text: /*	$NetBSD: humanize_number.c,v 1.14 2008/04/28 20:22:59 martin Exp $	*/
  
  /*
   * Copyright (c) 1997, 1998, 1999, 2002 The NetBSD Foundation, Inc.
   * Copyright 2013 John-Mark Gurney <jmg@FreeBSD.org>
   * All rights reserved.
   *
   * This code is derived from software contributed to The NetBSD Foundation
   * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
   * NASA Ames Research Center, by Luke Mewburn and by Tomas Svensson.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD$");
  
  #include <sys/types.h>
  #include <assert.h>
  #include <inttypes.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <locale.h>
  #include <libutil.h>
  
  static const int maxscale = 7;
  
  int
  humanize_number(char *buf, size_t len, int64_t quotient,
      const char *suffix, int scale, int flags)
  {
  	const char *prefixes, *sep;
  	int	i, r, remainder, s1, s2, sign;
  	int	divisordeccut;
  	int64_t	divisor, max;
  	size_t	baselen;
  
  	/* Since so many callers don't check -1, NUL terminate the buffer */
  	if (len > 0)
  		buf[0] = '\0';
  
  	/* validate args */
  	if (buf == NULL || suffix == NULL)
  		return (-1);
  	if (scale < 0)
  		return (-1);
  	else if (scale >= maxscale &&
  	    ((scale & ~(HN_AUTOSCALE|HN_GETSCALE)) != 0))
  		return (-1);
  	if ((flags & HN_DIVISOR_1000) && (flags & HN_IEC_PREFIXES))
  		return (-1);
  
  	/* setup parameters */
  	remainder = 0;
  
  	if (flags & HN_IEC_PREFIXES) {
  		baselen = 2;
  		/*
  		 * Use the prefixes for power of two recommended by
  		 * the International Electrotechnical Commission
  		 * (IEC) in IEC 80000-3 (i.e. Ki, Mi, Gi...).
  		 *
  		 * HN_IEC_PREFIXES implies a divisor of 1024 here
  		 * (use of HN_DIVISOR_1000 would have triggered
  		 * an assertion earlier).
  		 */
  		divisor = 1024;
  		divisordeccut = 973;	/* ceil(.95 * 1024) */
  		if (flags & HN_B)
  			prefixes = "B\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
  		else
  			prefixes = "\0\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
  	} else {
  		baselen = 1;
  		if (flags & HN_DIVISOR_1000) {
  			divisor = 1000;
  			divisordeccut = 950;
  			if (flags & HN_B)
  				prefixes = "B\0\0k\0\0M\0\0G\0\0T\0\0P\0\0E";
  			else
  				prefixes = "\0\0\0k\0\0M\0\0G\0\0T\0\0P\0\0E";
  		} else {
  			divisor = 1024;
  			divisordeccut = 973;	/* ceil(.95 * 1024) */
  			if (flags & HN_B)
  				prefixes = "B\0\0K\0\0M\0\0G\0\0T\0\0P\0\0E";
  			else
  				prefixes = "\0\0\0K\0\0M\0\0G\0\0T\0\0P\0\0E";
  		}
  	}
  
  #define	SCALE2PREFIX(scale)	(&prefixes[(scale) * 3])
  
  	if (quotient < 0) {
  		sign = -1;
  		quotient = -quotient;
  		baselen += 2;		/* sign, digit */
  	} else {
  		sign = 1;
  		baselen += 1;		/* digit */
  	}
  	if (flags & HN_NOSPACE)
  		sep = "";
  	else {
  		sep = " ";
  		baselen++;
  	}
  	baselen += strlen(suffix);
  
  	/* Check if enough room for `x y' + suffix + `\0' */
  	if (len < baselen + 1)
  		return (-1);
  
  	if (scale & (HN_AUTOSCALE | HN_GETSCALE)) {
  		/* See if there is additional columns can be used. */
  		for (max = 1, i = len - baselen; i-- > 0;)
  			max *= 10;
  
  		/*
  		 * Divide the number until it fits the given column.
  		 * If there will be an overflow by the rounding below,
  		 * divide once more.
  		 */
  		for (i = 0;
  		    (quotient >= max || (quotient == max - 1 &&
  		    remainder >= divisordeccut)) && i < maxscale; i++) {
  			remainder = quotient % divisor;
  			quotient /= divisor;
  		}
  
  		if (scale & HN_GETSCALE)
  			return (i);
  	} else {
  		for (i = 0; i < scale && i < maxscale; i++) {
  			remainder = quotient % divisor;
  			quotient /= divisor;
  		}
  	}
  
  	/* If a value <= 9.9 after rounding and ... */
  	/*
  	 * XXX - should we make sure there is enough space for the decimal
  	 * place and if not, don't do HN_DECIMAL?
  	 */
  	if (((quotient == 9 && remainder < divisordeccut) || quotient < 9) &&
  	    i > 0 && flags & HN_DECIMAL) {
  		s1 = (int)quotient + ((remainder * 10 + divisor / 2) /
  		    divisor / 10);
  		s2 = ((remainder * 10 + divisor / 2) / divisor) % 10;
  		r = snprintf(buf, len, "%d%s%d%s%s%s",
  		    sign * s1, localeconv()->decimal_point, s2,
  		    sep, SCALE2PREFIX(i), suffix);
  	} else
  		r = snprintf(buf, len, "%" PRId64 "%s%s%s",
  		    sign * (quotient + (remainder + divisor / 2) / divisor),
  		    sep, SCALE2PREFIX(i), suffix);
  
  	return (r);
  }
  