From e0ef743090038ee02d656cee11debd2246624ba0 Mon Sep 17 00:00:00 2001
From: redpony <redpony@ec762483-ff6d-05da-a07a-a48fb63a330f>
Date: Mon, 18 Oct 2010 23:24:01 +0000
Subject: kenneth's LM preliminary integration

git-svn-id: https://ws10smt.googlecode.com/svn/trunk@681 ec762483-ff6d-05da-a07a-a48fb63a330f
---
 klm/util/murmur_hash.cc | 129 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 klm/util/murmur_hash.cc

(limited to 'klm/util/murmur_hash.cc')

diff --git a/klm/util/murmur_hash.cc b/klm/util/murmur_hash.cc
new file mode 100644
index 00000000..d58a0727
--- /dev/null
+++ b/klm/util/murmur_hash.cc
@@ -0,0 +1,129 @@
+/* Downloaded from http://sites.google.com/site/murmurhash/ which says "All
+ * code is released to the public domain. For business purposes, Murmurhash is
+ * under the MIT license."
+ * This is modified from the original:
+ * ULL tag on 0xc6a4a7935bd1e995 so this will compile on 32-bit.  
+ * length changed to unsigned int.  
+ * placed in namespace util
+ * add MurmurHashNative
+ * default option = 0 for seed
+ */
+
+#include "util/murmur_hash.hh"
+
+namespace util {
+
+//-----------------------------------------------------------------------------
+// MurmurHash2, 64-bit versions, by Austin Appleby
+
+// The same caveats as 32-bit MurmurHash2 apply here - beware of alignment 
+// and endian-ness issues if used across multiple platforms.
+
+// 64-bit hash for 64-bit platforms
+
+uint64_t MurmurHash64A ( const void * key, std::size_t len, unsigned int seed )
+{
+  const uint64_t m = 0xc6a4a7935bd1e995ULL;
+  const int r = 47;
+
+  uint64_t h = seed ^ (len * m);
+
+  const uint64_t * data = (const uint64_t *)key;
+  const uint64_t * end = data + (len/8);
+
+  while(data != end)
+  {
+    uint64_t k = *data++;
+
+    k *= m; 
+    k ^= k >> r; 
+    k *= m; 
+    
+    h ^= k;
+    h *= m; 
+  }
+
+  const unsigned char * data2 = (const unsigned char*)data;
+
+  switch(len & 7)
+  {
+  case 7: h ^= uint64_t(data2[6]) << 48;
+  case 6: h ^= uint64_t(data2[5]) << 40;
+  case 5: h ^= uint64_t(data2[4]) << 32;
+  case 4: h ^= uint64_t(data2[3]) << 24;
+  case 3: h ^= uint64_t(data2[2]) << 16;
+  case 2: h ^= uint64_t(data2[1]) << 8;
+  case 1: h ^= uint64_t(data2[0]);
+          h *= m;
+  };
+ 
+  h ^= h >> r;
+  h *= m;
+  h ^= h >> r;
+
+  return h;
+} 
+
+
+// 64-bit hash for 32-bit platforms
+
+uint64_t MurmurHash64B ( const void * key, std::size_t len, unsigned int seed )
+{
+  const unsigned int m = 0x5bd1e995;
+  const int r = 24;
+
+  unsigned int h1 = seed ^ len;
+  unsigned int h2 = 0;
+
+  const unsigned int * data = (const unsigned int *)key;
+
+  while(len >= 8)
+  {
+    unsigned int k1 = *data++;
+    k1 *= m; k1 ^= k1 >> r; k1 *= m;
+    h1 *= m; h1 ^= k1;
+    len -= 4;
+
+    unsigned int k2 = *data++;
+    k2 *= m; k2 ^= k2 >> r; k2 *= m;
+    h2 *= m; h2 ^= k2;
+    len -= 4;
+  }
+
+  if(len >= 4)
+  {
+    unsigned int k1 = *data++;
+    k1 *= m; k1 ^= k1 >> r; k1 *= m;
+    h1 *= m; h1 ^= k1;
+    len -= 4;
+  }
+
+  switch(len)
+  {
+  case 3: h2 ^= ((unsigned char*)data)[2] << 16;
+  case 2: h2 ^= ((unsigned char*)data)[1] << 8;
+  case 1: h2 ^= ((unsigned char*)data)[0];
+      h2 *= m;
+  };
+
+  h1 ^= h2 >> 18; h1 *= m;
+  h2 ^= h1 >> 22; h2 *= m;
+  h1 ^= h2 >> 17; h1 *= m;
+  h2 ^= h1 >> 19; h2 *= m;
+
+  uint64_t h = h1;
+
+  h = (h << 32) | h2;
+
+  return h;
+}
+
+uint64_t MurmurHashNative(const void * key, std::size_t len, unsigned int seed) {
+  if (sizeof(int) == 4) {
+    return MurmurHash64B(key, len, seed);
+  } else {
+    return MurmurHash64A(key, len, seed);
+  }
+}
+
+} // namespace util
-- 
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