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-rw-r--r--contrib/murmurhash3/murmurhash3.c77
1 files changed, 77 insertions, 0 deletions
diff --git a/contrib/murmurhash3/murmurhash3.c b/contrib/murmurhash3/murmurhash3.c
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+++ b/contrib/murmurhash3/murmurhash3.c
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+/* 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
+
+ int i;
+ for(i = -nblocks; i; i++)
+ {
+ uint32_t k1;
+ memcpy(&k1, data + nblocks * 4 + 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;
+}