1 /* $OpenBSD: gcvt.c,v 1.1 2002/12/02 15:38:54 millert Exp $ */ 2 3 /* 4 * Copyright (c) 2002 Todd C. Miller <Todd.Miller@courtesan.com> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 19 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 20 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 21 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 22 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 23 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 24 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 26 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 27 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #if defined(LIBC_SCCS) && !defined(lint) 31 static char rcsid[] = "$OpenBSD: gcvt.c,v 1.1 2002/12/02 15:38:54 millert Exp $"; 32 #endif /* LIBC_SCCS and not lint */ 33 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <string.h> 37 38 extern char *__dtoa(double, int, int, int *, int *, char **); 39 40 char * 41 gcvt(double value, int ndigit, char *buf) 42 { 43 char *digits, *dst, *src; 44 int i, decpt, sign; 45 46 if (ndigit == 0) { 47 buf[0] = '\0'; 48 return (buf); 49 } 50 51 digits = __dtoa(value, 2, ndigit, &decpt, &sign, NULL); 52 if (decpt == 9999) 53 return (strcpy(buf, digits)); 54 55 dst = buf; 56 if (sign) 57 *dst++ = '-'; 58 59 if (decpt < 0 || decpt > ndigit) { 60 /* exponential format */ 61 if (--decpt < 0) { 62 sign = 1; 63 decpt = -decpt; 64 } else 65 sign = 0; 66 for (src = digits; *src != '\0'; ) 67 *dst++ = *src++; 68 *dst++ = 'e'; 69 if (sign) 70 *dst++ = '-'; 71 else 72 *dst++ = '+'; 73 if (decpt < 10) { 74 *dst++ = '0'; 75 *dst++ = '0' + decpt; 76 *dst = '\0'; 77 } else { 78 /* XXX - optimize */ 79 for (sign = decpt, i = 0; (sign /= 10) != 0; i++) 80 sign /= 10; 81 while (decpt != 0) { 82 dst[i--] = '0' + decpt % 10; 83 decpt /= 10; 84 } 85 } 86 } else { 87 /* standard format */ 88 for (i = 0, src = digits; i < decpt; i++) { 89 if (*src != '\0') 90 *dst++ = *src++; 91 else 92 *dst++ = '0'; 93 } 94 if (*src != '\0') { 95 *dst++ = '.'; /* XXX - locale-specific (LC_NUMERIC) */ 96 for (i = decpt; digits[i] != '\0'; i++) { 97 *dst++ = digits[i]; 98 } 99 } 100 *dst = '\0'; 101 } 102 return (buf); 103 } 104