This is the official home page of the MMX Emulation Library Project for Linux/x86. Here the German mirror. And here the French translation.
It works only on Linux, and on Intel compatible processors, for the moment.
FAQ: MMX-EMU does not work under Windows, and we don't know about any equivalent package for Windows, sorry. Please do not send us mails about this, we won't answer them.
This library provides a simple way to execute (but slowly) binaries that use MMX instructions, on processors that do not support them.
It can be used if you want to develop MMX code, or execute MMX binaries, on a non-MMX Intel compatible CPU. Note that well written MMX binaries should contain the equivalent non-MMX code, since the emulation will always be really slow, and MMX code is all about speed.
The emulator also contains emulation code for Cyrix and AMD variants of MMX (EMMX and 3DNow!).
Source code to download (under GNU's Library General Public License):