diff --git a/py_gen/oftype.py b/py_gen/oftype.py
index 51b8e13..3893865 100644
--- a/py_gen/oftype.py
+++ b/py_gen/oftype.py
@@ -116,6 +116,11 @@
         init='0',
         pack='util.pack_checksum_128(%s)',
         unpack="util.unpack_checksum_128(%s)"),
+
+    'of_bitmap_512_t': OFTypeData(
+        init='set()',
+        pack='util.pack_bitmap_512(%s)',
+        unpack="util.unpack_bitmap_512(%s)"),
 }
 
 ## Fixed length strings
diff --git a/py_gen/templates/util.py b/py_gen/templates/util.py
index 85181dc..7558576 100644
--- a/py_gen/templates/util.py
+++ b/py_gen/templates/util.py
@@ -173,6 +173,28 @@
         x >>= 1
     return value
 
+def pack_bitmap_512(value):
+    words = [0] * 8
+    for v in value:
+        assert v < 512
+        words[7-v/64] |= 1 << (v % 64)
+    return struct.pack("!8Q", *words)
+
+def unpack_bitmap_512(reader):
+    words = reader.read("!8Q")
+    x = 0l
+    for word in words:
+        x <<= 64
+        x |= word
+    i = 0
+    value = set()
+    while x != 0:
+        if x & 1 == 1:
+            value.add(i)
+        i += 1
+        x >>= 1
+    return value
+
 def pack_checksum_128(value):
     return struct.pack("!QQ", (value >> 64) & MASK64, value & MASK64)
 
diff --git a/py_gen/tests/of13.py b/py_gen/tests/of13.py
index c5a16b2..c99ee34 100644
--- a/py_gen/tests/of13.py
+++ b/py_gen/tests/of13.py
@@ -126,5 +126,18 @@
             else:
                 fn()
 
+class TestUtils(unittest.TestCase):
+    def check_bitmap_512(self, value, data):
+        self.assertEquals(data, ofp.util.pack_bitmap_512(set(value)))
+        self.assertEquals(ofp.util.unpack_bitmap_512(OFReader(data)), set(value))
+
+    def test_bitmap_512(self):
+        self.check_bitmap_512([0], "\x00" * 63 + "\x01")
+        self.check_bitmap_512([8], "\x00" * 62 + "\x01\x00")
+        self.check_bitmap_512([63], "\x00" * 56 + "\x80" + "\x00" * 7)
+        self.check_bitmap_512([64], "\x00" * 55 + "\x01" + "\x00" * 8)
+        self.check_bitmap_512([511], "\x80" + "\x00" * 63)
+        self.check_bitmap_512([5, 67, 90], "\x00" * 52 + "\x04\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x20")
+
 if __name__ == '__main__':
     unittest.main()