p96 is unbelievably Slow!

[itix]

today i have made sdl benchmarks on my both secondary systems (a4k/060-50/cv64/cgx) and (a4k/060-50/p4/p96) to find out how to avoid bad performance of sdl apps in little endian modi.

Problem is SDL doesnt support LE modes natively on BE machines (when speaking of hicolor mode). You can only render into BE framebuffer in fast ram and SDL has to convert framebuffer to LE when copying buffer to VMEM.

I had this problem on MorphOS when I was trying to get some games run at decent speed. It is sort of design flaw in SDL.

[itix]

@itix: this is understandable, and i do not expect  to remove this problem as this is general sdl issue. it can be worked around not using any le modes, or disabling them from the start.

Disabling LE 16bit modes is not an option because then some games will fail.

btw, morphos uses little endian for gfx? i wouldnt expect that, given cgx privides quite good performance on classic so it must be working in big endian.

AFAIK some gfx cards only support LE so it was chosen as default in CGX 5. I think it is because CGX 5 had to support all Radeon variants unlike those phase5 gfx cards tailored for Amiga.

i am not sure if im right here but i recall cgx had some sort fast support for alpha blits. how was that possible? maybe this is the issue?

In CGX 5 there is WritePixelArrayAlpha() and BltBitMap[RastPort]Alpha(). Depending on underlying hardware they can be GPU and AltiVec accelerated. But alpha blits are not usually problem in SDL. MorphOS 1 didnt have accelerated alpha blits yet nobody noticed it when alpha blit accelerated SDL came available for MorphOS 2 users.