1 files changed, 42 insertions, 0 deletions
diff --git a/src/hash.c b/src/hash.c
new file mode 100644
index 0000000..6a17e09
--- /dev/null
+++ b/src/hash.c
@@ -0,0 +1,42 @@
+// murmur3 originally by Austin Appleby
+// Copyright (c) 2023, Marvin Borner <dev@marvinborner.de>
+// SPDX-License-Identifier: MIT
+
+#include <stdint.h>
+#include <string.h>
+
+#include <hash.h>
+
+static inline uint32_t murmur_32_scramble(uint32_t k)
+{
+	k *= 0xcc9e2d51;
+	k = (k << 15) | (k >> 17);
+	k *= 0x1b873593;
+	return k;
+}
+
+hash_t hash(const uint8_t *key, size_t len, uint32_t seed)
+{
+	uint32_t h = seed;
+	uint32_t k;
+	for (size_t i = len >> 2; i; i--) {
+		memcpy(&k, key, sizeof(uint32_t));
+		key += sizeof(uint32_t);
+		h ^= murmur_32_scramble(k);
+		h = (h << 13) | (h >> 19);
+		h = h * 5 + 0xe6546b64;
+	}
+	k = 0;
+	for (size_t i = len & 3; i; i--) {
+		k <<= 8;
+		k |= key[i - 1];
+	}
+	h ^= murmur_32_scramble(k);
+	h ^= len;
+	h ^= h >> 16;
+	h *= 0x85ebca6b;
+	h ^= h >> 13;
+	h *= 0xc2b2ae35;
+	h ^= h >> 16;
+	return h;
+}