function shortmask_todotted () {
declare -a DMASK

let "DMAST[1]=DMASK[2]=DMASK[3]=DMASK[4]=0"

let "HELPVAR1=$1 / 8"
let "HELPVAR2=$1 % 8"

case $HELPVAR1 in
    1)  let "DMASK[1]=255"
        LASTOCT=2
        ;;
    2)  let "DMASK[1]=255"
        let "DMASK[2]=255"
        LASTOCT=3
        ;;
    3)  let "DMASK[1]=255"
        let "DMASK[2]=255"
        let "DMASK[3]=255"
        LASTOCT=4
        ;;
    4)  let "DMASK[1]=255"
        let "DMASK[2]=255"
        let "DMASK[3]=255"
        let "DMASK[4]=255"
        LASTOCT=0
        ;;
esac

case $HELPVAR2 in
    1)  let "DMASK[LASTOCT]=2#10000000"
        ;;
    2)  let "DMASK[LASTOCT]=2#11000000"
        ;;
    3)  let "DMASK[LASTOCT]=2#11100000"
        ;;
    4)  let "DMASK[LASTOCT]=2#11110000"
        ;;
    5)  let "DMASK[LASTOCT]=2#11111000"
        ;;
    6)  let "DMASK[LASTOCT]=2#11111100"
        ;;
    7)  let "DMASK[LASTOCT]=2#11111110"
        ;;
    8)  let "DMASK[LASTOCT]=2#11111111"
        ;;
esac


echo ${DMASK[1]}.${DMASK[2]}.${DMASK[3]}.${DMASK[4]}

}