Added murmur3 hash (compile time -DMURMUR3) support to hash.cc hash.h

1 files changed, 156 insertions, 2 deletions

diff --git a/vowpalwabbit/hash.cc b/vowpalwabbit/hash.cc
index 429ea187..360137c9 100644
--- a/vowpalwabbit/hash.cc
+++ b/vowpalwabbit/hash.cc
@@ -1,7 +1,8 @@
 // Tweaked for VW and contributed by Ariel Faigon.
 // Original at: http://murmurhash.googlepages.com/
 //
-// Based on MurmurHash2, by Austin Appleby
+// Incorporates MurmurHash2, by Austin Appleby
+// Incorporates MurmurHash3, by Austin Appleby
 //
 // Note - This code makes a few assumptions about how your machine behaves:
 //
@@ -15,9 +16,160 @@
 //  2. It will not produce the same results on little-endian and
 //     big-endian machines.
 //
-#include <stdint.h>	/* defines uint32_t etc */
+
+// Platform-specific functions and macros
+// Microsoft Visual Studio
+#if defined(_MSC_VER)
+    typedef unsigned char uint8_t;
+    typedef unsigned long uint32_t; 
+    typedef unsigned __int64 uint64_t;
+// Other compilers
+#else   // defined(_MSC_VER)
+#  include <stdint.h>	/* defines uint32_t etc */
+#endif // !defined(_MSC_VER)
+
 #include <sys/types.h>	/* defines size_t */
 
+#ifdef MURMUR3  /* compile w/ -D MURMUR3 to default to this hash */
+
+//-----------------------------------------------------------------------------
+// MurmurHash3 was written by Austin Appleby, and is placed in the public
+// domain. The author hereby disclaims copyright to this source code.
+
+// Note - The x86 and x64 versions do _not_ produce the same results, as the
+// algorithms are optimized for their respective platforms. You can still
+// compile and run any of them on any platform, but your performance with the
+// non-native version will be less than optimal.
+
+//-----------------------------------------------------------------------------
+// Platform-specific functions and macros
+
+// Microsoft Visual Studio
+
+#if defined(_MSC_VER)
+
+#define FORCE_INLINE	__forceinline
+
+#include <stdlib.h>
+
+#define ROTL32(x,y)	_rotl(x,y)
+#define ROTL64(x,y)	_rotl64(x,y)
+
+#define BIG_CONSTANT(x) (x)
+
+// Other compilers
+
+#else	// defined(_MSC_VER)
+
+#define	FORCE_INLINE __attribute__((always_inline))
+
+inline uint32_t rotl32 ( uint32_t x, int8_t r )
+{
+  return (x << r) | (x >> (32 - r));
+}
+
+inline uint64_t rotl64 ( uint64_t x, int8_t r )
+{
+  return (x << r) | (x >> (64 - r));
+}
+
+#define	ROTL32(x,y)	rotl32(x,y)
+#define ROTL64(x,y)	rotl64(x,y)
+
+#define BIG_CONSTANT(x) (x##LLU)
+
+#endif // !defined(_MSC_VER)
+
+//-----------------------------------------------------------------------------
+// Block read - if your platform needs to do endian-swapping or can only
+// handle aligned reads, do the conversion here
+
+FORCE_INLINE uint32_t getblock ( const uint32_t * p, int i )
+{
+  return p[i];
+}
+
+FORCE_INLINE uint64_t getblock ( const uint64_t * p, int i )
+{
+  return p[i];
+}
+
+//-----------------------------------------------------------------------------
+// Finalization mix - force all bits of a hash block to avalanche
+
+FORCE_INLINE uint32_t fmix ( uint32_t h )
+{
+  h ^= h >> 16;
+  h *= 0x85ebca6b;
+  h ^= h >> 13;
+  h *= 0xc2b2ae35;
+  h ^= h >> 16;
+
+  return h;
+}
+
+//
+// ariel: changed the interface to match vw
+// removed all the functions we don't need (leave only the 32-bit hash)
+// renamed MurmurHash3_x86_32 -> uniform_hash
+//
+uint32_t uniform_hash (const void * key, size_t len, uint32_t seed)
+{
+  const uint8_t * data = (const uint8_t*)key;
+  const int nblocks = len / 4;
+
+  uint32_t h1 = seed;
+
+  const uint32_t c1 = 0xcc9e2d51;
+  const uint32_t c2 = 0x1b873593;
+
+  //----------
+  // body
+
+  const uint32_t * blocks = (const uint32_t *)(data + nblocks*4);
+
+  for(int i = -nblocks; i; i++)
+  {
+    uint32_t k1 = getblock(blocks,i);
+
+    k1 *= c1;
+    k1 = ROTL32(k1,15);
+    k1 *= c2;
+    
+    h1 ^= k1;
+    h1 = ROTL32(h1,13); 
+    h1 = h1*5+0xe6546b64;
+  }
+
+  //----------
+  // tail
+
+  const uint8_t * tail = (const uint8_t*)(data + nblocks*4);
+
+  uint32_t k1 = 0;
+
+  switch(len & 3)
+  {
+  case 3: k1 ^= tail[2] << 16;
+  case 2: k1 ^= tail[1] << 8;
+  case 1: k1 ^= tail[0];
+          k1 *= c1; k1 = ROTL32(k1,15); k1 *= c2; h1 ^= k1;
+  };
+
+  //----------
+  // finalization
+
+  h1 ^= len;
+
+  h1 = fmix(h1);
+
+  return h1;
+}
+
+//-----------------------------------------------------------------------------
+
+#else
+
 #define MIX(h,k,m) { k *= m; k ^= k >> r; k *= m; h *= m; h ^= k; }
 
 uint32_t uniform_hash( const void *key, size_t len, uint32_t seed)
@@ -67,3 +219,5 @@ uint32_t uniform_hash( const void *key, size_t len, uint32_t seed)
     return h;
 }
 
+#endif /* MURMUR2 or MURMUR3 */
+