function do_xsetech(wdm)
// Copyright INRIA
xset('alufunction',3);xbasc();xselect();
xsetech([-1 -1 8 8]/6,[wdm(3),wdm(4),wdm(3)+wdm(5),wdm(4)+wdm(6)])
xset('alufunction',6)
