initial code repo

[stor4nfv.git] / src / ceph / src / include / hash.h

diff --git a/src/ceph/src/include/hash.h b/src/ceph/src/include/hash.h
new file mode 100644 (file)
index 0000000..2ab9544
--- /dev/null
+++ b/src/ceph/src/include/hash.h
@@ -0,0 +1,64 @@
+#ifndef CEPH_HASH_H
+#define CEPH_HASH_H
+
+#include "acconfig.h"
+
+// Robert Jenkins' function for mixing 32-bit values
+// http://burtleburtle.net/bob/hash/evahash.html
+// a, b = random bits, c = input and output
+
+#define hashmix(a,b,c) \
+       a=a-b;  a=a-c;  a=a^(c>>13); \
+       b=b-c;  b=b-a;  b=b^(a<<8);  \
+       c=c-a;  c=c-b;  c=c^(b>>13); \
+       a=a-b;  a=a-c;  a=a^(c>>12); \
+       b=b-c;  b=b-a;  b=b^(a<<16); \
+       c=c-a;  c=c-b;  c=c^(b>>5);  \
+       a=a-b;  a=a-c;  a=a^(c>>3); \
+       b=b-c;  b=b-a;  b=b^(a<<10); \
+       c=c-a;  c=c-b;  c=c^(b>>15);
+
+
+//namespace ceph {
+
+template <class _Key> struct rjhash { };
+
+inline uint64_t rjhash64(uint64_t key) {
+  key = (~key) + (key << 21); // key = (key << 21) - key - 1;
+  key = key ^ (key >> 24);
+  key = (key + (key << 3)) + (key << 8); // key * 265
+  key = key ^ (key >> 14);
+  key = (key + (key << 2)) + (key << 4); // key * 21
+  key = key ^ (key >> 28);
+  key = key + (key << 31);
+  return key;
+}
+
+inline uint32_t rjhash32(uint32_t a) {
+  a = (a+0x7ed55d16) + (a<<12);
+  a = (a^0xc761c23c) ^ (a>>19);
+  a = (a+0x165667b1) + (a<<5);
+  a = (a+0xd3a2646c) ^ (a<<9);
+  a = (a+0xfd7046c5) + (a<<3);
+  a = (a^0xb55a4f09) ^ (a>>16);
+  return a;
+}
+
+
+template<> struct rjhash<uint32_t> {
+  inline size_t operator()(const uint32_t x) const {
+    return rjhash32(x);
+  }
+};
+
+template<> struct rjhash<uint64_t> {
+  inline size_t operator()(const uint64_t x) const {
+    return rjhash64(x);
+  }
+};
+
+//}
+
+
+
+#endif