Add experimental hash2 dir

external/hash2/cmetrohash.h

@@ -0,0 +1,45 @@
+// metrohash.h
+//
+// The MIT License (MIT)
+//
+// Copyright (c) 2015 J. Andrew Rogers
+//
+// Updated Nov. 2015 to use safe unaligned reads and platform neutral
+// hash. This WILL change hashes on big endian platfors. / mikkelfj
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+
+#ifndef CMETROHASH_H
+#define CMETROHASH_H
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
+#include <stdint.h>
+
+void cmetrohash64_1(const uint8_t * key, uint64_t len, uint32_t seed, uint8_t * out);
+void cmetrohash64_2(const uint8_t * key, uint64_t len, uint32_t seed, uint8_t * out);
+
+#if defined (__cplusplus)
+}
+#endif
+
+#endif /* CMETROHASH_H */