1 files changed, 45 insertions, 0 deletions
diff --git a/util/hash.cc b/util/hash.cc
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index 0000000..ba18180
--- /dev/null
+++ b/util/hash.cc
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+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include <string.h>
+#include "util/coding.h"
+#include "util/hash.h"
+
+namespace leveldb {
+
+uint32_t Hash(const char* data, size_t n, uint32_t seed) {
+  // Similar to murmur hash
+  const uint32_t m = 0xc6a4a793;
+  const uint32_t r = 24;
+  const char* limit = data + n;
+  uint32_t h = seed ^ (n * m);
+
+  // Pick up four bytes at a time
+  while (data + 4 <= limit) {
+    uint32_t w = DecodeFixed32(data);
+    data += 4;
+    h += w;
+    h *= m;
+    h ^= (h >> 16);
+  }
+
+  // Pick up remaining bytes
+  switch (limit - data) {
+    case 3:
+      h += data[2] << 16;
+      // fall through
+    case 2:
+      h += data[1] << 8;
+      // fall through
+    case 1:
+      h += data[0];
+      h *= m;
+      h ^= (h >> r);
+      break;
+  }
+  return h;
+}
+
+
+}  // namespace leveldb