+/*
+ * Hash function
+ * Source: http://burtleburtle.net/bob/c/lookup3.c
+ * Originally Public Domain
+ */
+
+#define rot(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
+
+#define mix(a, b, c) \
+do { \
+ a -= c; a ^= rot(c, 4); c += b; \
+ b -= a; b ^= rot(a, 6); a += c; \
+ c -= b; c ^= rot(b, 8); b += a; \
+ a -= c; a ^= rot(c, 16); c += b; \
+ b -= a; b ^= rot(a, 19); a += c; \
+ c -= b; c ^= rot(b, 4); b += a; \
+} while (0)
+
+#define final(a, b, c) \
+{ \
+ c ^= b; c -= rot(b, 14); \
+ a ^= c; a -= rot(c, 11); \
+ b ^= a; b -= rot(a, 25); \
+ c ^= b; c -= rot(b, 16); \
+ a ^= c; a -= rot(c, 4);\
+ b ^= a; b -= rot(a, 14); \
+ c ^= b; c -= rot(b, 24); \
+}
+
+static __attribute__((unused))
+uint32_t hash_u32(
+ const uint32_t *k, /* the key, an array of uint32_t values */
+ size_t length, /* the length of the key, in uint32_ts */
+ uint32_t initval) /* the previous hash, or an arbitrary value */
+{
+ uint32_t a, b, c;
+
+ /* Set up the internal state */
+ a = b = c = 0xdeadbeef + (((uint32_t) length) << 2) + initval;
+
+ /*----------------------------------------- handle most of the key */
+ while (length > 3) {
+ a += k[0];
+ b += k[1];
+ c += k[2];
+ mix(a, b, c);
+ length -= 3;
+ k += 3;
+ }
+
+ /*----------------------------------- handle the last 3 uint32_t's */
+ switch (length) { /* all the case statements fall through */
+ case 3: c += k[2];
+ case 2: b += k[1];
+ case 1: a += k[0];
+ final(a, b, c);
+ case 0: /* case 0: nothing left to add */
+ break;
+ }
+ /*---------------------------------------------- report the result */
+ return c;
+}
+