Murmur3

murmur3.c

@@ -0,0 +1,46 @@
+#include <stdint.h>
+#include <stdio.h>
+
+uint32_t murmur3_32(const uint8_t* key, size_t len, uint32_t seed) {
+    uint32_t h = seed;
+    uint32_t c1 = 0xcc9e2d51;
+    uint32_t c2 = 0x1b873593;
+    uint32_t k;
+    size_t i;
+
+    for (i = 0; i + 4 <= len; i += 4) {
+        k = *(uint32_t*)(key + i);
+        k *= c1;
+        k = (k << 15) | (k >> (32 - 15));
+        k *= c2;
+
+        h ^= k;
+        h = (h << 13) | (h >> (32 - 13));
+        h = h * 5 + 0xe6546b64;
+    }
+
+    // Tail handling
+    k = 0;
+    switch (len & 3) {
+        case 3: k ^= key[i + 2] << 16;
+        case 2: k ^= key[i + 1] << 8;
+        case 1: k ^= key[i + 0];
+                k *= c1; k = (k << 15) | (k >> (32 - 15)); k *= c2; h ^= k;
+    }
+
+    h ^= len;
+    h ^= h >> 16;
+    h *= 0x85ebca6b;
+    h ^= h >> 13;
+    h *= 0xc2b2ae35;
+    h ^= h >> 16;
+
+    return h;
+}
+
+int main() {
+    const char *key = "hello world";
+    uint32_t hash = murmur3_32((const uint8_t *)key, 11, 42); // seed = 42
+    printf("MurmurHash3 of \"%s\" is 0x%X\n", key, hash);
+    return 0;
+}