I made this patch few days ago, it's the complete mmx instruction set for the dosbox interpreter.
It still contain bugs, but I quickly lost interest in it so I'm posting it here in case someone would like to play around with it.
The 64-bit memory accesses are just macros with two 32-bit accesses, so not very optimal.
The instructions are for the interpreter; the recompiler can use it too, but it has to fall back to the interpreter core, with additional overhead.
If you make any change to it, please share it with everyone on this forum.
bye!