hash_utils::MurmurHash3 Class Reference

#include <hash.h>

List of all members.

Public Types
typedef const Byte_t *	MsgPtr_t
typedef UInt_t	Hash_t
typedef Int_t	Length_t
typedef Byte_t	Rot_t
Public Member Functions
	MurmurHash3 (unsigned int seed=0xe086c5ff)
void	Add (MsgPtr_t msg_ptr, Length_t len)
Hash_t	End ()
Private Member Functions
void	MixTail (MsgPtr_t &data, Length_t &len)
UInt_t	rot32 (UInt_t bits, Rot_t r)
void	mmix (Hash_t &h, UInt_t &bits)
void	final_mix (Hash_t &h)
Private Attributes
Hash_t	fHash
UInt_t	fTail
UInt_t	fCount
UInt_t	fSize
Static Private Attributes
static const UInt_t	kMply1 = 0xcc9e2d51
static const UInt_t	kMply2 = 0x1b873593

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Detailed Description

Definition at line 27 of file hash.h.

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Member Typedef Documentation

typedef UInt_t hash_utils::MurmurHash3::Hash_t

Definition at line 30 of file hash.h.

typedef Int_t hash_utils::MurmurHash3::Length_t

Definition at line 31 of file hash.h.

typedef const Byte_t* hash_utils::MurmurHash3::MsgPtr_t

Definition at line 29 of file hash.h.

typedef Byte_t hash_utils::MurmurHash3::Rot_t

Definition at line 32 of file hash.h.

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Constructor & Destructor Documentation

hash_utils::MurmurHash3::MurmurHash3

(

unsigned int

seed = 0xe086c5ff

)

[inline]

Definition at line 34 of file hash.h.

    : fHash(seed), fTail(0), fCount(0), fSize(0)
  {}

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Member Function Documentation

void MurmurHash3::Add	(	MsgPtr_t	msg_ptr,
		Length_t	len
	)

Definition at line 53 of file hash.cpp.

References fHash, fSize, MixTail(), and mmix().

{
  fSize += len;
  
  while(len >= 4) {
    UInt_t k = *(reinterpret_cast<const UInt_t*>(msg_ptr));
    mmix(fHash, k);
    msg_ptr += 4;
    len -= 4;
  }
  
  MixTail(msg_ptr,len);
}

MurmurHash3::Hash_t MurmurHash3::End

(

)

Definition at line 71 of file hash.cpp.

References fHash, final_mix(), fSize, fTail, and mmix().

{
  if (fTail) mmix(fHash, fTail);
  fHash ^= fSize;
  final_mix(fHash);
  return fHash;
}

void hash_utils::MurmurHash3::final_mix

(

Hash_t &

h

)

[inline, private]

Definition at line 55 of file hash.h.

Referenced by End().

  {
    h ^= h >> 16;   h *= 0x85ebca6b;
    h ^= h >> 13;   h *= 0xc2b2ae35;
    h ^= h >> 16;
  }

void MurmurHash3::MixTail	(	MsgPtr_t &	data,
		Length_t &	len
	)			[private]

Definition at line 83 of file hash.cpp.

References fCount, fHash, fTail, and mmix().

Referenced by Add().

{
  while( len && ((len<4) || fCount)) {
    fTail |= (*data++) << (fCount * 8);
    fCount++;
    len--;
    
    if(fCount == 4){
      mmix(fHash, fTail);
      fTail = 0;
      fCount = 0;
    }
  }
}

void hash_utils::MurmurHash3::mmix	(	Hash_t &	h,
		UInt_t &	bits
	)			[inline, private]

Definition at line 49 of file hash.h.

References kMply1, kMply2, and rot32().

Referenced by Add(), End(), and MixTail().

  { 
    bits *= kMply1;   bits = rot32(bits, 15);   bits *= kMply2;
    h ^= bits;   h = rot32(h, 13) * 5 + 0xe6546b64;
  }

UInt_t hash_utils::MurmurHash3::rot32	(	UInt_t	bits,
		Rot_t	r
	)			[inline, private]

Definition at line 44 of file hash.h.

Referenced by mmix().

  {
    return (bits << r) | (bits >> (32 - r));
  }

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Member Data Documentation

UInt_t hash_utils::MurmurHash3::fCount [private]

Definition at line 72 of file hash.h.

Referenced by MixTail().

Hash_t hash_utils::MurmurHash3::fHash [private]

Definition at line 70 of file hash.h.

Referenced by Add(), End(), and MixTail().

UInt_t hash_utils::MurmurHash3::fSize [private]

Definition at line 73 of file hash.h.

Referenced by Add(), and End().

UInt_t hash_utils::MurmurHash3::fTail [private]

Definition at line 71 of file hash.h.

Referenced by End(), and MixTail().

const UInt_t hash_utils::MurmurHash3::kMply1 = 0xcc9e2d51 [static, private]

Definition at line 62 of file hash.h.

Referenced by mmix().

const UInt_t hash_utils::MurmurHash3::kMply2 = 0x1b873593 [static, private]

Definition at line 63 of file hash.h.

Referenced by mmix().

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The documentation for this class was generated from the following files:

• rootana/src/framework/hash.h
• rootana/src/framework/hash.cpp