memmove.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。

/*
 * $Id: memmove.c 26106 2007-03-15 10:58:19Z hpoussin $
 */

#include <string.h>


void * memmove(void *dest,const void *src,size_t count)
{
    char *char_dest = (char *)dest;
    char *char_src = (char *)src;

    if ((char_dest <= char_src) || (char_dest >= (char_src+count)))
    {
        /*  non-overlapping buffers */
        while(count > 0)
	{
            *char_dest = *char_src;
            char_dest++;
            char_src++;
            count--;
	}
    }
    else
    {
        /* overlaping buffers */
        char_dest = (char *)dest + count - 1;
        char_src = (char *)src + count - 1;

        while(count > 0)
	{
           *char_dest = *char_src;
           char_dest--;
           char_src--;
           count--;
	}
    }

    return dest;
}