utils/log2.cpp

Go to the documentation of this file.

/***************************************************************************
 *  utils/log2.cpp
 *
 *  Part of the STXXL. See http://stxxl.sourceforge.net
 *
 *  Copyright © 2008 Andreas Beckmann <beckmann@cs.uni-frankfurt.de>
 *
 *  Distributed under the Boost Software License, Version 1.0.
 *  (See accompanying file LICENSE_1_0.txt or copy at
 *  http://www.boost.org/LICENSE_1_0.txt)
 **************************************************************************/

#include <iostream>
#include <stxxl.h>

using stxxl::LOG2;
using stxxl::unsigned_type;

template <unsigned_type i>
void log_i()
{
    std::cout << i << "\t" << (i < 1000000 ? "\t" : "")
              << stxxl::LOG2_floor<i>::value << "\t"
              << stxxl::LOG2<i>::floor << "\t"
              << stxxl::LOG2<i>::ceil << std::endl;
}

template <unsigned_type i>
void log_ipm1()
{
    log_i<i - 1>();
    log_i<i>();
    log_i<i + 1>();
    std::cout << std::endl;
}

int main()
{
    std::cout << "i\t\tLOG2<i>\tLOG2<i>\tLOG2<i>" << std::endl;
    std::cout << "\t\t\tfloor\tceil" << std::endl;
    log_ipm1<1 << 0>();
    log_ipm1<1 << 1>();
    log_ipm1<1 << 2>();
    log_ipm1<1 << 3>();
    log_ipm1<1 << 4>();
    log_ipm1<1 << 5>();
    log_ipm1<1 << 6>();
    log_ipm1<1 << 7>();
    log_ipm1<1 << 8>();
    log_ipm1<1 << 9>();
    log_ipm1<1 << 10>();
    log_ipm1<1 << 11>();
    log_ipm1<1 << 12>();
    log_ipm1<1 << 16>();
    log_ipm1<1 << 24>();
    log_ipm1<1 << 30>();
    log_ipm1<1UL << 31>();
#if __WORDSIZE == 64
    log_ipm1<1UL << 32>();
    log_ipm1<1UL << 33>();
    log_ipm1<1UL << 48>();
    log_ipm1<1UL << 63>();
#endif
}