hash: move wang mixing funcs into seperate unit

Makefile.am

@@ -91,6 +91,8 @@ UTIL_FILES   =			\
     hash/sha1.hpp		\
     hash/sha2.cpp		\
     hash/sha2.hpp		\
+    hash/wang.hpp		\
+    hash/wang.ipp		\
     image.cpp			\
     image.hpp			\
     introspection.cpp		\

hash.cpp

@@ -17,33 +17,6 @@
 #include "hash.hpp"
 
 
-uint32_t
-util::wang32 (uint32_t key) {
-  uint32_t c2 = 0x27d4eb2d; // a prime or an odd constant
-  key = (key ^ 61) ^ (key >> 16);
-  key = key + (key << 3);
-  key = key ^ (key >> 4);
-  key = key * c2;
-  key = key ^ (key >> 15);
-  return key;
-}
-
-
-uint64_t
-util::wang64 (uint64_t key) {
-  key = (~key) + (key << 21); // key = (key << 21) - key - 1;
-  key = key ^ (key >> 24);
-  key = (key + (key << 3)) + (key << 8); // key * 265
-  key = key ^ (key >> 14);
-  key = (key + (key << 2)) + (key << 4); // key * 21
-  key = key ^ (key >> 28);
-  key = key + (key << 31);
-
-  return key;
-}
-
-
-
 //   32: 2^ 24 + 2^8 + 0x93
 //   64: 2^ 40 + 2^8 + 0xb3
 //  128: 2^ 88 + 2^8 + 0x3B

hash.hpp

@@ -22,10 +22,6 @@
 
 // All hashes are unsuitable for cryptographic operations nnless noted.
 namespace util {
-    // Fast integer mixing operations by Thomas Wang.
-    uint32_t  wang32 (uint32_t key);
-    uint64_t  wang64 (uint64_t key);
-
     // Fast and general hashing using FNV-1a
     uint32_t fnv1a32 (const void *, size_t);
     uint64_t fnv1a64 (const void *, size_t);

hash/wang.hpp

@@ -0,0 +1,30 @@
+/*
+ * 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 2010-2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __UTIL_HASH_WANG_HPP
+#define __UTIL_HASH_WANG_HPP
+
+#include <cstdint>
+
+namespace util { namespace hash {
+    // Thomas Wang's integer mixing functions, ca 2007
+    constexpr uint32_t wang (uint32_t);
+    constexpr uint64_t wang (uint64_t);
+} }
+
+#include "wang.ipp"
+
+#endif

hash/wang.ipp

@@ -0,0 +1,51 @@
+/*
+ * 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 2010-2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifdef __UTIL_HASH_WANG_IPP
+#error
+#endif
+#define __UTIL_HASH_WANG_IPP
+
+
+//-----------------------------------------------------------------------------
+constexpr uint32_t
+util::hash::wang (uint32_t key) {
+    // a prime or an odd constant
+    constexpr uint32_t c2 = 0x27d4eb2d;
+
+    key = (key ^ 61) ^ (key >> 16);
+    key =  key       + (key <<  3);
+    key =  key       ^ (key >>  4);
+    key =  key       * c2;
+    key =  key       ^ (key >> 15);
+
+    return key;
+}
+
+
+//-----------------------------------------------------------------------------
+constexpr uint64_t
+util::hash::wang (uint64_t key) {
+    key = ~key + (key << 21); // key = (key << 21) - key - 1;
+    key =  key ^ (key >> 24);
+    key = (key + (key <<  3)) + (key << 8); // key * 265
+    key =  key ^ (key >> 14);
+    key = (key + (key <<  2)) + (key << 4); // key * 21
+    key =  key ^ (key >> 28);
+    key =  key + (key << 31);
+
+    return key;
+}

noise/turbulence.ipp

@@ -19,7 +19,7 @@
 #endif
 #define __UTIL_NOISE_TURBULENCE_IPP
 
-#include "../hash.hpp"
+#include "../hash/wang.hpp"
 
 
 namespace util { namespace noise {
@@ -28,7 +28,7 @@ namespace util { namespace noise {
     turbulence<T,D,P>::turbulence (seed_t _seed,
                                    vector<2,T> _scale):
         data (_seed),
-        perturb { wang64 (_seed), wang64 (wang64 (_seed)) },
+        perturb { hash::wang (_seed), hash::wang (hash::wang (_seed)) },
         scale (_scale)
     { ; }