110 lines
3.1 KiB
C
110 lines
3.1 KiB
C
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/* _WStoflt function */
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#include <locale.h>
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#include <wchar.h>
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#include <wctype.h>
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#include "xmath.h"
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_C_STD_BEGIN
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#if !defined(MRTDLL)
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_C_LIB_DECL
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#endif /* defined(MRTDLL) */
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#define BASE 10 /* decimal */
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#define NDIG 9 /* decimal digits per long element */
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#define MAXSIG (5 * NDIG) /* maximum significant digits to keep */
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_CRTIMP2_PURE int __CLRCALL_PURE_OR_CDECL _WStoflt(const wchar_t *s0, const wchar_t *s,
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wchar_t **endptr, long lo[], int maxsig)
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{ /* convert wide string to array of long plus exponent */
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char buf[MAXSIG + 1]; /* worst case, with room for rounding digit */
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int nsig; /* number of significant digits seen */
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int seen; /* any valid field characters seen */
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int word = 0; /* current long word to fill */
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maxsig *= NDIG; /* convert word count to digit count */
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if (MAXSIG < maxsig)
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maxsig = MAXSIG; /* protect against bad call */
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lo[0] = 0; /* power of ten exponent */
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lo[1] = 0; /* first NDIG-digit word of fraction */
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for (seen = 0; *s == L'0'; ++s, seen = 1)
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; /* strip leading zeros */
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for (nsig = 0; iswdigit(*s); ++s, seen = 1)
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if (nsig <= maxsig)
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buf[nsig++] = (char)(*s - L'0'); /* accumulate a digit */
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else
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++lo[0]; /* too many digits, just scale exponent */
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if (*s == btowc(localeconv()->decimal_point[0]))
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++s;
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if (nsig == 0)
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for (; *s == L'0'; ++s, seen = 1)
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--lo[0]; /* scale for stripped zeros after point */
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for (; iswdigit(*s); ++s, seen = 1)
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if (nsig <= maxsig)
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{ /* accumulate a fraction digit */
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buf[nsig++] = (char)(*s - L'0');
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--lo[0];
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}
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if (maxsig < nsig)
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{ /* discard excess digit after rounding up */
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unsigned int ms = maxsig; /* to quiet warnings */
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if (BASE / 2 <= buf[ms])
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++buf[ms - 1]; /* okay if digit becomes BASE */
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nsig = maxsig;
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++lo[0];
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}
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for (; 0 < nsig && buf[nsig - 1] == '\0'; --nsig)
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++lo[0]; /* discard trailing zeros */
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if (nsig == 0)
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buf[nsig++] = '\0'; /* ensure at least one digit */
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if (seen)
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{ /* convert digit sequence to words */
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int bufidx = 0; /* next digit in buffer */
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int wordidx = NDIG - nsig % NDIG; /* next digit in word (% NDIG) */
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word = wordidx % NDIG == 0 ? 0 : 1;
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for (; bufidx < nsig; ++wordidx, ++bufidx)
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if (wordidx % NDIG == 0)
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lo[++word] = buf[bufidx];
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else
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lo[word] = lo[word] * BASE + buf[bufidx];
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if (*s == L'e' || *s == L'E')
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{ /* parse exponent */
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const wchar_t *ssav = s;
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const wchar_t esign = *++s == L'+' || *s == L'-'
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? *s++ : L'+';
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int eseen = 0;
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long lexp = 0;
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for (; iswdigit(*s); ++s, eseen = 1)
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if (lexp < 100000000) /* else overflow */
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lexp = lexp * 10 + *s - L'0';
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if (esign == L'-')
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lexp = -lexp;
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lo[0] += lexp;
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if (!eseen)
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s = ssav; /* roll back if incomplete exponent */
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}
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}
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if (!seen)
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word = 0; /* return zero if bad parse */
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if (endptr)
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*endptr = (wchar_t *)(seen ? s : s0); /* roll back if bad parse */
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return (word);
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}
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#if !defined(MRTDLL)
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_END_C_LIB_DECL
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#endif /* !defined(MRTDLL) */
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_C_STD_END
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/*
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* Copyright (c) 1992-2012 by P.J. Plauger. ALL RIGHTS RESERVED.
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* Consult your license regarding permissions and restrictions.
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V6.00:0009 */
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