mbsnbicm.c

C标准库源代码,能提高对C的理解,不错的哦

/***
*mbsnbicmp.c - Compare n bytes of strings, ignoring case (MBCS)
*
*       Copyright (c) 1985-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Compare n bytes of strings, ignoring case (MBCS)
*
*******************************************************************************/

#ifdef _MBCS

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

/***
* _mbsnbicmp - Compare n bytes of strings, ignoring case (MBCS)
*
*Purpose:
*       Compares up to n bytes of two strings for lexical order.
*       Strings are compared on a character basis, not a byte basis.
*       Case of characters is not considered.
*
*Entry:
*       unsigned char *s1, *s2 = strings to compare
*       size_t n = maximum number of bytes to compare
*
*Exit:
*       returns <0 if s1 < s2
*       returns  0 if s1 == s2
*       returns >0 if s1 > s2
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _mbsnbicmp(
        const unsigned char *s1,
        const unsigned char *s2,
        size_t n
        )
{
        unsigned short c1, c2;

        if (n==0)
                return(0);

        if ( _ISNOTMBCP )
            return _strnicmp(s1, s2, n);

        _mlock(_MB_CP_LOCK);

        while (n--) {

                c1 = *s1++;
                if (_ISLEADBYTE(c1)) {
                        if (n==0)
                {
                    c1 = 0; /* 'naked' lead - end of string */
                    c2 = _ISLEADBYTE(*s2) ? 0 : *s2;
                    goto test;
                }
                        if (*s1 == '\0')
                                c1 = 0;
                        else {
                                c1 = ((c1<<8) | *s1++);

                    if ( ((c1 >= _MBUPPERLOW1) && (c1 <= _MBUPPERHIGH1)) )
                        c1 += _MBCASEDIFF1;

                    else if ( ((c1 >= _MBUPPERLOW2) && (c1 <= _MBUPPERHIGH2)) )
                        c1 += _MBCASEDIFF2;
                        }
                }
                else
                c1 = _mbbtolower(c1);

                c2 = *s2++;
                if (_ISLEADBYTE(c2)) {
                        if (n==0)
                {
                    c2 = 0; /* 'naked' lead - end of string */
                    goto test;
                }
                n--;
                        if (*s2 == '\0')
                                c2 = 0;
                        else {
                                c2 = ((c2<<8) | *s2++);

                    if ( ((c2 >= _MBUPPERLOW1) && (c2 <= _MBUPPERHIGH1)) )
                        c2 += _MBCASEDIFF1;

                    else if ( ((c2 >= _MBUPPERLOW2) && (c2 <= _MBUPPERHIGH2)) )
                        c2 += _MBCASEDIFF2;
                        }
                }
                else
                c2 = _mbbtolower(c2);

test:
            if (c1 != c2)
            {
                _munlock(_MB_CP_LOCK);
                        return( (c1 > c2) ? 1 : -1);
            }

            if (c1 == 0)
            {
                _munlock(_MB_CP_LOCK);
                        return(0);
            }
        }

        _munlock(_MB_CP_LOCK);
        return(0);
}

#endif  /* _MBCS */