windows-nt/Source/XPSP1/NT/base/crts/crtw32/mbstring/mbsnbcnt.c
2020-09-26 16:20:57 +08:00

91 lines
2.2 KiB
C

/***
*mbsnbcnt.c - Returns byte count of MBCS string
*
* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Returns byte count of MBCS string
*
*Revision History:
* 11-19-92 KRS Ported from 16-bit sources.
* 10-05-93 GJF Replaced _CRTAPI1 with __cdecl.
* 04-15-93 CFW Add _MB_CP_LOCK.
* 05-19-94 CFW Enable non-Win32.
* 04-15-98 GJF Revised multithread support based on threadmbcinfo
* structs
*
*******************************************************************************/
#ifdef _MBCS
#include <mtdll.h>
#include <cruntime.h>
#include <mbdata.h>
#include <mbctype.h>
#include <mbstring.h>
/***
* _mbsnbcnt - Returns byte count of MBCS string
*
*Purpose:
* Returns the number of bytes between the start of the supplied
* string and the char count supplied. That is, this routine
* indicates how many bytes are in the first "ccnt" characters
* of the string.
*
*Entry:
* unsigned char *string = pointer to string
* unsigned int ccnt = number of characters to scan
*
*Exit:
* Returns number of bytes between string and ccnt.
*
* If the end of the string is encountered before ccnt chars were
* scanned, then the length of the string in bytes is returned.
*
*Exceptions:
*
*******************************************************************************/
size_t __cdecl _mbsnbcnt(
const unsigned char *string,
size_t ccnt
)
{
#ifdef _MT
pthreadmbcinfo ptmbci = _getptd()->ptmbcinfo;
if ( ptmbci != __ptmbcinfo )
ptmbci = __updatetmbcinfo();
return __mbsnbcnt_mt(ptmbci, string, ccnt);
}
size_t __cdecl __mbsnbcnt_mt(
pthreadmbcinfo ptmbci,
const unsigned char *string,
size_t ccnt
)
{
#endif
unsigned char *p;
for (p = (char *)string; (ccnt-- && *p); p++) {
#ifdef _MT
if ( __ismbblead_mt(ptmbci, *p) ) {
#else
if ( _ismbblead(*p) ) {
#endif
if (*++p == '\0') {
--p;
break;
}
}
}
return ((size_t) ((char *)p - (char *)string));
}
#endif /* _MBCS */