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 54char * strpct __P((u_long, u_long, u_int)); 55 56char * 57strpct(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} 100