add isl_set_indicator_function

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

diff --git a/doc/user.pod b/doc/user.pod
index 5ff512c..d164c1c 100644 (file)
--- a/doc/user.pod
+++ b/doc/user.pod
@@ -2764,6 +2764,13 @@ be created using the following functions.
        __isl_give isl_pw_aff *isl_pw_aff_from_aff(
                __isl_take isl_aff *aff);
 
+A piecewise quasi affine expression that is equal to 1 on a set
+and 0 outside the set can be created using the following function.
+
+       #include <isl/aff.h>
+       __isl_give isl_pw_aff *isl_set_indicator_function(
+               __isl_take isl_set *set);
+
 Quasi affine expressions can be copied and freed using
 
        #include <isl/aff.h>

diff --git a/include/isl/aff.h b/include/isl/aff.h
index c0bc6cf..d1e968f 100644 (file)
--- a/include/isl/aff.h
+++ b/include/isl/aff.h
@@ -112,6 +112,8 @@ __isl_give isl_pw_aff *isl_pw_aff_empty(__isl_take isl_space *dim);
 __isl_give isl_pw_aff *isl_pw_aff_alloc(__isl_take isl_set *set,
        __isl_take isl_aff *aff);
 
+__isl_give isl_pw_aff *isl_set_indicator_function(__isl_take isl_set *set);
+
 const char *isl_pw_aff_get_dim_name(__isl_keep isl_pw_aff *pa,
        enum isl_dim_type type, unsigned pos);
 int isl_pw_aff_has_dim_id(__isl_keep isl_pw_aff *pa,

diff --git a/isl_aff.c b/isl_aff.c
index e39d118..da896fa 100644 (file)
--- a/isl_aff.c
+++ b/isl_aff.c
@@ -2482,6 +2482,24 @@ __isl_give isl_pw_multi_aff *isl_pw_multi_aff_from_set(__isl_take isl_set *set)
        return isl_pw_multi_aff_from_map(set);
 }
 
+/* Return the piecewise affine expression "set ? 1 : 0".
+ */
+__isl_give isl_pw_aff *isl_set_indicator_function(__isl_take isl_set *set)
+{
+       isl_pw_aff *pa;
+       isl_space *space = isl_set_get_space(set);
+       isl_local_space *ls = isl_local_space_from_space(space);
+       isl_aff *zero = isl_aff_zero_on_domain(isl_local_space_copy(ls));
+       isl_aff *one = isl_aff_zero_on_domain(ls);
+
+       one = isl_aff_add_constant_si(one, 1);
+       pa = isl_pw_aff_alloc(isl_set_copy(set), one);
+       set = isl_set_complement(set);
+       pa = isl_pw_aff_add_disjoint(pa, isl_pw_aff_alloc(set, zero));
+
+       return pa;
+}
+
 /* Plug in "subs" for dimension "type", "pos" of "aff".
  *
  * Let i be the dimension to replace and let "subs" be of the form