1 files changed, 78 insertions, 0 deletions
diff --git a/src/core/lib/gpr/murmur_hash.cc b/src/core/lib/gpr/murmur_hash.cc
new file mode 100644
index 0000000000..3f5e04d211
--- /dev/null
+++ b/src/core/lib/gpr/murmur_hash.cc
@@ -0,0 +1,78 @@
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "src/core/lib/gpr/murmur_hash.h"
+
+#include <string.h>
+
+#define ROTL32(x, r) ((x) << (r)) | ((x) >> (32 - (r)))
+
+#define FMIX32(h)    \
+  (h) ^= (h) >> 16;  \
+  (h) *= 0x85ebca6b; \
+  (h) ^= (h) >> 13;  \
+  (h) *= 0xc2b2ae35; \
+  (h) ^= (h) >> 16;
+
+uint32_t gpr_murmur_hash3(const void* key, size_t len, uint32_t seed) {
+  uint32_t h1 = seed;
+  uint32_t k1;
+
+  const uint32_t c1 = 0xcc9e2d51;
+  const uint32_t c2 = 0x1b873593;
+
+  const uint8_t* keyptr = (const uint8_t*)key;
+  const size_t bsize = sizeof(k1);
+  const size_t nblocks = len / bsize;
+
+  /* body */
+  for (size_t i = 0; i < nblocks; i++, keyptr += bsize) {
+    memcpy(&k1, keyptr, bsize);
+
+    k1 *= c1;
+    k1 = ROTL32(k1, 15);
+    k1 *= c2;
+
+    h1 ^= k1;
+    h1 = ROTL32(h1, 13);
+    h1 = h1 * 5 + 0xe6546b64;
+  }
+
+  k1 = 0;
+
+  /* tail */
+  switch (len & 3) {
+    case 3:
+      k1 ^= ((uint32_t)keyptr[2]) << 16;
+    /* fallthrough */
+    case 2:
+      k1 ^= ((uint32_t)keyptr[1]) << 8;
+    /* fallthrough */
+    case 1:
+      k1 ^= keyptr[0];
+      k1 *= c1;
+      k1 = ROTL32(k1, 15);
+      k1 *= c2;
+      h1 ^= k1;
+  };
+
+  /* finalization */
+  h1 ^= (uint32_t)len;
+  FMIX32(h1);
+  return h1;
+}