int izstream::underflow ( )

inlineprivate

Definition at line 23 of file izstream.h.

References is_open().

    {
        if (gptr() && gptr()<egptr())
            return * reinterpret_cast<unsigned char *>(gptr());

        if (!is_open())
            return EOF;

        // gptr()-eback(): if more than four bytes are already flushed
        const int iputback = gptr()-eback()>4 ? 4 : gptr()-eback();

        // Copy the last four bytes flushed into the putback area
        memcpy(fBuffer+(4-iputback), gptr()-iputback, iputback);

        // Fill the buffer starting at the current file position and reset buffer
        // pointers by calling setg
        const int num = gzread(fFile, fBuffer+4, fgBufferSize-4);
        if (num <= 0) // ERROR or EOF
            return EOF;

        // reset buffer pointers
        setg(fBuffer+(4-iputback), fBuffer+4, fBuffer+4+num);

        // return next character
        return *reinterpret_cast<unsigned char *>(gptr());
    }

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