Hey, long time no see!

Correct me if I'm wrong on this, but in order to use MMX, you just have to enable the FPU, right?

But what about SSE/SSE2?

[????]the mmx is available without any else operation than use the registers. as general operations.[/????]

to use fpu, the need to init the environment is a fact.

Only one "problem" with MMX: after using mmx you mast use command EMMS. Thats all. In other - mmx "is free" ))

Cool, thanks.

MMX is only available on later model Pentium 1s and newer. It is lower precision than SSE, and it overlays the FPU stack. And you have to reset it (EMMS or FEMMS for AMD) if you want to use the FPU later. However, SSE is more annoying (alignment, ugh) to use, needs specific OS support, and not necessarily faster. Be sure to test for MMX or SSE availability before using it.