NetBSD/lib/libc/hp300/stdlib/atof.c

151 lines
4.4 KiB
C

/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
/*static char sccsid[] = "from: @(#)atof.c 5.2 (Berkeley) 4/12/91";*/
static char rcsid[] = "$Id: atof.c,v 1.2 1993/08/01 18:41:45 mycroft Exp $";
#endif /* LIBC_SCCS and not lint */
/*
* simple atof() for IEEE 754 architectures
*/
#include <machine/endian.h>
#include <stdlib.h>
#include <math.h>
#include <ctype.h>
static double twoemax = 9007199254740992.; /*2^53*/
/* attempt to be as exact as possible */
static struct {
long low_word;
long high_word;
} exp5[] = {
#if BYTE_ORDER == BIG_ENDIAN
{ 0x40140000, 0x00000000 }, /* 5 */
{ 0x40390000, 0x00000000 }, /* 25 */
{ 0x40838800, 0x00000000 }, /* 625 */
{ 0x4117d784, 0x00000000 }, /* 390625 */
{ 0x4241c379, 0x37e08000 }, /* 152587890625 */
{ 0x4493b8b5, 0xb5056e17 }, /* 2.3283064365387e+022 */
{ 0x49384f03, 0xe93ff9f6 }, /* 5.42101086242753e+044 */
{ 0x52827748, 0xf9301d33 }, /* 2.93873587705572e+089 */
{ 0x65154fdd, 0x7f73bf3f } /* 8.63616855509445e+178 */
#else /* BYTE_ORDER == LITTLE_ENDIAN */
{ 0x00000000, 0x40140000 }, /* 5 */
{ 0x00000000, 0x40390000 }, /* 25 */
{ 0x00000000, 0x40838800 }, /* 625 */
{ 0x00000000, 0x4117d784 }, /* 390625 */
{ 0x37e08000, 0x4241c379 }, /* 152587890625 */
{ 0xb5056e17, 0x4493b8b5 }, /* 2.3283064365387e+022 */
{ 0xe93ff9f6, 0x49384f03 }, /* 5.42101086242753e+044 */
{ 0xf9301d33, 0x52827748 }, /* 2.93873587705572e+089 */
{ 0x7f73bf3f, 0x65154fdd } /* 8.63616855509445e+178 */
#endif
};
double
atof(p)
register const char *p;
{
register int c;
register int exp = 0;
register int eexp = 0;
double fl = 0;
double flexp = 1.0;
int bexp;
int neg = 1;
int negexp = 1;
while (isspace(*p))
++p;
if ((c = *p++) == '-')
neg = -1;
else if (c == '+')
/* skip it */;
else
--p;
while ((c = *p++) && isdigit(c))
if (fl < twoemax)
fl = 10 * fl + (c-'0');
else
++exp;
if (c == '.')
while ((c = *p++) && isdigit(c))
if (fl < twoemax) {
fl = 10 * fl + (c-'0');
--exp;
}
if (c == 'E' || c == 'e') {
if ((c = *p++) == '-')
negexp = -1;
else if (c == '+')
/* skip it */;
else
--p;
while ((c = *p++) && isdigit(c))
eexp = 10 * eexp + (c-'0');
if (negexp < 0)
eexp = -eexp;
exp += eexp;
}
bexp = exp;
if (exp < 0)
exp = -exp;
for (c = 0; exp && c < sizeof exp5 / sizeof exp5[0]; ++c) {
if (exp & 1)
flexp *= *(double *)&exp5[c];
exp >>= 1;
}
if (bexp < 0)
fl /= flexp;
else
fl *= flexp;
fl = ldexp(fl, bexp);
return neg < 0 ? -fl : fl;
}