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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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Disc2.iso
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vc98
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crt
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src
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mbsnbcat.c
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1998-06-17
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/***
*mbsnbcat.c - concatenate string2 onto string1, max length n bytes
*
* Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines mbsnbcat() - concatenate maximum of n bytes
*
*******************************************************************************/
#ifdef _MBCS
#include <mtdll.h>
#include <cruntime.h>
#include <string.h>
#include <mbdata.h>
#include <mbctype.h>
#include <mbstring.h>
#define _MBSBTYPE(str,len) _mbsbtype(str,len)
/***
* _mbsnbcat - concatenate max cnt bytes onto dst
*
*Purpose:
* Concatenates src onto dst, with a maximum of cnt bytes copied.
* Handles 2-byte MBCS characters correctly.
*
*Entry:
* unsigned char *dst - string to concatenate onto
* unsigned char *src - string to concatenate from
* int cnt - number of bytes to copy
*
*Exit:
* returns dst, with src (at least part) concatenated on
*
*Exceptions:
*
*******************************************************************************/
unsigned char * __cdecl _mbsnbcat(
unsigned char *dst,
const unsigned char *src,
size_t cnt
)
{
unsigned char *start;
if (!cnt)
return(dst);
if ( _ISNOTMBCP )
return strncat(dst, src, cnt);
_mlock(_MB_CP_LOCK);
start = dst;
while (*dst++)
;
--dst; // dst now points to end of dst string
/* if last char in string is a lead byte, back up pointer */
if (_MBSBTYPE(start, (int) ((dst - start) - 1)) == _MBC_LEAD)
--dst;
/* copy over the characters */
while (cnt--) {
if (_ISLEADBYTE(*src)) {
*dst++ = *src++;
if (!cnt--) { /* write nul if cnt exhausted */
dst[-1] = '\0';
break;
}
if ((*dst++ = *src++)=='\0') { /* or if no trail byte */
dst[-2] = '\0';
break;
}
}
else if ((*dst++ = *src++) == '\0')
break;
}
/* enter final nul, if necessary */
if (_MBSBTYPE(start, (int) ((dst - start) - 1)) == _MBC_LEAD)
dst[-1] = '\0';
else
*dst = '\0';
_munlock(_MB_CP_LOCK);
return(start);
}
#endif /* _MBCS */