X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/ba773d1d2583d6907c3f28ea0c7fa035524cae87..3f8469006c8a8486904d2870733afabfb0d968a7:/src/xbt/dynar.c

diff --git a/src/xbt/dynar.c b/src/xbt/dynar.c
index 7e6f0152c6..2b6a2873d7 100644
--- a/src/xbt/dynar.c
+++ b/src/xbt/dynar.c
@@ -720,6 +720,53 @@ XBT_INLINE void xbt_dynar_sort(xbt_dynar_t dynar,
   _dynar_unlock(dynar);
 }
 
+/** @brief Sorts a dynar according to their color assuming elements can have only three colors.
+ * Since there are only three colors, it is linear and much faster than a classical sort.
+ * See for example http://en.wikipedia.org/wiki/Dutch_national_flag_problem
+ *
+ * \param dynar the dynar to sort
+ * \param color the color function of type (int (compar_fn*) (void*) (void*)). The return value of color is assumed to be 0, 1, or 2.
+ *
+ * At the end of the call, elements with color 0 are at the beginning of the dynar, elements with color 2 are at the end and elements with color 1 are in the middle.
+ *
+ * Remark: if the elements stored in the dynar are structures, the color
+ * function has to retrieve the field to sort first.
+ */
+XBT_PUBLIC(void) xbt_dynar_three_way_partition(xbt_dynar_t const dynar,
+                                               int_f_pvoid_t color)
+{
+  _dynar_lock(dynar);
+  unsigned long int i;
+  unsigned long int p = -1;
+  unsigned long int q = dynar->used;
+  const unsigned long elmsize = dynar->elmsize;
+  void *tmp = xbt_malloc(elmsize);
+  void *elm;
+
+  for (i = 0; i < q;) {
+    void *elmi = _xbt_dynar_elm(dynar, i);
+    int colori = color(elmi);
+
+    if (colori == 1) {
+      ++i;
+    } else {
+      if (colori == 0) {
+        elm = _xbt_dynar_elm(dynar, ++p);
+        ++i;
+      } else {                  /* colori == 2 */
+        elm = _xbt_dynar_elm(dynar, --q);
+      }
+      if (elm != elmi) {
+        memcpy(tmp,  elm,  elmsize);
+        memcpy(elm,  elmi, elmsize);
+        memcpy(elmi, tmp,  elmsize);
+      }
+    }
+  }
+  _dynar_unlock(dynar);
+  xbt_free(tmp);
+}
+
 /** @brief Transform a dynar into a NULL terminated array
  *
  * \param dynar the dynar to transform