BitMagic-C++
sample3.cpp

Exmaple demonstrates using bitvectors with different initial block allocation strategy.Bitvector 1 (bv1) by default working without RLE compression option (best performance, maximum memory consumption). Bitvector 2 (bv2) will be working in compression mode and use less memory.

See also
bm::bvector<>::set_new_blocks_strat()

For more information please visit: http://bmagic.sourceforge.net

/*
Copyright(c) 2002-2017 Anatoliy Kuznetsov(anatoliy_kuznetsov at yahoo.com)
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
For more information please visit: http://bitmagic.io
*/
/** \example sample3.cpp
Exmaple demonstrates using bitvectors with different initial
block allocation strategy.
Bitvector 1 (bv1) by default working without RLE compression option
(best performance, maximum memory consumption).
Bitvector 2 (bv2) will be working in compression mode and use less memory.
\sa bm::bvector<>::set_new_blocks_strat()
For more information please visit: http://bmagic.sourceforge.net
*/
/*! \file sample3.cpp
\brief Example: bvector<> with different allocation/compression strategies
*/
#include <stdlib.h>
#include <iostream>
#include "bm.h"
#include "bmundef.h" /* clear the pre-proc defines from BM */
using namespace std;
const unsigned MAX_VALUE = 1000000;
// This procedure creates very dense bitvectors.
// The resulting set will consists mostly from ON (1) bits
// interrupted with small gaps of 0 bits.
static
{
for (unsigned i = 0; i < MAX_VALUE; ++i)
{
if (rand() % 2500)
{
bv1->set_bit(i);
bv2->set_bit(i);
}
}
}
static
{
bv.calc_stat(&st);
cout << "Bits count:" << bv.count() << endl;
cout << "Bit blocks:" << st.bit_blocks << endl;
cout << "GAP blocks:" << st.gap_blocks << endl;
cout << "Memory used:"<< st.memory_used << endl;
cout << "Max.serialize mem.:" << st.max_serialize_mem << endl << endl;;
}
int main(void)
{
try
{
bv2.set_new_blocks_strat(bm::BM_GAP); // set DGAP compression mode ON
fill_bvector(&bv1, &bv2); // Fill both bvectors with the same values
// For a given distrubution statistics should demonstrate
// lower memory consumption for the vector with compression
// Now run optimization procedure for bv1 and see statistics.
bv1.optimize();
}
catch(std::exception& ex)
{
std::cerr << ex.what() << std::endl;
}
return 0;
}
Compressed bit-vector bvector<> container, set algebraic methods, traversal iterators.
pre-processor un-defines to avoid global space pollution (internal)
Bitvector Bit-vector container with runtime compression of bits.
Definition: bm.h:115
size_type count() const BMNOEXCEPT
population count (count of ON bits)
Definition: bm.h:2366
void optimize(bm::word_t *temp_block=0, optmode opt_mode=opt_compress, statistics *stat=0)
Optimize memory bitvector's memory allocation.
Definition: bm.h:3600
void set_new_blocks_strat(strategy strat)
Sets new blocks allocation strategy.
Definition: bm.h:1890
bool set_bit(size_type n, bool val=true)
Sets bit n.
Definition: bm.h:4192
void calc_stat(struct bm::bvector< Alloc >::statistics *st) const BMNOEXCEPT
Calculates bitvector statistics.
Definition: bm.h:3943
@ BM_GAP
GAP compression is ON.
Definition: bmconst.h:147
static void print_statistics(const bm::bvector<> &bv)
Definition: sample3.cpp:61
static void fill_bvector(bm::bvector<> *bv1, bm::bvector<> *bv2)
Definition: sample3.cpp:48
int main(void)
Definition: sample3.cpp:74
const unsigned MAX_VALUE
Definition: sample3.cpp:42
size_t gap_blocks
Number of GAP blocks.
Definition: bmfunc.h:58
size_t bit_blocks
Number of bit blocks.
Definition: bmfunc.h:57
size_t max_serialize_mem
estimated maximum memory for serialization
Definition: bmfunc.h:61
size_t memory_used
memory usage for all blocks and service tables
Definition: bmfunc.h:62
Statistical information about bitset's memory allocation details.
Definition: bm.h:125