mbsrev.c

C标准库源代码

/***
*mbsrev.c - Reverse a string in place (MBCS)
*
*       Copyright (c) 1985-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Reverse a string in place (MBCS)
*
*******************************************************************************/

#ifdef _MBCS

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


/***
* _mbsrev - Reverse a string in place (MBCS)
*
*Purpose:
*       Reverses the order of characters in the string.  The terminating
*       null character remains in place.  The order of MBCS characters
*       is not changed.
*
*Entry:
*       unsigned char *string = string to reverse
*
*Exit:
*       returns string - now with reversed characters
*
*Exceptions:
*
*******************************************************************************/

unsigned char * __cdecl _mbsrev(
        unsigned char *string
        )
{

        unsigned char *start = string;
        unsigned char *left  = string;
        unsigned char c;

        if ( _ISNOTMBCP )
                return _strrev(string);

        _mlock(_MB_CP_LOCK);

        /* first go through and reverse the bytes in MBCS chars */
        while ( *string ) {

                if ( _ISLEADBYTE(*string++) ) {
                        if ( *string ) {
                                c = *string;
                                *string = *(string - 1);
                                *(string - 1) = c;
                                string++;
                        }
                        else /* second byte is EOS */
                                break;
                }
        }

        /* now reverse the whole string */
        string--;
        while ( left < string ) {
                c = *left;
                *left++ = *string;
                *string-- = c;
        }

        _munlock(_MB_CP_LOCK);
        return ( start );
}

#endif  /* _MBCS */