1 files changed, 56 insertions, 5 deletions
diff --git a/util/range.c b/util/range.c
index 098d9d2dc0..9605ccfcbe 100644
--- a/util/range.c
+++ b/util/range.c
@@ -20,11 +20,7 @@
 #include "qemu/osdep.h"
 #include "qemu/range.h"
 
-/*
- * Return -1 if @a < @b, 1 @a > @b, and 0 if they touch or overlap.
- * Both @a and @b must not be empty.
- */
-static inline int range_compare(Range *a, Range *b)
+int range_compare(Range *a, Range *b)
 {
     assert(!range_is_empty(a) && !range_is_empty(b));
 
@@ -70,3 +66,58 @@ GList *range_list_insert(GList *list, Range *data)
 
     return list;
 }
+
+static inline
+GList *append_new_range(GList *list, uint64_t lob, uint64_t upb)
+{
+    Range *new = g_new0(Range, 1);
+
+    range_set_bounds(new, lob, upb);
+    return g_list_append(list, new);
+}
+
+
+void range_inverse_array(GList *in, GList **rev,
+                         uint64_t low, uint64_t high)
+{
+    Range *r, *rn;
+    GList *l = in, *out = *rev;
+
+    for (l = in; l && range_upb(l->data) < low; l = l->next) {
+        continue;
+    }
+
+    if (!l) {
+        out = append_new_range(out, low, high);
+        goto exit;
+    }
+    r = (Range *)l->data;
+
+    /* first range lob is greater than min, insert a first range */
+    if (range_lob(r) > low) {
+        out = append_new_range(out, low, MIN(range_lob(r) - 1, high));
+    }
+
+    /* insert a range inbetween each original range until we reach high */
+    for (; l->next; l = l->next) {
+        r = (Range *)l->data;
+        rn = (Range *)l->next->data;
+        if (range_lob(r) >= high) {
+            goto exit;
+        }
+        if (range_compare(r, rn)) {
+            out = append_new_range(out, range_upb(r) + 1,
+                                   MIN(range_lob(rn) - 1, high));
+        }
+    }
+
+    /* last range */
+    r = (Range *)l->data;
+
+    /* last range upb is less than max, insert a last range */
+    if (range_upb(r) <  high) {
+        out = append_new_range(out, range_upb(r) + 1, high);
+    }
+exit:
+    *rev = out;
+}