From 5737422376a85ae65612129d49cc1cc68c67cea7 Mon Sep 17 00:00:00 2001
From: "hyunghwan.chung" <hyunghwan.chung@c9d47f8d-4fed-4a2f-8cad-691f5fbe3904>
Date: Fri, 1 Mar 2019 09:13:34 +0000
Subject: [PATCH] changed moo_hash_bytes() to use fnv-1 hash

---
 moo/lib/utl.c | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/moo/lib/utl.c b/moo/lib/utl.c
index f518202..f4517b0 100644
--- a/moo/lib/utl.c
+++ b/moo/lib/utl.c
@@ -216,18 +216,45 @@ moo_uint128_t moo_hton128 (moo_uint128_t x)
  *  utobcstr -> ucstr to bcstr
  */
 
+
+#if MOO_SIZEOF_OOW_T == 4
+#	define FNV_MAGIC_INIT (0x811c9dc5)
+#	define FNV_MAGIC_PRIME (0x01000193)
+#elif MOO_SIZEOF_OOW_T == 8
+#	define FNV_MAGIC_INIT (0xCBF29CE484222325)
+#	define FNV_MAGIC_PRIME (0x100000001B3)
+#elif MOO_SIZEOF_OOW_T == 16
+#	define FNV_MAGIC_INIT (0x6C62272E07BB014262B821756295C58D)
+#	define FNV_MAGIC_PRIME (0x1000000000000000000013B)
+#endif
+
 moo_oow_t moo_hash_bytes (const moo_oob_t* ptr, moo_oow_t len)
 {
-	moo_oow_t h = 0;
+	moo_oow_t h;
 	const moo_uint8_t* bp, * be;
 
 	bp = ptr; be = bp + len;
 
 	/* this hash doesn't produce good distribution */
-	/*while (bp < be) h = h * 31 + *bp++; */
+	/* 
+	h = 0
+	while (bp < be) h = h * 31 + *bp++;
+	*/
 
-	/* SDBM hash is know to produce good overall distribution for many different data sets */
+#if defined(FNV_MAGIC_INIT)
+	/* FNV-1 hash */
+	h = FNV_MAGIC_INIT;
+	while (bp < be)
+	{
+		 h ^= (moo_oow_t)(*bp++);
+		 h *= FNV_MAGIC_PRIME;
+	}
+#else
+	/* SDBM hash is known to produce good overall distribution
+	 * for many different data sets */
+	h = 0;
 	while (bp < be) h = (h << 6) + (h << 16) - h + *bp++;
+#endif
 
 	/* constrain the hash value to be representable in a small integer
 	 * for convenience sake */