[AndySedeyn]

This should do.

pawn Код:

new timeshift = -1;
new shifthour;

forward FixHour(hour);
public FixHour(hour)
{
    hour = timeshift+hour;
    if(hour < 0) { hour = hour+24; }
    else if(hour > 23) { hour = hour-24; }
    shifthour = hour;
    return 1;
}