Question

单片机C51中c语言函数（-nop-()）求助

今天在学习单片机c语言时，看到程序里有一个如此定义：
#define delayNOP() {_nop_();_nop_();_nop_();_nop_();};
我想问一下在单片机c语言中#include <intrins.h>头文件中所包含的
extern void _nop_ (void);
extern bit _testbit_ (bit);
extern unsigned char _chkfloat_(float);
这几个函数定义一般可以怎么用呢？

Answer 1

extern void _nop_ (void); //空操作，相当于8051的NOP指令
extern bit _testbit_ (bit); //测试并清零位，相当于8051的JBC指令
extern unsigned char _cror_ (unsigned char, unsigned char); //字符循环右移
extern unsigned int _iror_ (unsigned int, unsigned char); //整数循环右移
extern unsigned long _lror_ (unsigned long, unsigned char); //长整数循环右移
extern unsigned char _crol_ (unsigned char, unsigned char); //字符循环左移
extern unsigned int _irol_ (unsigned int, unsigned char); //整数循环左移
extern unsigned long _lrol_ (unsigned long, unsigned char); //长整数循环左移
extern unsigned char _chkfloat_(float); //测试并返回源点数状态
看你的要求~~