nearzero.c

/* nearzero.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.  (COPYING.LIB)

    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 <config.h>
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdarg.h>
#include "bcmath.h"
#include "private.h"

/* In some places we need to check if the number NUM is almost zero.
   Specifically, all but the last digit is 0 and the last digit is 1.
   Last digit is defined by scale. */

char
bc_is_near_zero (num, scale)
     bc_num num;
     int scale;
{
  int  count;
  char *nptr;

  /* Error checking */
  if (scale > num->n_scale)
    scale = num->n_scale;

  /* Initialize */
  count = num->n_len + scale;
  nptr = num->n_value;

  /* The check */
  while ((count > 0) && (*nptr++ == 0)) count--;

  if (count != 0 && (count != 1 || *--nptr != 1))
    return FALSE;
  else
    return TRUE;
}