Hi
i have a quesiton about salc instruction.
i saw it in fasm's docs but i couldn't find it in intel's documentations.
am i blind ?

It's an undocumented instruction

BTW, Intel claims it is undefined and reserved, not that it is kind of NOP.

There is no mention of what it does in the AMD64 Volume 3, but if you search it you will it in the table A-1 marked with number 3 which means "3. Invalid in 64-bit mode.".

I though it was documented and actually I used it in a code recently posted by me. Well, I take resposability only up to the currently made processors to the date

You can use the documented SETcc instruction instead - for instance, SETC AL, which is roughly equivalent to SALC (1 instead of 0xFF though).

If you really need an equivalent then use sbb al, al instead (if changing the flags isn't a problem).

I personally don't see it overly useful (unless you want to stuff FF in AL upon a certain tested condition), but i don't see why companies would put instructions in their processors if they don't plan on supporting it... Unless they're reserving the name for something else... But i don't see the point in reserving this name or it's operation.

TetrOS uses it.