, and it's redundant. The distinction provided by > R8G8B8A8 vs RGBA8888 is already sufficient. Neither do I like REV, I > always have to check what order that actually implies (but then I hardly > ever deal with mesa format names). > > Why not just defined it as RxGyBzAw meaning "left to right = lowest > address to highest address" and RGBAxyzw meaning "left to right = > least/most (so that it matches the non-REV variant) to most/least > significant bit-tuple in a word ? And you can do RG16[_]BG16 if you have > 2 words, or R32_G32_B32_A32 for 4 words, but this ugly speciment is > equivalent to R32G32B32A32 so it won't ever appear to hurt your eyes.
I think you're saying we should do what Michel suggested in the quote above, is that right? I.e. PIPE_FORMAT_BGRA8888_UNORM == blue in lsb, alpha in msb. (As opposed to the mesa equivalent MESA_FORMAT_ARGB8888.) I can certainly do that if that's what you'd prefer. As I say, I was just worried that using the opposite order would cause confusion. E.g. the MT_32BIT_????8888 defines in the gallium i915 driver seem to follow the mesa msb-first ordering. OpenVG does too from what I can tell. The wayland ????8888 formats also seem to follow mesa ordering, as does the GBM stuff. If we want lsb->msb ordering than I thought a more obviously-distinct convention might help. I can see that INT_* might not have been the best choice in that regard though :-) Thanks, Richard _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
