humanize_number.c

   1 /*      $NetBSD: humanize_number.c,v 1.14 2008/04/28 20:22:59 martin Exp $      */
   2
   3 /*
   4  * Copyright (c) 1997, 1998, 1999, 2002 The NetBSD Foundation, Inc.
   5  * Copyright 2013 John-Mark Gurney <jmg@FreeBSD.org>
   6  * All rights reserved.
   7  *
   8  * This code is derived from software contributed to The NetBSD Foundation
   9  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
  10  * NASA Ames Research Center, by Luke Mewburn and by Tomas Svensson.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  23  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  25  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include <sys/types.h>
  38 #include <assert.h>
  39 #include <inttypes.h>
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <locale.h>
  44 #include <libutil.h>
  45
  46 static const int maxscale = 7;
  47
  48 int
  49 humanize_number(char *buf, size_t len, int64_t quotient,
  50     const char *suffix, int scale, int flags)
  51 {
  52         const char *prefixes, *sep;
  53         int     i, r, remainder, s1, s2, sign;
  54         int     divisordeccut;
  55         int64_t divisor, max;
  56         size_t  baselen;
  57
  58         /* Since so many callers don't check -1, NUL terminate the buffer */
  59         if (len > 0)
  60                 buf[0] = '\0';
  61
  62         /* validate args */
  63         if (buf == NULL || suffix == NULL)
  64                 return (-1);
  65         if (scale < 0)
  66                 return (-1);
  67         else if (scale >= maxscale &&
  68             ((scale & ~(HN_AUTOSCALE|HN_GETSCALE)) != 0))
  69                 return (-1);
  70         if ((flags & HN_DIVISOR_1000) && (flags & HN_IEC_PREFIXES))
  71                 return (-1);
  72
  73         /* setup parameters */
  74         remainder = 0;
  75
  76         if (flags & HN_IEC_PREFIXES) {
  77                 baselen = 2;
  78                 /*
  79                  * Use the prefixes for power of two recommended by
  80                  * the International Electrotechnical Commission
  81                  * (IEC) in IEC 80000-3 (i.e. Ki, Mi, Gi...).
  82                  *
  83                  * HN_IEC_PREFIXES implies a divisor of 1024 here
  84                  * (use of HN_DIVISOR_1000 would have triggered
  85                  * an assertion earlier).
  86                  */
  87                 divisor = 1024;
  88                 divisordeccut = 973;    /* ceil(.95 * 1024) */
  89                 if (flags & HN_B)
  90                         prefixes = "B\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
  91                 else
  92                         prefixes = "\0\0\0Ki\0Mi\0Gi\0Ti\0Pi\0Ei";
  93         } else {
  94                 baselen = 1;
  95                 if (flags & HN_DIVISOR_1000) {
  96                         divisor = 1000;
  97                         divisordeccut = 950;
  98                         if (flags & HN_B)
  99                                 prefixes = "B\0\0k\0\0M\0\0G\0\0T\0\0P\0\0E";
 100                         else
 101                                 prefixes = "\0\0\0k\0\0M\0\0G\0\0T\0\0P\0\0E";
 102                 } else {
 103                         divisor = 1024;
 104                         divisordeccut = 973;    /* ceil(.95 * 1024) */
 105                         if (flags & HN_B)
 106                                 prefixes = "B\0\0K\0\0M\0\0G\0\0T\0\0P\0\0E";
 107                         else
 108                                 prefixes = "\0\0\0K\0\0M\0\0G\0\0T\0\0P\0\0E";
 109                 }
 110         }
 111
 112 #define SCALE2PREFIX(scale)     (&prefixes[(scale) * 3])
 113
 114         if (quotient < 0) {
 115                 sign = -1;
 116                 quotient = -quotient;
 117                 baselen += 2;           /* sign, digit */
 118         } else {
 119                 sign = 1;
 120                 baselen += 1;           /* digit */
 121         }
 122         if (flags & HN_NOSPACE)
 123                 sep = "";
 124         else {
 125                 sep = " ";
 126                 baselen++;
 127         }
 128         baselen += strlen(suffix);
 129
 130         /* Check if enough room for `x y' + suffix + `\0' */
 131         if (len < baselen + 1)
 132                 return (-1);
 133
 134         if (scale & (HN_AUTOSCALE | HN_GETSCALE)) {
 135                 /* See if there is additional columns can be used. */
 136                 for (max = 1, i = len - baselen; i-- > 0 && max <= (INT64_MAX / 10);)
 137                         max *= 10;
 138
 139                 /*
 140                  * Divide the number until it fits the given column.
 141                  * If there will be an overflow by the rounding below,
 142                  * divide once more.
 143                  */
 144                 for (i = 0;
 145                     (quotient >= max || (quotient == max - 1 &&
 146                     remainder >= divisordeccut)) && i < maxscale; i++) {
 147                         remainder = quotient % divisor;
 148                         quotient /= divisor;
 149                 }
 150
 151                 if (scale & HN_GETSCALE)
 152                         return (i);
 153         } else {
 154                 for (i = 0; i < scale && i < maxscale; i++) {
 155                         remainder = quotient % divisor;
 156                         quotient /= divisor;
 157                 }
 158         }
 159
 160         /* If a value <= 9.9 after rounding and ... */
 161         /*
 162          * XXX - should we make sure there is enough space for the decimal
 163          * place and if not, don't do HN_DECIMAL?
 164          */
 165         if (((quotient == 9 && remainder < divisordeccut) || quotient < 9) &&
 166             i > 0 && flags & HN_DECIMAL) {
 167                 s1 = (int)quotient + ((remainder * 10 + divisor / 2) /
 168                     divisor / 10);
 169                 s2 = ((remainder * 10 + divisor / 2) / divisor) % 10;
 170                 r = snprintf(buf, len, "%d%s%d%s%s%s",
 171                     sign * s1, localeconv()->decimal_point, s2,
 172                     sep, SCALE2PREFIX(i), suffix);
 173         } else
 174                 r = snprintf(buf, len, "%" PRId64 "%s%s%s",
 175                     sign * (quotient + (remainder + divisor / 2) / divisor),
 176                     sep, SCALE2PREFIX(i), suffix);
 177
 178         return (r);
 179 }