Odometer.cc

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// -*- mode: c++; c-basic-offset:4 -*-

// This file is part of libdap, A C++ implementation of the OPeNDAP Data
// Access Protocol.

// Copyright (c) 2015 OPeNDAP, Inc.
// Author: James Gallagher <jgallagher@opendap.org>
//
// 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 2.1 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 library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.

#include "config.h"

#include <vector>

#include <Error.h>

#include "Odometer.h"

using namespace std;

namespace libdap {

// documentation in the header file
unsigned int Odometer::next_safe()
{
    if (d_offset == end()) throw Error("Attempt to move beyond the end of an array in the indexing software.");

    // About 3.3 seconds for 10^9 elements
    vector<unsigned int>::reverse_iterator si = d_shape.rbegin();
    for (vector<unsigned int>::reverse_iterator i = d_indices.rbegin(), e = d_indices.rend(); i != e; ++i, ++si) {
        if (++(*i) == *si) {
            *i = 0;
        }
        else {
            break;
        }
    }

    return ++d_offset;
}

#if 0
unsigned int Odometer::next_2()
{
    if (d_offset == end()) throw Error("Attempt to move beyond the end of an array in the indexing software.");

    // ... about 3.5 seconds for this code
    // TODO Unroll this using a switch()
    unsigned int i = d_rank - 1;
    do {
        if (++d_indices[i] == d_shape[i]) {
            d_indices[i] = 0;
        }
        else {
            break;
        }

    } while (i-- > 0);

    return ++d_offset;
}
#endif

} // namespace libdap