Move SkChecksum::Murmur3 out of the header.

include/private/SkChecksum.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkChecksum_DEFINED
 #define SkChecksum_DEFINED
 
@@ skipping 58 matching lines @@
     /**
      * Calculate 32-bit Murmur hash (murmur3).
      * This should take 2-3x longer than SkChecksum::Compute, but is a considerably better hash.
      * See en.wikipedia.org/wiki/MurmurHash.
      *
      *  @param data Memory address of the data block to be processed.
      *  @param size Size of the data block in bytes.
      *  @param seed Initial hash seed. (optional)
      *  @return hash result
      */
-    static uint32_t Murmur3(const void* data, size_t bytes, uint32_t seed=0) {
-        // Use may_alias to remind the compiler we're intentionally violating strict aliasing,
-        // and so not to apply strict-aliasing-based optimizations.
-        typedef uint32_t SK_ATTRIBUTE(may_alias) aliased_uint32_t;
-        typedef uint8_t SK_ATTRIBUTE(may_alias) aliased_uint8_t;
-
-        // Handle 4 bytes at a time while possible.
-        const aliased_uint32_t* safe_data = (const aliased_uint32_t*)data;
-        const size_t words = bytes/4;
-        uint32_t hash = seed;
-        for (size_t i = 0; i < words; i++) {
-            uint32_t k = safe_data[i];
-            k *= 0xcc9e2d51;
-            k = (k << 15) | (k >> 17);
-            k *= 0x1b873593;
-
-            hash ^= k;
-            hash = (hash << 13) | (hash >> 19);
-            hash *= 5;
-            hash += 0xe6546b64;
-        }
-
-        // Handle last 0-3 bytes.
-        const aliased_uint8_t* safe_tail = (const uint8_t*)(safe_data + words);
-        uint32_t k = 0;
-        switch (bytes & 3) {
-            case 3: k ^= safe_tail[2] << 16;
-            case 2: k ^= safe_tail[1] <<  8;
-            case 1: k ^= safe_tail[0] <<  0;
-                    k *= 0xcc9e2d51;
-                    k = (k << 15) | (k >> 17);
-                    k *= 0x1b873593;
-                    hash ^= k;
-        }
-
-        hash ^= bytes;
-        return Mix(hash);
-    }
+    static uint32_t Murmur3(const void* data, size_t bytes, uint32_t seed=0);
 
     /**
      *  Compute a 32-bit checksum for a given data block
      *
      *  WARNING: this algorithm is tuned for efficiency, not backward/forward
      *  compatibility.  It may change at any time, so a checksum generated with
      *  one version of the Skia code may not match a checksum generated with
      *  a different version of the Skia code.
      *
      *  @param data Memory address of the data block to be processed. Must be
@@ skipping 65 matching lines @@
     SK_WHEN(sizeof(K) != 4, uint32_t) operator()(const K& k) const {
         return SkChecksum::Murmur3(&k, sizeof(K));
     }
 
     uint32_t operator()(const SkString& k) const {
         return SkChecksum::Murmur3(k.c_str(), k.size());
     }
 };
 
 #endif