ReadHex.C

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    Copyright (C) 2013-2015 OpenFOAM Foundation
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License
    This file is part of OpenFOAM.

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    under the terms of the GNU General Public License as published by
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Description
    Read a non-delimited hex label

\*---------------------------------------------------------------------------*/

#include "ReadHex.H"
#include <cctype>

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

template<class T>
T Foam::ReadHex(ISstream& is)
{
    // The char '0' == 0
    static constexpr int offsetZero = int('0');

    // The char 'A' (or 'a') == 10
    static constexpr int offsetAlpha = int('A') - 10;

    char c = 0;

    // Get next non-whitespace character
    while (is.get(c) && isspace(c))
    {}

    T result = 0;
    do
    {
        if (isspace(c) || c == 0) break;

        if (!isxdigit(c))
        {
            FatalIOErrorInFunction(is)
                << "Illegal hex digit: '" << c << "'"
                << exit(FatalIOError);
        }

        result <<= 4;

        if (isdigit(c))
        {
            result += int(c) - offsetZero;
        }
        else
        {
            result += toupper(c) - offsetAlpha;
        }
    } while (is.get(c));

    return result;
}


// ************************************************************************* //