1 files changed, 76 insertions, 0 deletions
diff --git a/contrib/murmurhash3/murmurhash3.c b/contrib/murmurhash3/murmurhash3.c
new file mode 100644
index 0000000..373c6ce
--- /dev/null
+++ b/contrib/murmurhash3/murmurhash3.c
@@ -0,0 +1,76 @@
+/* This is MurmurHash3. The original C++ code was placed in the public domain
+ * by its author, Austin Appleby.
+ *
+ * SPDX-License-Identifier: CC0-1.0
+ * Source: https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp */
+
+#include "murmurhash3.h"
+#include "string.h"
+
+static inline uint32_t fmix(uint32_t h)
+{
+    h ^= h >> 16;
+    h *= 0x85ebca6b;
+    h ^= h >> 13;
+    h *= 0xc2b2ae35;
+    h ^= h >> 16;
+
+    return h;
+}
+
+static inline uint32_t rotl32(uint32_t x, int8_t r)
+{
+    return (x << r) | (x >> (32 - r));
+}
+
+uint32_t hash(const char* data, size_t len_)
+{
+    const int len = (int) len_;
+    const int nblocks = len / 4;
+
+    uint32_t h1 = 0xc062fb4a;
+
+    uint32_t c1 = 0xcc9e2d51;
+    uint32_t c2 = 0x1b873593;
+
+    //----------
+    // body
+
+    for(int i = 0; i < nblocks; ++i)
+    {
+        uint32_t k1;
+        memcpy(&k1, data + i * sizeof(k1), sizeof(k1));
+
+        k1 *= c1;
+        k1 = rotl32(k1, 15);
+        k1 *= c2;
+
+        h1 ^= k1;
+        h1 = rotl32(h1, 13);
+        h1 = h1*5+0xe6546b64;
+    }
+
+    //----------
+    // tail
+
+    const uint8_t * tail = (const uint8_t*)(data + nblocks*4);
+
+    uint32_t k1 = 0;
+
+    switch(len & 3)
+    {
+        case 3: k1 ^= tail[2] << 16;
+        case 2: k1 ^= tail[1] << 8;
+        case 1: k1 ^= tail[0];
+              k1 *= c1; k1 = rotl32(k1,15); k1 *= c2; h1 ^= k1;
+    }
+
+    //----------
+    // finalization
+
+    h1 ^= len;
+
+    h1 = fmix(h1);
+
+    return h1;
+}