【Keil5 C51】AT89C52 做流水灯实验(调用C51的库函数_crol_)

_crol_ 函数的介绍

Cx51 User’s Guide

Summary

#include

unsigned char _crol_ (

  unsigned char c,        /* character to rotate left */

  unsigned char b);       /* bit positions to rotate */

Description

The _crol_ routine rotates the bit pattern for the character c left b bits. This routine is implemented as an intrinsic function （从c变量中的第1开始位 一次向左移动b位, 比如b = 1 时这串数字会这样移动：1111110–>11111101）

Return Value

The crol routine returns the rotated value of c.（把移动之后的值返回给c）

Example

#include

void test_crol (void) {

  char a;

  char b;

  a = 0xA5;

  b = _crol_(a,3); /* b now is 0x2D */

}

流水灯代码

使用AT89C52芯片，晶振为11.0592MHz

#include

#include

#define uint unsigned int

#define uchar unsigned char

void delay(uint time);  

void main()

{

uint led = 0xfe; //11111110 

while(1){

P1 = led; //11111110 先让P1口的第一个灯亮

delay(500); //延时0.5s

led = _crol_(led,1); //调用_crol_函数，使led的变量从第一个开始左移 11111110-->11111101

//再返回给led ，此时led = 11111101

}

}

void delay(uint time)  //delay = 1 ms 0.001s

{

uint x;

uint y;

uint z;

for(z = time; z > 0; z--){

for(x = 1; x > 0; x--){

for(y = 115; y > 0; y--){}

}

}

}

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