BIRD library: The story continues.

Complete resource manages and IP address handling.

1 files changed, 32 insertions, 0 deletions

diff --git a/lib/bitops.c b/lib/bitops.c
new file mode 100644
index 0000000..10bca04
--- /dev/null
+++ b/lib/bitops.c
@@ -0,0 +1,32 @@
+/*
+ *	BIRD Library -- Generic Bit Operations
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#include "nest/bird.h"
+#include "bitops.h"
+
+u32
+u32_mkmask(unsigned n)
+{
+  return n ? ~((1 << (32 - n)) - 1) : 0;
+}
+
+int
+u32_masklen(u32 x)
+{
+  int l = 0;
+  u32 n = ~x;
+
+  if (n & (n+1)) return -1;
+  if (x & 0x0000ffff) { x &= 0x0000ffff; l += 16; }
+  if (x & 0x00ff00ff) { x &= 0x00ff00ff; l += 8; }
+  if (x & 0x0f0f0f0f) { x &= 0x0f0f0f0f; l += 4; }
+  if (x & 0x33333333) { x &= 0x33333333; l += 2; }
+  if (x & 0x55555555) l++;
+  if (x & 0xaaaaaaaa) l++;
+  return l;
+}