bitmap_digest.h

这是一个著名的应用层组播中间件的源码

//Copyright (c) 2004, Charles Killian, Adolfo Rodriguez, Dejan Kostic, Sooraj Bhat, and Amin Vahdat
//All rights reserved.
//
//Redistribution and use in source and binary forms, with or without
//modification, are permitted provided that the following conditions are met:
//
//   * Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in
//     the documentation and/or other materials provided with the
//     distribution.
//   * Neither the names of Duke University nor The University of
//     California, San Diego, nor the names of its contributors
//     may be used to endorse or promote products derived from
//     this software without specific prior written permission.
//
//THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
//AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
//IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
//DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
//FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
//DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
//SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
//CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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//USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef __bitmap_digest
#define __bitmap_digest
#include "digest.h"

//const static int BITMAP_SIZE = 1024*22;
const static int BITMAP_SIZE = 1024*6; //was *4

typedef struct bitmapy {
  int tab_size;
  int start_bit;
  int start_seq;
  int last_seq;
#if VARIABLE_BITMAP
  unsigned char* tab;
  bitmapy():tab( 0) {}
  int  size_core_in_bytes (){sizeof(*this)-sizeof(unsigned char* );};
#else
  unsigned char tab[BITMAP_SIZE/8]; 
#endif
} flat_bitmap;

class bitmap_digest : public digest
	{
	
public:
 bitmap_digest	(int size = BITMAP_SIZE);
~bitmap_digest	( );
public:
  bool  contains (int item);
  //insert returns the lowest sequence number remaining in the  digest even after truncation
  int  insert (int item, int suppress = 1);
  //returns 1 if it actually cleared the bit (i.e. it was in range)
  int  remove_item (int item);
  void   serialize (unsigned char* buffer);
  void  import (unsigned char* buffer);
  int  size_compacted_in_bytes ();
  int  reset ();
  int  get_lowest_sequence ();
  int  get_highest_sequence ();

  flat_bitmap bm;
 protected:
  int in_table (int seq);
  int  which_byte  (int seq);
  int  which_bit  (int seq);
  void set_bit (int seq, int set_value);

 private:
 	};
#endif //__bitmap_digest