124 lines
3.0 KiB
C
124 lines
3.0 KiB
C
/* $OpenBSD: gcvt.c,v 1.15 2022/12/27 17:10:06 jmc Exp $ */
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/*
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* Copyright (c) 2002, 2003, 2006, 2010
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* Todd C. Miller <millert@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* Sponsored in part by the Defense Advanced Research Projects
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* Agency (DARPA) and Air Force Research Laboratory, Air Force
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* Materiel Command, USAF, under agreement number F39502-99-1-0512.
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*/
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#include <locale.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "gdtoa.h"
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#define DEFPREC 6
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char *
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gcvt(double value, int ndigit, char *buf)
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{
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char *digits, *dst, *src;
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int i, decpt, sign;
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struct lconv *lconv;
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lconv = localeconv();
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if (ndigit <= 0) {
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/* Match printf(3) behavior. */
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ndigit = ndigit ? DEFPREC : 1;
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}
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digits = __dtoa(value, 2, ndigit, &decpt, &sign, NULL);
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if (digits == NULL)
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return (NULL);
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if (decpt == 9999) {
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/*
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* Infinity or NaN, convert to inf or nan with sign.
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* We can't infer buffer size based on ndigit.
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* We have to assume it is at least 5 chars.
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*/
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snprintf(buf, 5, "%s%s", sign ? "-" : "",
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*digits == 'I' ? "inf" : "nan");
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__freedtoa(digits);
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return (buf);
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}
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dst = buf;
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if (sign)
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*dst++ = '-';
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/* Match printf(3) behavior for exponential vs. regular formatting. */
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if (decpt <= -4 || decpt > ndigit) {
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/* exponential format (e.g. 1.2345e+13) */
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if (--decpt < 0) {
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sign = 1;
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decpt = -decpt;
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} else
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sign = 0;
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src = digits;
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*dst++ = *src++;
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if (*src != '\0') {
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*dst++ = *lconv->decimal_point;
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do {
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*dst++ = *src++;
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} while (*src != '\0');
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}
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*dst++ = 'e';
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if (sign)
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*dst++ = '-';
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else
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*dst++ = '+';
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if (decpt < 10) {
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*dst++ = '0';
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*dst++ = '0' + decpt;
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*dst = '\0';
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} else {
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/* XXX - optimize */
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for (sign = decpt, i = 0; (sign /= 10) != 0; i++)
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continue;
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dst[i + 1] = '\0';
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while (decpt != 0) {
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dst[i--] = '0' + decpt % 10;
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decpt /= 10;
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}
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}
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} else {
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/* standard format */
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for (i = 0, src = digits; i < decpt; i++) {
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if (*src != '\0')
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*dst++ = *src++;
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else
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*dst++ = '0';
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}
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if (*src != '\0') {
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if (src == digits)
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*dst++ = '0'; /* zero before decimal point */
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*dst++ = *lconv->decimal_point;
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while (decpt < 0) {
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*dst++ = '0';
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decpt++;
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}
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for (i = decpt; digits[i] != '\0'; i++) {
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*dst++ = digits[i];
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}
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}
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*dst = '\0';
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}
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__freedtoa(digits);
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return (buf);
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}
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