mbsncmp.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

/*
 * COPYRIGHT:   See COPYING in the top level directory
 * PROJECT:     ReactOS system libraries
 * FILE:        lib/msvcrt/mbstring/mbsncmp.c
 * PURPOSE:     Compares two strings to a maximum of n bytes or characters
 * PROGRAMER:   Ariadne
 * UPDATE HISTORY:
 *              12/04/99: Created
 */

#include <mbstring.h>

/*
 * @implemented
 */
int _mbsncmp(const unsigned char *str1, const unsigned char *str2, size_t n)
{
	unsigned char *s1 = (unsigned char *)str1;
	unsigned char *s2 = (unsigned char *)str2;

	unsigned short *short_s1, *short_s2;

	int l1, l2;

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

		if (*s1 == 0)
			break;

		l1 = _ismbblead(*s1);
		l2 = _ismbblead(*s2);
		if ( !l1 &&  !l2  ) {

			if (*s1 != *s2)
				return *s1 - *s2;
			else {
				s1 += 1;
				s2 += 1;
				n--;
			}
		}
		else if ( l1 && l2 ){
			short_s1 = (unsigned short *)s1;
			short_s2 = (unsigned short *)s2;
			if ( *short_s1 != *short_s2 )
				return *short_s1 - *short_s2;
			else {
				s1 += 2;
				s2 += 2;
				n--;

			}
		}
		else
			return *s1 - *s2;
	} while (n > 0);
	return 0;
}

/*
 * @implemented
 */
int _mbsnbcmp(const unsigned char *str1, const unsigned char *str2, size_t n)
{
	unsigned char *s1 = (unsigned char *)str1;
	unsigned char *s2 = (unsigned char *)str2;

	unsigned short *short_s1, *short_s2;

	int l1, l2;

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

		if (*s1 == 0)
			break;

		l1 = _ismbblead(*s1);
		l2 = _ismbblead(*s2);
		if ( !l1 &&  !l2  ) {

			if (*s1 != *s2)
				return *s1 - *s2;
			else {
				s1 += 1;
				s2 += 1;
				n--;
			}
		}
		else if ( l1 && l2 ){
			short_s1 = (unsigned short *)s1;
			short_s2 = (unsigned short *)s2;
			if ( *short_s1 != *short_s2 )
				return *short_s1 - *short_s2;
			else {
				s1 += 2;
				s2 += 2;
				n-=2;

			}
		}
		else
			return *s1 - *s2;
	} while (n > 0);
	return 0;
}