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/*
* Sux: Succinct data structures
*
* Copyright (C) 2007-2013 Sebastiano Vigna
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 3 of the License, or (at your option)
* any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include <cassert>
#include <cstring>
#include "rank9b.h"
rank9b::rank9b() {}
rank9b::rank9b( const uint64_t * const bits, const uint64_t num_bits ) {
this->bits = bits;
num_words = ( num_bits + 63 ) / 64;
num_counts = ( ( num_bits + 64 * 8 - 1 ) / ( 64 * 8 ) ) * 2;
// Init rank structure
counts = new uint64_t[ num_counts + 1 ];
memset( counts, 0, ( num_counts + 1 ) * sizeof *counts );
uint64_t c = 0;
uint64_t pos = 0;
for( uint64_t i = 0; i < num_words; i += 8, pos += 2 ) {
counts[ pos ] = c;
c += __builtin_popcountll( bits[ i ] );
for( int j = 1; j < 8; j++ ) {
counts[ pos + 1 ] |= ( c - counts[ pos ] ) << 63 - 9 * j;
if ( i + j < num_words ) c += __builtin_popcountll( bits[ i + j ] );
}
}
counts[ num_counts ] = c;
assert( c <= num_bits );
}
rank9b::~rank9b() {
delete [] counts;
}
uint64_t rank9b::rank( const uint64_t k ) {
const uint64_t word = k / 64;
const uint64_t block = word / 4 & ~1;
const int offset = word % 8;
return counts[ block ] + ( counts[ block + 1 ] >> ( 63 - offset * 9 ) & 0x1FF ) + __builtin_popcountll( bits[ word ] & ( ( 1ULL << k % 64 ) - 1 ) );
}
uint64_t rank9b::bit_count() {
return num_counts * 64;
}
void rank9b::print_counts() {}
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