/* _WStoflt function */
#include <locale.h>
#include <wchar.h>
#include <wctype.h>
#include "xmath.h"

#define BASE	10	/* decimal */
#define NDIG	9	/* decimal digits per long element */
#define MAXSIG	(5 * NDIG)	/* maximum significant digits to keep */

int _WStoflt(const wchar_t *s0, const wchar_t *s,
	wchar_t **endptr, long lo[], int maxsig)
	{	/* convert wide string to array of long plus exponent */
	char buf[MAXSIG + 1];	/* worst case, with room for rounding digit */
	int nsig = 0;	/* number of significant digits seen */
	int seen = 0;	/* any valid field characters seen */
	int word = 0;	/* current long word to fill */

	maxsig *= NDIG;	/* convert word count to digit count */
	if (MAXSIG < maxsig)
		{
		maxsig = MAXSIG;	/* protect against bad call */
		}

	lo[0] = 0;	/* power of ten exponent */
	lo[1] = 0;	/* first NDIG-digit word of fraction */

	while (*s == L'0')
		{	/* strip leading zeros */
		++s;
		seen = 1;
		}

	while (iswdigit(*s))
		{
		if (nsig <= maxsig)
			{
			buf[nsig++] = (char)(*s - L'0');	/* accumulate a digit */
			}
		else
			{
			++lo[0];	/* too many digits, just scale exponent */
			}

		++s;
		seen = 1;
		}

	if (*s == btowc(localeconv()->decimal_point[0]))
		{
		++s;
		}

	if (nsig == 0)
		{
		while (*s == L'0')
			{
			--lo[0];	/* scale for stripped zeros after point */
			++s;
			seen = 1;
			}
		}

	while (iswdigit(*s))
		{
		if (nsig <= maxsig)
			{	/* accumulate a fraction digit */
			buf[nsig++] = (char)(*s - L'0');
			--lo[0];
			}

		++s;
		seen = 1;
		}

	if (maxsig < nsig)
		{	/* discard excess digit after rounding up */
		unsigned int ms = maxsig;	/* to quiet warnings */
		if (BASE / 2 <= buf[ms])
			{
			++buf[ms - 1];	/* okay if digit becomes BASE */
			}

		nsig = maxsig;
		++lo[0];
		}

	for (; 0 < nsig && buf[nsig - 1] == '\0'; --nsig)
		{
		++lo[0];	/* discard trailing zeros */
		}

	if (nsig == 0)
		{
		buf[nsig++] = '\0';	/* ensure at least one digit */
		}

	if (seen)
		{	/* convert digit sequence to words */
		int bufidx = 0;	/* next digit in buffer */
		int wordidx = NDIG - nsig % NDIG;	/* next digit in word (% NDIG) */

		word = wordidx % NDIG == 0 ? 0 : 1;
		for (; bufidx < nsig; ++wordidx, ++bufidx)
			{
			if (wordidx % NDIG == 0)
				{
				lo[++word] = buf[bufidx];
				}
			else
				{
				lo[word] = lo[word] * BASE + buf[bufidx];
				}
			}

		if (*s == L'e' || *s == L'E')
			{	/* parse exponent */
			const wchar_t *ssav = s;
			const wchar_t esign = *++s == L'+' || *s == L'-' ? *s++ : L'+';
			int eseen = 0;
			long lexp = 0;

			for (; iswdigit(*s); ++s, eseen = 1)
				{
				if (lexp < 100000000)	/* else overflow */
					{
					lexp = lexp * 10 + *s - L'0';
					}
				}

			if (esign == L'-')
				{
				lexp = -lexp;
				}

			lo[0] += lexp;
			if (!eseen)
				{
				s = ssav;	/* roll back if incomplete exponent */
				}
			}
		}

	if (!seen)
		{
		word = 0;	/* return zero if bad parse */
		}

	if (endptr)
		{
		*endptr = (wchar_t *)(seen ? s : s0);	/* roll back if bad parse */
		}

	return (word);
	}

/*
 * Copyright (c) by P.J. Plauger. All rights reserved.
 * Consult your license regarding permissions and restrictions.
V6.50:0009 */