#pixman — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #pixman, aggregated by home.social.
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I landed some improvements and small optimizations to #pixman's AltiVec code. See https://gitlab.freedesktop.org/pixman/pixman/-/merge_requests/136
It was fun working with a new (to me) instruction set and trying to figure out how to puzzle together the pieces into something that improved the `pix_multiply()` function (which is kind of the core primitive of most fast paths).
I couldn't figure out a way to use the `vec_mradds`/`vmhraddshs` instruction. Maybe you can? (see https://gitlab.freedesktop.org/pixman/pixman/-/merge_requests/136#note_2699795)
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I fixed an issue in pixman's Altivec code the other day -- https://cgit.freedesktop.org/pixman/commit/?id=207626180d0282bb14a50f2e494174f54ac8a6ce
And in the process, I read through the Altivec docs and discovered that there are vector instructions that pack and unpack between a8r8g8b8 and a1r5g5b5 formats (but nothing fo r5g6b5).
Any clues why? Was a1r5g5b5 really common on Mac OS or something? I don't think I've seen a1r5g5b5 used anywhere.