add isl_qpolynomial_get_constant_val

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>

diff --git a/doc/user.pod b/doc/user.pod
index 07b0480..24735f8 100644 (file)
--- a/doc/user.pod
+++ b/doc/user.pod
@@ -4690,6 +4690,11 @@ will not have any existentially quantified variables, but that
 the dimensions of the sets may be different for different
 invocations of C<fn>.
 
+The constant term of a quasipolynomial can be extracted using
+
+       __isl_give isl_val *isl_qpolynomial_get_constant_val(
+               __isl_keep isl_qpolynomial *qp);
+
 To iterate over all terms in a quasipolynomial,
 use
 

diff --git a/include/isl/polynomial.h b/include/isl/polynomial.h
index d355670..3dc08c4 100644 (file)
--- a/include/isl/polynomial.h
+++ b/include/isl/polynomial.h
@@ -25,6 +25,9 @@ unsigned isl_qpolynomial_dim(__isl_keep isl_qpolynomial *qp,
 int isl_qpolynomial_involves_dims(__isl_keep isl_qpolynomial *qp,
        enum isl_dim_type type, unsigned first, unsigned n);
 
+__isl_give isl_val *isl_qpolynomial_get_constant_val(
+       __isl_keep isl_qpolynomial *qp);
+
 __isl_give isl_qpolynomial *isl_qpolynomial_set_dim_name(
        __isl_take isl_qpolynomial *qp,
        enum isl_dim_type type, unsigned pos, const char *s);

diff --git a/isl_polynomial.c b/isl_polynomial.c
index bb33ed6..4e74e52 100644 (file)
--- a/isl_polynomial.c
+++ b/isl_polynomial.c
@@ -1614,6 +1614,42 @@ int isl_qpolynomial_is_cst(__isl_keep isl_qpolynomial *qp,
        return 1;
 }
 
+/* Return the constant term of "up".
+ */
+static __isl_give isl_val *isl_upoly_get_constant_val(
+       __isl_keep struct isl_upoly *up)
+{
+       struct isl_upoly_cst *cst;
+
+       if (!up)
+               return NULL;
+
+       while (!isl_upoly_is_cst(up)) {
+               struct isl_upoly_rec *rec;
+
+               rec = isl_upoly_as_rec(up);
+               if (!rec)
+                       return NULL;
+               up = rec->p[0];
+       }
+
+       cst = isl_upoly_as_cst(up);
+       if (!cst)
+               return NULL;
+       return isl_val_rat_from_isl_int(cst->up.ctx, cst->n, cst->d);
+}
+
+/* Return the constant term of "qp".
+ */
+__isl_give isl_val *isl_qpolynomial_get_constant_val(
+       __isl_keep isl_qpolynomial *qp)
+{
+       if (!qp)
+               return NULL;
+
+       return isl_upoly_get_constant_val(qp->upoly);
+}
+
 int isl_upoly_is_affine(__isl_keep struct isl_upoly *up)
 {
        int is_cst;