X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=libecoli%2Fecoli_murmurhash.h;fp=libecoli%2Fecoli_murmurhash.h;h=6b76d34242b6b23f620614ca4fa5faf58514ee08;hb=90efcb0b905753a2eac864bc1a869781d7c31919;hp=0000000000000000000000000000000000000000;hpb=dec2d7fa17ae1e8b3d1dec8e396d057757baf4f3;p=protos%2Flibecoli.git

diff --git a/libecoli/ecoli_murmurhash.h b/libecoli/ecoli_murmurhash.h
new file mode 100644
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+++ b/libecoli/ecoli_murmurhash.h
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+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright 2016, Olivier MATZ <zer0@droids-corp.org>
+ */
+
+/**
+ * MurmurHash3 is a hash implementation that was written by Austin Appleby, and
+ * is placed in the public domain. The author hereby disclaims copyright to this
+ * source code.
+ */
+
+#ifndef ECOLI_MURMURHASH_H_
+#define ECOLI_MURMURHASH_H_
+
+#include <stdint.h>
+
+/** Hash rotation */
+static inline uint32_t ec_murmurhash_rotl32(uint32_t x, int8_t r)
+{
+	return (x << r) | (x >> (32 - r));
+}
+
+/** Add 32-bit to the hash */
+static inline uint32_t ec_murmurhash3_add32(uint32_t h, uint32_t data)
+{
+	data *= 0xcc9e2d51;
+	data = ec_murmurhash_rotl32(data, 15);
+	data *= 0x1b873593;
+	h ^= data;
+	return h;
+}
+
+/** Intermediate mix */
+static inline uint32_t ec_murmurhash3_mix32(uint32_t h)
+{
+	h = ec_murmurhash_rotl32(h,13);
+	h = h * 5 +0xe6546b64;
+	return h;
+}
+
+/** Final mix: force all bits of a hash block to avalanche */
+static inline uint32_t ec_murmurhash3_fmix32(uint32_t h)
+{
+	h ^= h >> 16;
+	h *= 0x85ebca6b;
+	h ^= h >> 13;
+	h *= 0xc2b2ae35;
+	h ^= h >> 16;
+
+	return h;
+}
+
+/**
+ * Calculate a 32-bit murmurhash3
+ *
+ * @param key
+ *   The key (the unaligned variable-length array of bytes).
+ * @param len
+ *   The length of the key, counting by bytes.
+ * @param seed
+ *   Can be any 4-byte value initialization value.
+ * @return
+ *   A 32-bit hash.
+ */
+uint32_t ec_murmurhash3(const void *key, int len, uint32_t seed);
+
+#endif /* ECOLI_MURMURHASH_H_ */