csh/strpct.c

   1 /*      $NetBSD: strpct.c,v 1.2 1998/05/08 18:43:54 fair Exp $  */
   2
   3 /*-
   4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Erik E. Fair
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *        This product includes software developed by the NetBSD
  21  *        Foundation, Inc. and its contributors.
  22  * 4. Neither the name of The NetBSD Foundation nor the names of its
  23  *    contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  36  * POSSIBILITY OF SUCH DAMAGE.
  37  */
  38
  39 /*
  40  * Calculate a percentage without resorting to floating point
  41  * and return a pointer to a string
  42  *
  43  * "digits" is the number of digits past the decimal place you want
  44  * (zero being the straight percentage with no decimals)
  45  *
  46  * Erik E. Fair <fair@clock.org>, May 8, 1997
  47  */
  48
  49 #include <sys/types.h>
  50 #include <machine/limits.h>
  51
  52 #include <stdio.h>
  53
  54 char * strpct __P((u_long, u_long, u_int));
  55
  56 char *
  57 strpct(numerator, denominator, digits)
  58         u_long  numerator, denominator;
  59         u_int   digits;
  60 {
  61         int i;
  62         u_long result, factor;
  63         static char     percent[32];
  64
  65         /* I should check for digit overflow here, too XXX */
  66         factor = 100L;
  67         for(i = 0; i < digits; i++) {
  68                 factor *= 10;
  69         }
  70
  71         /* watch out for overflow! */
  72         if (numerator < (ULONG_MAX / factor)) {
  73                 numerator *= factor;
  74         } else {
  75                 /* toss some of the bits of lesser significance */
  76                 denominator /= factor;
  77         }
  78
  79         if (denominator == 0L)
  80                 denominator = 1L;
  81
  82         result = numerator / denominator;
  83
  84         if (digits == 0) {
  85                 (void) snprintf(percent, sizeof(percent), "%lu%%", result);
  86         } else {
  87                 char    fmt[32];
  88
  89                 /* indirection to produce the right output format */
  90                 (void) snprintf(fmt, sizeof(fmt), "%%lu.%%0%ulu%%%%", digits);
  91
  92                 factor /= 100L;         /* undo initialization */
  93
  94                 (void) snprintf(percent, sizeof(percent),
  95                         fmt, result / factor, result % factor);
  96         }
  97
  98         return(percent);
  99 }