/* num2long.c: bcmath library file. */
/*
    Copyright (C) 1991, 1992, 1993, 1994, 1997 Free Software Foundation, Inc.
    Copyright (C) 2000 Philip A. Nelson

    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 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.  (LICENSE)

    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.
      59 Temple Place, Suite 330
      Boston, MA 02111-1307 USA.

    You may contact the author by:
       e-mail:  philnelson@acm.org
      us-mail:  Philip A. Nelson
                Computer Science Department, 9062
                Western Washington University
                Bellingham, WA 98226-9062

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

#include "bcmath.h"
#include <stddef.h>

/* Convert a number NUM to a long.  The function returns only the integer
   part of the number.  For numbers that are too large to represent as
   a long, this function returns a zero.  This can be detected by checking
   the NUM for zero after having a zero returned. */

long bc_num2long(bc_num num)
{
	/* Extract the int value, ignore the fraction. */
	long val = 0;
	const char *nptr = num->n_value;
	for (size_t index = num->n_len; index > 0; index--) {
		char n = *nptr++;

		if (val > LONG_MAX / BASE) {
			return 0;
		}
		val *= BASE;

		if (val > LONG_MAX - n) {
			return 0;
		}
		val += n;
	}

	/* Return the value. */
	if (num->n_sign == PLUS) {
		return (val);
	} else {
		return (-val);
	}
}