前文中，有一个叫 _nop_ 的函数，我不知道是干什么的，特意到QQ上问了问，一个哥们给了一段东西，原来叫“空指令”，作用就是占用一个CPU运算周期，呵呵，特意把原文贴上来，同时感谢那位朋友。
#include <intrins.h>
void _nop_ (void);
Description:
The _nop_ routine inserts an 8051 NOP instruction into the program. This routine can be used to pause for 1 CPU cycle. This routine is implemented as an intrinsic function. The code required is included in-line rather than being called.
Return Value:
None.
Attributes:
reentrant, intrinsic
See Also:
-
Example
#include <intrins.h>
#include <stdio.h> /* for printf */
void tst_nop (void) {
P1 = 0xFF;
_nop_ (); /* delay for hardware */
_nop_ ();
_nop_ ();
P1 = 0x00;
}