swap function with generic parameters for Int KOTLIN

/*
 *swap function with generic parameters for Int  KOTLIN
 * Antonio Villanueva Segura
 */

fun main() {
    var ushort:UShort=0xABCDU //UShort kotlin.Unit
    var uint:UInt=0x1234U    //UInt kotlin.Unit
    var int:Int=0x5678    //UInt kotlin.Unit
    var short:Int=0x9ABC    //UInt kotlin.Unit
    println ( "%04x".format (swap (ushort.toInt())))
    println ( "%04x".format (swap (uint.toInt())))
    println ( "%04x".format (swap (int.toInt())))
    println ( "%04x".format (swap (short.toInt())))

}

//Swap Fun
fun <T>swap(w:T) :T{
    var H:UShort=0x00U
    var L:UShort=0x00U

    if ( (w is Int) ){ //Test Only Int
        H=( w.toInt().shr(8) ).toUShort()
        L=( w.toInt().shl(8) ).toUShort()
        return ((H or L).toInt() ) as T
    }

        return w //No changed error
}