byte_diff.c

来自「It support IPv4 and IPv6 unicast and mul」· C语言 代码 · 共 17 行

#include "byte.h"

int byte_diff(register const void* S,register unsigned int n,
	      register const void* T)
{
  register const char *s=S;
  register const char *t=T;
  for (;;) {
    if (!n) return 0; if (*s != *t) break; ++s; ++t; --n;
    if (!n) return 0; if (*s != *t) break; ++s; ++t; --n;
    if (!n) return 0; if (*s != *t) break; ++s; ++t; --n;
    if (!n) return 0; if (*s != *t) break; ++s; ++t; --n;
  }
  return ((int)(unsigned int)(unsigned char) *s)
       - ((int)(unsigned int)(unsigned char) *t);
}