I came into another issue.
I have font array in EEPROM, and need to set offset for reading it. Depending on charset, this offset can be negative and positive.

So I have to do it in a way like this:

if langvar[x]=0 then
Y=(topline[x])*8+OFS

if langvar[x]=1 then
Y=(topline[x])*8-OFS

Can these two joined into single operation somehow?