[UCRT] Import Microsoft.Windows.SDK.CRTSource version 10.0.22621.3

Imported from https://www.nuget.org/packages/Microsoft.Windows.SDK.CRTSource/10.0.22621.3
License: MIT

sdk/lib/ucrt/mbstring/mbsnccnt.cpp

@@ -0,0 +1,67 @@
+/***
+*mbsnccnt.c - Return char count of MBCS string
+*
+*       Copyright (c) Microsoft Corporation.  All rights reserved.
+*
+*Purpose:
+*       Return char count of MBCS string
+*
+*******************************************************************************/
+#ifndef _MBCS
+    #error This file should only be compiled with _MBCS defined
+#endif
+
+#include <corecrt_internal_mbstring.h>
+#include <locale.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:
+*       Input parameters are validated. Refer to the validation section of the function.
+*
+*******************************************************************************/
+
+extern "C" size_t __cdecl _mbsnccnt_l(
+        const unsigned char *string,
+        size_t bcnt,
+        _locale_t plocinfo
+        )
+{
+        size_t n;
+        _LocaleUpdate _loc_update(plocinfo);
+
+        _VALIDATE_RETURN(string != nullptr || bcnt == 0, EINVAL, 0);
+
+        for (n = 0; (bcnt-- && *string); n++, string++) {
+            if ( _ismbblead_l(*string, _loc_update.GetLocaleT()) ) {
+                if ( (!bcnt--) || (*++string == '\0'))
+                    break;
+            }
+        }
+
+        return(n);
+}
+extern "C" size_t (__cdecl _mbsnccnt)(
+        const unsigned char *string,
+        size_t bcnt
+        )
+{
+    return _mbsnccnt_l(string, bcnt, nullptr);
+}