fasthash: add initial implementation

Makefile.am

@@ -52,28 +52,29 @@ UTIL_FILES   =		\
     fourcc.hpp		\
     guid.cpp		\
     guid.hpp		\
+    hash.hpp		\
+    hash.cpp		\
     hash/adler.cpp	\
     hash/adler.hpp	\
     hash/bsdsum.cpp	\
     hash/bsdsum.hpp	\
-    hash.cpp		\
     hash/crc.cpp	\
     hash/crc.hpp	\
+    hash/fasthash.cpp	\
     hash/fletcher.hpp	\
     hash/hmac.cpp	\
     hash/hmac.hpp	\
     hash/hotp.cpp	\
     hash/hotp.hpp	\
-    hash.hpp		\
     hash/md2.cpp	\
     hash/md2.hpp	\
     hash/md4.cpp	\
     hash/md4.hpp	\
     hash/md5.cpp	\
     hash/md5.hpp	\
-    hash/murmur.hpp	\
     hash/murmur/common.cpp	\
     hash/murmur/common.hpp	\
+    hash/murmur.hpp	\
     hash/murmur/murmur1.cpp	\
     hash/murmur/murmur1.hpp	\
     hash/murmur/murmur2.cpp	\
@@ -292,6 +293,7 @@ TEST_BIN = 			\
     test/fixed			\
     test/float			\
     test/hash/murmur		\
+    test/hash/fasthash          \
     test/hmac			\
     test/hotp			\
     test/hton			\

hash/fasthash.cpp

@@ -0,0 +1,70 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "fasthash.hpp"
+
+
+///////////////////////////////////////////////////////////////////////////////
+uint64_t
+util::hash::fasthash::mix (uint64_t v)
+{
+    v ^= v >> 23;
+    v *= 0x2127599bf4325c37;
+    v ^= v >> 47;
+
+    return v;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+uint64_t
+util::hash::fasthash::hash64 (const void *restrict data, size_t len, uint64_t seed)
+{
+    static const uint64_t m = 0x880355f21e6d1965;
+
+    uint64_t result = seed ^ (len * m);
+
+    auto cursor = reinterpret_cast<const uint64_t*> (data);
+    auto last   = cursor + len / sizeof (*cursor);
+    for (; cursor < last; ++cursor) {
+        result ^= mix (*cursor);
+        result *= m;
+    }
+
+    size_t remain = len % sizeof (*cursor);
+    if (remain) {
+        auto tail = reinterpret_cast<const uint8_t*> (cursor);
+        
+        uint64_t accum = 0;
+        for (size_t i = 0; i < remain; ++i)
+            accum ^= uint64_t {tail[i]} << i * 8;
+
+        result ^= mix (accum);
+        result *= m;
+    }
+
+    return mix (result);
+} 
+
+
+//-----------------------------------------------------------------------------
+uint32_t
+util::hash::fasthash::hash32 (const void *restrict data, size_t len, uint32_t seed)
+{
+    uint64_t h = hash64 (data, len, seed);
+    return h - (h >> 32);
+}
+

hash/fasthash.hpp

@@ -0,0 +1,33 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __UTIL_HASH_FASTHASH_HPP
+#define __UTIL_HASH_FASTHASH_HPP
+
+#include <cstddef>
+#include <cstdint>
+
+// Zilong Tan's FastHash, via George Marsaglia's "Xorshift RNGs"
+namespace util { namespace hash { namespace fasthash {
+    uint64_t mix (uint64_t);
+
+    uint32_t hash32 (const void *restrict data, size_t len, uint32_t seed);
+    uint64_t hash64 (const void *restrict data, size_t len, uint64_t seed);
+} } }
+
+#endif
+
+

test/hash/fasthash.cpp

@@ -0,0 +1,39 @@
+#include "hash/fasthash.hpp"
+#include "tap.hpp"
+
+#include <cstring>
+
+int
+main (void)
+{
+    util::TAP::logger tap;
+
+    static const struct {
+        uint32_t seed32;
+        uint32_t hash32;
+        uint64_t seed64;
+        uint64_t hash64;
+        const char *str;
+    } TESTS[] = {
+        { 0x00000000, 0x00000000, 0x0000000000000000, 0x0000000000000000, "" },
+        { 0x00000001, 0xd30ac4de, 0x0000000000000001, 0x2127599bf4321e79, "" },
+        { 0xffffffff, 0xf5c7b4b0, 0xffffffffffffffff, 0x9b4792000001368f, "" },
+        { 0xf5c7b4b0, 0x228128b7, 0x9b4792000001368f, 0x67a642098cc81da6, "a" },
+        { 0x228128b7, 0x8400568d, 0x67a642098cc81da6, 0xc906440e03ce99a8, "abc" },
+        { 0x8400568d, 0x12b4858b, 0x67a642098cc81da6, 0x1a36fbf3d71b0737, "message digest" },
+        { 0x12b4858b, 0x730b822e, 0x1a36fbf3d71b0737, 0x7b48e31e3ac40a0f, "abcdefghijklmnopqrstuvwxyz" },
+    };
+
+    bool success32 = true;
+    bool success64 = true;
+
+    for (const auto &t: TESTS) {
+        success32 = success32 && t.hash32 == util::hash::fasthash::hash32 (t.str, strlen (t.str), t.seed32);
+        success64 = success64 && t.hash64 == util::hash::fasthash::hash64 (t.str, strlen (t.str), t.seed64);
+    }
+
+    tap.expect (success32, "fasthash32");
+    tap.expect (success64, "fasthash64");
+
+    return tap.status ();
+}