mbsnccnt.c

C标准库源代码

/***
*mbsnccnt.c - Return char count of MBCS string
*
*       Copyright (c) 1985-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Return char count of MBCS string
*
*******************************************************************************/

#ifdef _MBCS

#include <mtdll.h>
#include <cruntime.h>
#include <mbdata.h>
#include <mbctype.h>
#include <mbstring.h>


/***
* _mbsnccnt - Return char count of MBCS string
*
*Purpose:
*       Returns the number of chars between the start of the supplied
*       string and the byte count supplied.  That is, this routine
*       indicates how many chars are in the first "bcnt" bytes
*       of the string.
*
*Entry:
*       const unsigned char *string = pointer to string
*       unsigned int bcnt = number of bytes to scan
*
*Exit:
*       Returns number of chars between string and bcnt.
*
*       If the end of the string is encountered before bcnt chars were
*       scanned, then the length of the string in chars is returned.
*
*Exceptions:
*
*******************************************************************************/

size_t __cdecl _mbsnccnt(
    const unsigned char *string,
    size_t bcnt
    )
{
        unsigned int n;

        _mlock(_MB_CP_LOCK);

        for (n = 0; (bcnt-- && *string); n++, string++) {

                if (_ISLEADBYTE(*string)) {
                        if ( (!bcnt--) || (*++string == '\0'))
                                break;
                }
        }

        _munlock(_MB_CP_LOCK);
        return(n);
}
#endif  /* _MBCS */