windows-nt/Source/XPSP1/NT/base/crts/crtw32/convert/wcstoq.c

/***
*wcstoq.c - Contains C runtimes wcstoi64 and wcstoui64
*
*	Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
*	wcstoi64 - convert ascii string to signed __int64 integer
*	wcstoui64- convert ascii string to unsigned __int64 integer
*
*Revision History:
*   02-11-00  GB    Module created, based on strtoq.c
*   06-02-00  GB    Fixed the bug for IA64_MIN value.
*   08-01-00  GB    Added multilangual support
*
*******************************************************************************/

#include <cruntime.h>
#include <stdlib.h>
#include <limits.h>
#include <errno.h>
#include <ctype.h>
#include <mtdll.h>

int _wchartodigit(wchar_t ch);

/***
*wcstoq, wcstouq(nptr,endptr,ibase) - Convert ascii string to un/signed	__int64.
*
*Purpose:
*	Convert an ascii string to a 64-bit __int64 value.  The base
*	used for the caculations is supplied by the caller.  The base
*	must be in the range 0, 2-36.  If a base of 0 is supplied, the
*	ascii string must be examined to determine the base of the
*	number:
*		(a) First wchar_t = '0', second wchar_t = 'x' or 'X',
*		    use base 16.
*		(b) First wchar_t = '0', use base 8
*		(c) First wchar_t in range '1' - '9', use base 10.
*
*	If the 'endptr' value is non-NULL, then wcstoq/wcstouq places
*	a pointer to the terminating character in this value.
*	See ANSI standard for details
*
*Entry:
*	nptr == NEAR/FAR pointer to the start of string.
*	endptr == NEAR/FAR pointer to the end of the string.
*	ibase == integer base to use for the calculations.
*
*	string format: [whitespace] [sign] [0] [x] [digits/letters]
*
*Exit:
*	Good return:
*		result
*
*	Overflow return:
*		wcstoq -- _I64_MAX or _I64_MIN
*		wcstouq -- _UI64_MAX
*		wcstoq/wcstouq -- errno == ERANGE
*
*	No digits or bad base return:
*		0
*		endptr = nptr*
*
*Exceptions:
*	None.
*******************************************************************************/

/* flag values */
#define FL_UNSIGNED   1       /* wcstouq called */
#define FL_NEG	      2       /* negative sign found */
#define FL_OVERFLOW   4       /* overflow occured */
#define FL_READDIGIT  8       /* we've read at least one correct digit */

static unsigned __int64 __cdecl wcstoxq (
	const wchar_t *nptr,
	const wchar_t **endptr,
	int ibase,
	int flags
	)
{
	const wchar_t *p;
	wchar_t c;
	unsigned __int64 number;
	unsigned digval;
	unsigned __int64 maxval;
#ifdef  _MT
        pthreadlocinfo ptloci = _getptd()->ptlocinfo;

        if ( ptloci != __ptlocinfo )
            ptloci = __updatetlocinfo();
#endif

	p = nptr;			/* p is our scanning pointer */
	number = 0;			/* start with zero */

	c = *p++;			/* read wchar_t */
#ifdef  _MT
    while ( __iswspace_mt(ptloci, c) )
#else
    while ( iswspace(c) )
#endif
		c = *p++;		/* skip whitespace */

	if (c == '-') {
		flags |= FL_NEG;	/* remember minus sign */
		c = *p++;
	}
	else if (c == '+')
		c = *p++;		/* skip sign */

	if (ibase < 0 || ibase == 1 || ibase > 36) {
		/* bad base! */
		if (endptr)
			/* store beginning of string in endptr */
			*endptr = nptr;
		return 0L;		/* return 0 */
	}
	else if (ibase == 0) {
		/* determine base free-lance, based on first two chars of
		   string */
		if (_wchartodigit(c) != 0)
			ibase = 10;
		else if (*p == 'x' || *p == 'X')
			ibase = 16;
		else
			ibase = 8;
	}

	if (ibase == 16) {
		/* we might have 0x in front of number; remove if there */
	if (_wchartodigit(c) == 0 && (*p == L'x' || *p == L'X')) {
			++p;
			c = *p++;	/* advance past prefix */
		}
	}

	/* if our number exceeds this, we will overflow on multiply */
	maxval = _UI64_MAX / ibase;


	for (;;) {	/* exit in middle of loop */
		/* convert c to value */
		if ( (digval = _wchartodigit(c)) != -1 )
 			;
		else if ( __ascii_iswalpha(c) )
			digval = toupper(c) - 'A' + 10;
		else
			break;
		if (digval >= (unsigned)ibase)
			break;		/* exit loop if bad digit found */

		/* record the fact we have read one digit */
		flags |= FL_READDIGIT;

		/* we now need to compute number = number * base + digval,
		   but we need to know if overflow occured.  This requires
		   a tricky pre-check. */

		if (number < maxval || (number == maxval &&
		(unsigned __int64)digval <= _UI64_MAX % ibase)) {
			/* we won't overflow, go ahead and multiply */
			number = number * ibase + digval;
		}
		else {
			/* we would have overflowed -- set the overflow flag */
			flags |= FL_OVERFLOW;
		}

		c = *p++;		/* read next digit */
	}

	--p;				/* point to place that stopped scan */

	if (!(flags & FL_READDIGIT)) {
		/* no number there; return 0 and point to beginning of
		   string */
		if (endptr)
			/* store beginning of string in endptr later on */
			p = nptr;
		number = 0L;		/* return 0 */
	}
    else if ( (flags & FL_OVERFLOW) ||
              ( !(flags & FL_UNSIGNED) &&
                ( ( (flags & FL_NEG) && (number > -_I64_MIN) ) ||
                  ( !(flags & FL_NEG) && (number > _I64_MAX) ) ) ) )
    {
        /* overflow or signed overflow occurred */
        errno = ERANGE;
        if ( flags & FL_UNSIGNED )
            number = _UI64_MAX;
        else if ( flags & FL_NEG )
            number = (_I64_MIN);
        else
            number = _I64_MAX;
    }

	if (endptr != NULL)
		/* store pointer to wchar_t that stopped the scan */
		*endptr = p;

	if (flags & FL_NEG)
		/* negate result if there was a neg sign */
		number = (unsigned __int64)(-(__int64)number);

	return number;			/* done. */
}


__int64 _CRTIMP __cdecl _wcstoi64(
    const wchar_t *nptr,
    wchar_t **endptr,
    int ibase
    )
{
    return (__int64) wcstoxq(nptr, endptr, ibase, 0);
}
unsigned __int64 _CRTIMP __cdecl _wcstoui64 (
	const wchar_t *nptr,
	wchar_t **endptr,
	int ibase
	)
{
	return wcstoxq(nptr, endptr, ibase, FL_UNSIGNED);
}