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-rw-r--r--src/lib/libc/stdlib/gcvt.c108
1 files changed, 108 insertions, 0 deletions
diff --git a/src/lib/libc/stdlib/gcvt.c b/src/lib/libc/stdlib/gcvt.c
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+++ b/src/lib/libc/stdlib/gcvt.c
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1/* $OpenBSD: gcvt.c,v 1.9 2006/01/10 16:18:37 millert Exp $ */
2
3/*
4 * Copyright (c) 2002, 2003, 2006 Todd C. Miller <Todd.Miller@courtesan.com>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 *
18 * Sponsored in part by the Defense Advanced Research Projects
19 * Agency (DARPA) and Air Force Research Laboratory, Air Force
20 * Materiel Command, USAF, under agreement number F39502-99-1-0512.
21 */
22
23#include <locale.h>
24#include <stdio.h>
25#include <stdlib.h>
26#include <string.h>
27
28extern char *__dtoa(double, int, int, int *, int *, char **);
29
30char *
31gcvt(double value, int ndigit, char *buf)
32{
33 char *digits, *dst, *src;
34 int i, decpt, sign;
35 struct lconv *lconv;
36
37 lconv = localeconv();
38 if (ndigit == 0) {
39 buf[0] = '\0';
40 return (buf);
41 }
42
43 digits = __dtoa(value, 2, ndigit, &decpt, &sign, NULL);
44 if (decpt == 9999) {
45 /*
46 * Infinity or NaN, convert to inf or nan with sign.
47 * We assume the buffer is at least ndigit long.
48 */
49 snprintf(buf, ndigit + 1, "%s%s", sign ? "-" : "",
50 *digits == 'I' ? "inf" : "nan");
51 return (buf);
52 }
53
54 dst = buf;
55 if (sign)
56 *dst++ = '-';
57
58 if (decpt < 0 || decpt > ndigit) {
59 /* exponential format (e.g. 1.2345e+13) */
60 if (--decpt < 0) {
61 sign = 1;
62 decpt = -decpt;
63 } else
64 sign = 0;
65 src = digits;
66 *dst++ = *src++;
67 *dst++ = *lconv->decimal_point;
68 while (*src != '\0')
69 *dst++ = *src++;
70 *dst++ = 'e';
71 if (sign)
72 *dst++ = '-';
73 else
74 *dst++ = '+';
75 if (decpt < 10) {
76 *dst++ = '0';
77 *dst++ = '0' + decpt;
78 *dst = '\0';
79 } else {
80 /* XXX - optimize */
81 for (sign = decpt, i = 0; (sign /= 10) != 0; i++)
82 continue;
83 dst[i + 1] = '\0';
84 while (decpt != 0) {
85 dst[i--] = '0' + decpt % 10;
86 decpt /= 10;
87 }
88 }
89 } else {
90 /* standard format */
91 for (i = 0, src = digits; i < decpt; i++) {
92 if (*src != '\0')
93 *dst++ = *src++;
94 else
95 *dst++ = '0';
96 }
97 if (*src != '\0') {
98 if (src == digits)
99 *dst++ = '0'; /* zero before decimal point */
100 *dst++ = *lconv->decimal_point;
101 for (i = decpt; digits[i] != '\0'; i++) {
102 *dst++ = digits[i];
103 }
104 }
105 *dst = '\0';
106 }
107 return (buf);
108}