1 files changed, 19 insertions, 0 deletions
diff --git a/src/libdatastruct/avlnode_doublerotate.c b/src/libdatastruct/avlnode_doublerotate.c
new file mode 100644
index 0000000..da1f31b
--- /dev/null
+++ b/src/libdatastruct/avlnode_doublerotate.c
@@ -0,0 +1,19 @@
+/* ISC license. */
+
+#include <skalibs/avlnode.h>
+#include "avlnode-internal.h"
+
+unsigned int avlnode_doublerotate (avlnode_ref s, unsigned int max, unsigned int i, int h)
+{
+  register unsigned int j = s[i].child[!h] ;
+  register unsigned int k = s[j].child[h] ;
+  s[i].child[!h] = s[k].child[h] ;
+  s[j].child[h] = s[k].child[!h] ;
+  s[k].child[!h] = j ;
+  s[k].child[h] = i ;
+  s[h ? i : j].balance = (s[k].balance < 0) ;
+  s[h ? j : i].balance = -(s[k].balance > 0) ;
+  s[k].balance = 0 ;
+  (void)max ;
+  return k ;
+}