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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1988 AT&T */
/* All Rights Reserved */
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* ecvt converts to decimal
* the number of digits is specified by ndigit
* decpt is set to the position of the decimal point
* sign is set to 0 for positive, 1 for negative
*
*/
#pragma weak _ecvt = ecvt
#pragma weak _fcvt = fcvt
#include "lint.h"
#include <sys/types.h>
#include <values.h>
#include <nan.h>
#include <string.h>
#include "tsd.h"
#define NMAX ((DSIGNIF * 3 + 19)/10) /* restrict max precision */
#define NDIG 80
static char *cvt(double, int, int *, int *, int);
char *
ecvt(double value, int ndigit, int *decpt, int *sign)
{
return (cvt(value, ndigit, decpt, sign, 0));
}
char *
fcvt(double value, int ndigit, int *decpt, int *sign)
{
return (cvt(value, ndigit, decpt, sign, 1));
}
static char *
cvt(double value, int ndigit, int *decpt, int *sign, int f_flag)
{
char *buf = tsdalloc(_T_ECVT, NDIG, NULL);
char *p = &buf[0], *p_last = &buf[ndigit];
buf[0] = '\0';
if (IsNANorINF(value)) {
if (IsINF(value)) /* value is an INF, return "inf" */
(void) strncpy(buf, "inf", NDIG);
else /* value is a NaN, return "NaN" */
(void) strncpy(buf, "nan", NDIG);
return (buf);
}
if ((*sign = (value < 0.0)) != 0)
value = -value;
*decpt = 0;
if (value != 0.0) {
/*
* rescale to range [1.0, 10.0)
* in binary for speed and to minimize error build-up
* even for the IEEE standard with its high exponents,
* it's probably better for speed to just loop on them
*/
static const struct s { double p10; int n; } s[] = {
1e32, 32,
1e16, 16,
1e8, 8,
1e4, 4,
1e2, 2,
1e1, 1,
};
const struct s *sp = s;
++*decpt;
if (value >= 2.0 * MAXPOWTWO) /* can't be precisely integral */
do {
for (; value >= sp->p10; *decpt += sp->n)
value /= sp->p10;
} while (sp++->n > 1);
else if (value >= 10.0) { /* convert integer part separately */
double pow10 = 10.0, powtemp;
while ((powtemp = 10.0 * pow10) <= value)
pow10 = powtemp;
for (; ; pow10 /= 10.0) {
int digit = value/pow10;
*p++ = digit + '0';
value -= digit * pow10;
++*decpt;
if (pow10 <= 10.0)
break;
}
} else if (value < 1.0)
do {
for (; value * sp->p10 < 10.0; *decpt -= sp->n)
value *= sp->p10;
} while (sp++->n > 1);
}
if (f_flag)
p_last += *decpt;
if (p_last >= buf) {
if (p_last > &buf[NDIG - 2])
p_last = &buf[NDIG - 2];
for (; ; ++p) {
if (value == 0 || p >= &buf[NMAX])
*p = '0';
else {
int intx; /* intx in [0, 9] */
*p = (intx = (int)value) + '0';
value = 10.0 * (value - (double)intx);
}
if (p >= p_last) {
p = p_last;
break;
}
}
if (*p >= '5') /* check rounding in last place + 1 */
do {
if (p == buf) { /* rollover from 99999... */
buf[0] = '1'; /* later digits are 0 */
++*decpt;
if (f_flag)
++p_last;
break;
}
*p = '0';
} while (++*--p > '9'); /* propagate carries left */
*p_last = '\0';
}
return (buf);
}
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