strtod.c

KPIT GNU Tools is a set of GNU development tools for Renesas microcontrollers.

/*
FUNCTION
        <<strtod>>, <<strtof>>---string to double or float

INDEX
	strtod
INDEX
	_strtod_r
INDEX
	strtof

ANSI_SYNOPSIS
        #include <stdlib.h>
        double strtod(const char *<[str]>, char **<[tail]>);
        float strtof(const char *<[str]>, char **<[tail]>);

        double _strtod_r(void *<[reent]>, 
                         const char *<[str]>, char **<[tail]>);

TRAD_SYNOPSIS
        #include <stdlib.h>
        double strtod(<[str]>,<[tail]>)
        char *<[str]>;
        char **<[tail]>;

        float strtof(<[str]>,<[tail]>)
        char *<[str]>;
        char **<[tail]>;

        double _strtod_r(<[reent]>,<[str]>,<[tail]>)
	char *<[reent]>;
        char *<[str]>;
        char **<[tail]>;

DESCRIPTION
	The function <<strtod>> parses the character string <[str]>,
	producing a substring which can be converted to a double
	value.  The substring converted is the longest initial
	subsequence of <[str]>, beginning with the first
	non-whitespace character, that has the format:
	.[+|-]<[digits]>[.][<[digits]>][(e|E)[+|-]<[digits]>] 
	The substring contains no characters if <[str]> is empty, consists
	entirely of whitespace, or if the first non-whitespace
	character is something other than <<+>>, <<->>, <<.>>, or a
	digit. If the substring is empty, no conversion is done, and
	the value of <[str]> is stored in <<*<[tail]>>>.  Otherwise,
	the substring is converted, and a pointer to the final string
	(which will contain at least the terminating null character of
	<[str]>) is stored in <<*<[tail]>>>.  If you want no
	assignment to <<*<[tail]>>>, pass a null pointer as <[tail]>.
	<<strtof>> is identical to <<strtod>> except for its return type.

	This implementation returns the nearest machine number to the
	input decimal string.  Ties are broken by using the IEEE
	round-even rule.

	The alternate function <<_strtod_r>> is a reentrant version.
	The extra argument <[reent]> is a pointer to a reentrancy structure.

RETURNS
	<<strtod>> returns the converted substring value, if any.  If
	no conversion could be performed, 0 is returned.  If the
	correct value is out of the range of representable values,
	plus or minus <<HUGE_VAL>> is returned, and <<ERANGE>> is
	stored in errno. If the correct value would cause underflow, 0
	is returned and <<ERANGE>> is stored in errno.

Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
*/

/****************************************************************

The author of this software is David M. Gay.

Copyright (C) 1998-2001 by Lucent Technologies
All Rights Reserved

Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name of Lucent or any of its entities
not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.

****************************************************************/

/* Please send bug reports to David M. Gay (dmg at acm dot org,
 * with " at " changed at "@" and " dot " changed to ".").	*/

/* Original file gdtoa-strtod.c Modified 06-21-2006 by Jeff Johnston to work within newlib.  */

#include <_ansi.h>
#include <errno.h>
#include <string.h>
#include "mprec.h"
#include "gdtoa.h"
#include "gd_qnan.h"

/* #ifndef NO_FENV_H */
/* #include <fenv.h> */
/* #endif */

#ifdef USE_LOCALE
#include "locale.h"
#endif

#ifdef IEEE_Arith
#ifndef NO_IEEE_Scale
#define Avoid_Underflow
#undef tinytens
/* The factor of 2^53 in tinytens[4] helps us avoid setting the underflow */
/* flag unnecessarily.  It leads to a song and dance at the end of strtod. */
static _CONST double tinytens[] = { 1e-16, 1e-32, 1e-64, 1e-128,
		9007199254740992.e-256
		};
#endif
#endif

#ifdef Honor_FLT_ROUNDS
#define Rounding rounding
#undef Check_FLT_ROUNDS
#define Check_FLT_ROUNDS
#else
#define Rounding Flt_Rounds
#endif

#ifndef NO_HEX_FP

static void
_DEFUN (ULtod, (L, bits, exp, k),
	__ULong *L _AND
	__ULong *bits _AND
	Long exp _AND
	int k)
{
	switch(k & STRTOG_Retmask) {
	  case STRTOG_NoNumber:
	  case STRTOG_Zero:
		L[0] = L[1] = 0;
		break;

	  case STRTOG_Denormal:
		L[_1] = bits[0];
		L[_0] = bits[1];
		break;

	  case STRTOG_Normal:
	  case STRTOG_NaNbits:
		L[_1] = bits[0];
		L[_0] = (bits[1] & ~0x100000) | ((exp + 0x3ff + 52) << 20);
		break;

	  case STRTOG_Infinite:
		L[_0] = 0x7ff00000;
		L[_1] = 0;
		break;

	  case STRTOG_NaN:
		L[_0] = 0x7fffffff;
		L[_1] = (__ULong)-1;
	  }
	if (k & STRTOG_Neg)
		L[_0] |= 0x80000000L;
}
#endif /* !NO_HEX_FP */
 
#ifdef INFNAN_CHECK
static int
_DEFUN (match, (sp, t),
	_CONST char **sp _AND
	char *t)
{
	int c, d;
	_CONST char *s = *sp;

	while( (d = *t++) !=0) {
		if ((c = *++s) >= 'A' && c <= 'Z')
			c += 'a' - 'A';
		if (c != d)
			return 0;
		}
	*sp = s + 1;
	return 1;
}
#endif /* INFNAN_CHECK */


double
_DEFUN (_strtod_r, (ptr, s00, se),
	struct _reent *ptr _AND
	_CONST char *s00 _AND
	char **se)
{
#ifdef Avoid_Underflow
	int scale;
#endif
	int bb2, bb5, bbe, bd2, bd5, bbbits, bs2, c, decpt, dsign,
		 e, e1, esign, i, j, k, nd, nd0, nf, nz, nz0, sign;
	_CONST char *s, *s0, *s1;
	double aadj, aadj1, adj, rv, rv0;
	Long L;
	__ULong y, z;
	_Bigint *bb, *bb1, *bd, *bd0, *bs, *delta;
#ifdef SET_INEXACT
	int inexact, oldinexact;
#endif
#ifdef Honor_FLT_ROUNDS
	int rounding;
#endif

	delta = bs = bd = NULL;
	sign = nz0 = nz = decpt = 0;
	dval(rv) = 0.;
	for(s = s00;;s++) switch(*s) {
		case '-':
			sign = 1;
			/* no break */
		case '+':
			if (*++s)
				goto break2;
			/* no break */
		case 0:
			goto ret0;
		case '\t':
		case '\n':
		case '\v':
		case '\f':
		case '\r':
		case ' ':
			continue;
		default:
			goto break2;
		}
 break2:
	if (*s == '0') {
#ifndef NO_HEX_FP
		{
		static FPI fpi = { 53, 1-1023-53+1, 2046-1023-53+1, 1, SI };
		Long exp;
		__ULong bits[2];
		switch(s[1]) {
		  case 'x':
		  case 'X':
			{
#if defined(FE_DOWNWARD) && defined(FE_TONEAREST) && defined(FE_TOWARDZERO) && defined(FE_UPWARD)
			FPI fpi1 = fpi;
			switch(fegetround()) {
			  case FE_TOWARDZERO:	fpi1.rounding = 0; break;
			  case FE_UPWARD:	fpi1.rounding = 2; break;
			  case FE_DOWNWARD:	fpi1.rounding = 3;
			  }
#else
#define fpi1 fpi
#endif
			switch((i = gethex(ptr, &s, &fpi1, &exp, &bb, sign)) & STRTOG_Retmask) {
			  case STRTOG_NoNumber:
				s = s00;
				sign = 0;
			  case STRTOG_Zero:
				break;
			  default:
				if (bb) {
					copybits(bits, fpi.nbits, bb);
					Bfree(ptr,bb);
					}
				ULtod(((U*)&rv)->L, bits, exp, i);
			  }}
			goto ret;
		  }
		}
#endif
		nz0 = 1;
		while(*++s == '0') ;
		if (!*s)
			goto ret;
		}
	s0 = s;
	y = z = 0;
	for(nd = nf = 0; (c = *s) >= '0' && c <= '9'; nd++, s++)
		if (nd < 9)
			y = 10*y + c - '0';
		else if (nd < 16)
			z = 10*z + c - '0';
	nd0 = nd;
#ifdef USE_LOCALE
	if (c == *localeconv()->decimal_point)
#else
	if (c == '.')
#endif
		{
		decpt = 1;
		c = *++s;
		if (!nd) {
			for(; c == '0'; c = *++s)
				nz++;
			if (c > '0' && c <= '9') {
				s0 = s;
				nf += nz;
				nz = 0;
				goto have_dig;
				}
			goto dig_done;
			}
		for(; c >= '0' && c <= '9'; c = *++s) {
 have_dig:
			nz++;
			if (c -= '0') {
				nf += nz;
				for(i = 1; i < nz; i++)
					if (nd++ < 9)
						y *= 10;
					else if (nd <= DBL_DIG + 1)
						z *= 10;
				if (nd++ < 9)
					y = 10*y + c;
				else if (nd <= DBL_DIG + 1)
					z = 10*z + c;
				nz = 0;
				}
			}
		}
 dig_done:
	e = 0;
	if (c == 'e' || c == 'E') {
		if (!nd && !nz && !nz0) {
			goto ret0;
			}
		s00 = s;
		esign = 0;
		switch(c = *++s) {
			case '-':
				esign = 1;
			case '+':
				c = *++s;
			}
		if (c >= '0' && c <= '9') {
			while(c == '0')
				c = *++s;
			if (c > '0' && c <= '9') {
				L = c - '0';
				s1 = s;
				while((c = *++s) >= '0' && c <= '9')
					L = 10*L + c - '0';
				if (s - s1 > 8 || L > 19999)
					/* Avoid confusion from exponents
					 * so large that e might overflow.
					 */
					e = 19999; /* safe for 16 bit ints */
				else
					e = (int)L;
				if (esign)
					e = -e;
				}
			else
				e = 0;
			}
		else
			s = s00;
		}
	if (!nd) {
		if (!nz && !nz0) {
#ifdef INFNAN_CHECK
			/* Check for Nan and Infinity */
			__ULong bits[2];
			static FPI fpinan =	/* only 52 explicit bits */
				{ 52, 1-1023-53+1, 2046-1023-53+1, 1, SI };
			if (!decpt)
			 switch(c) {
			  case 'i':
			  case 'I':
				if (match(&s,"nf")) {
					--s;
					if (!match(&s,"inity"))
						++s;
					dword0(rv) = 0x7ff00000;
					dword1(rv) = 0;
					goto ret;
					}
				break;
			  case 'n':
			  case 'N':
				if (match(&s, "an")) {
#ifndef No_Hex_NaN
					if (*s == '(' /*)*/
					 && hexnan(&s, &fpinan, bits)
							== STRTOG_NaNbits) {
						dword0(rv) = 0x7ff00000 | bits[1];
						dword1(rv) = bits[0];
						}
					else {
#endif
						dword0(rv) = NAN_WORD0;
						dword1(rv) = NAN_WORD1;
#ifndef No_Hex_NaN
						}
#endif
					goto ret;
					}
			  }
#endif /* INFNAN_CHECK */
 ret0:
			s = s00;
			sign = 0;
			}
		goto ret;
		}
	e1 = e -= nf;

	/* Now we have nd0 digits, starting at s0, followed by a
	 * decimal point, followed by nd-nd0 digits.  The number we're
	 * after is the integer represented by those digits times
	 * 10**e */

	if (!nd0)
		nd0 = nd;
	k = nd < DBL_DIG + 1 ? nd : DBL_DIG + 1;
	dval(rv) = y;
	if (k > 9) {
#ifdef SET_INEXACT
		if (k > DBL_DIG)
			oldinexact = get_inexact();
#endif
		dval(rv) = tens[k - 9] * dval(rv) + z;
		}
	bd0 = 0;
	if (nd <= DBL_DIG
#ifndef RND_PRODQUOT
#ifndef Honor_FLT_ROUNDS
		&& Flt_Rounds == 1
#endif
#endif
			) {
		if (!e)
			goto ret;
		if (e > 0) {
			if (e <= Ten_pmax) {
#ifdef VAX
				goto vax_ovfl_check;
#else
#ifdef Honor_FLT_ROUNDS
				/* round correctly FLT_ROUNDS = 2 or 3 */
				if (sign) {
					rv = -rv;
					sign = 0;
					}
#endif
				/* rv = */ rounded_product(dval(rv), tens[e]);
				goto ret;
#endif
				}
			i = DBL_DIG - nd;
			if (e <= Ten_pmax + i) {
				/* A fancier test would sometimes let us do
				 * this for larger i values.
				 */
#ifdef Honor_FLT_ROUNDS
				/* round correctly FLT_ROUNDS = 2 or 3 */
				if (sign) {
					rv = -rv;
					sign = 0;
					}
#endif
				e -= i;
				dval(rv) *= tens[i];
#ifdef VAX
				/* VAX exponent range is so narrow we must
				 * worry about overflow here...
				 */
 vax_ovfl_check:
				dword0(rv) -= P*Exp_msk1;
				/* rv = */ rounded_product(dval(rv), tens[e]);
				if ((dword0(rv) & Exp_mask)
				 > Exp_msk1*(DBL_MAX_EXP+Bias-1-P))
					goto ovfl;
				dword0(rv) += P*Exp_msk1;
#else
				/* rv = */ rounded_product(dval(rv), tens[e]);
#endif
				goto ret;
				}
			}
#ifndef Inaccurate_Divide
		else if (e >= -Ten_pmax) {
#ifdef Honor_FLT_ROUNDS
			/* round correctly FLT_ROUNDS = 2 or 3 */
			if (sign) {
				rv = -rv;
				sign = 0;
				}
#endif
			/* rv = */ rounded_quotient(dval(rv), tens[-e]);
			goto ret;
			}
#endif
		}
	e1 += nd - k;

#ifdef IEEE_Arith
#ifdef SET_INEXACT
	inexact = 1;
	if (k <= DBL_DIG)
		oldinexact = get_inexact();
#endif
#ifdef Avoid_Underflow
	scale = 0;
#endif
#ifdef Honor_FLT_ROUNDS
	if ((rounding = Flt_Rounds) >= 2) {
		if (sign)
			rounding = rounding == 2 ? 0 : 2;
		else
			if (rounding != 2)
				rounding = 0;
		}
#endif
#endif /*IEEE_Arith*/

	/* Get starting approximation = rv * 10**e1 */

	if (e1 > 0) {
		if ( (i = e1 & 15) !=0)
			dval(rv) *= tens[i];
		if (e1 &= ~15) {
			if (e1 > DBL_MAX_10_EXP) {
 ovfl:
#ifndef NO_ERRNO
				ptr->_errno = ERANGE;
#endif
				/* Can't trust HUGE_VAL */
#ifdef IEEE_Arith
#ifdef Honor_FLT_ROUNDS
				switch(rounding) {
				  case 0: /* toward 0 */
				  case 3: /* toward -infinity */
					dword0(rv) = Big0;
#ifndef _DOUBLE_IS_32BITS
					dword1(rv) = Big1;
#endif /*!_DOUBLE_IS_32BITS*/
					break;
				  default:
					dword0(rv) = Exp_mask;
#ifndef _DOUBLE_IS_32BITS
					dword1(rv) = 0;
#endif /*!_DOUBLE_IS_32BITS*/
				  }
#else /*Honor_FLT_ROUNDS*/
				dword0(rv) = Exp_mask;
#ifndef _DOUBLE_IS_32BITS
				dword1(rv) = 0;
#endif /*!_DOUBLE_IS_32BITS*/
#endif /*Honor_FLT_ROUNDS*/
#ifdef SET_INEXACT
				/* set overflow bit */
				dval(rv0) = 1e300;
				dval(rv0) *= dval(rv0);
#endif
#else /*IEEE_Arith*/
				dword0(rv) = Big0;
#ifndef _DOUBLE_IS_32BITS
				dword1(rv) = Big1;
#endif /*!_DOUBLE_IS_32BITS*/
#endif /*IEEE_Arith*/
				if (bd0)
					goto retfree;
				goto ret;
				}
			e1 >>= 4;
			for(j = 0; e1 > 1; j++, e1 >>= 1)
				if (e1 & 1)
					dval(rv) *= bigtens[j];
		/* The last multiplication could overflow. */
			dword0(rv) -= P*Exp_msk1;
			dval(rv) *= bigtens[j];