  For any primitive substitution whose Perron eigenvalue is Pisot unit, we
construct a domain exchange measurably conjugated to the subshift. And we give
a condition for the subshift to be a finite extension of a torus translation.
For the particular case of weakly irreducible Pisot substitution, we show that
the subshift is either a finite extension of a torus translation, either a
power of the subshift is weakly mixing. And we provide an algorithm to compute
eigenvalues of the subshift associated to any primitive pseudo-unimodular
substitution.
