mbschr.c

C标准库源代码

/***
* mbschr.c - Search MBCS string for character
*
*       Copyright (c) 1985-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Search MBCS string for a character
*
*******************************************************************************/

#ifdef _MBCS

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


/***
* _mbschr - Search MBCS string for character
*
*Purpose:
*       Search the given string for the specified character.
*       MBCS characters are handled correctly.
*
*Entry:
*       unsigned char *string = string to search
*       int c = character to search for
*
*Exit:
*       returns a pointer to the first occurence of the specified char
*       within the string.
*
*       returns NULL if the character is not found n the string.
*
*Exceptions:
*
*******************************************************************************/


unsigned char * __cdecl _mbschr(
        const unsigned char *string,
        unsigned int c
        )
{
        unsigned short cc;

        if ( _ISNOTMBCP )
            return strchr(string, c);

        _mlock(_MB_CP_LOCK);

        for (; (cc = *string); string++)
        {
            if (_ISLEADBYTE(cc))
            {
                if (*++string == '\0')
                {
                    _munlock(_MB_CP_LOCK);
                    return NULL;        /* error */
                }
                if ( c == (unsigned int)((cc << 8) | *string) ) /* DBCS match */
                {
                    _munlock(_MB_CP_LOCK);
                    return (unsigned char *)(string - 1);
                }
            }
            else if (c == (unsigned int)cc)
                break;  /* SBCS match */
        }

        _munlock(_MB_CP_LOCK);

        if (c == (unsigned int)cc)      /* check for SBCS match--handles NUL char */
            return (unsigned char *)(string);

        return NULL;
}

#endif  /* _MBCS */