环形缓冲buffer之串口应用

前言

在单片机开发过程中，如串口通讯中，大家往往会遇到数据传输有时候并发量很大，处理不过来导致数据丢失。实际如何确保数据不丢失？估计有点经验的朋友都会想到缓冲存储。对的，先将数据存储起来，再慢慢对数据做处理。

1 环形缓冲队列

环形缓冲队列，如下图，再初始化时队列头尾相等，表示没有数据缓冲，当接收到一个数据时，队列头加1，并把这个数据存在移动到的位置下，实现数据保存。当头尾队列不相等时，尾队列指针追头队列移动，这时就可以将数据提取出来。

1.1程序 1.11队列实现

#include "sy_fifo.h"
#include 
#include 
#include 
//创建队列初始化
void sy_obj_fifo_create(obj_fifo_typ_t *pfifo)
{
	  pfifo->_head = 0;
	  pfifo->_tail = 0;
      pfifo->cmd_pos = 0;
	  pfifo->cmd_state = 0;
}
//队列数据压栈
unsigned int sy_obj_fifo_push(obj_fifo_typ_t *pfifo, const unsigned char data)
{
    unsigned int pos = 0;
	pos = (pfifo->_head+1)%QUEUE_MAX_SIZE;
    if (pfifo==NULL)
    {
        return 0;
    }
    if(pos!=pfifo->_tail)  //非满状态
    {
		 pfifo->_data[pfifo->_head] = data;
         pfifo->_head = pos;
		
		return 1;
    }
   return 0;
}
//数据占用大小
unsigned int sy_obj_fifo_get_occupy_size(obj_fifo_typ_t *pfifo)
{
    if (pfifo==NULL) return 0;
   return (((pfifo->_head+QUEUE_MAX_SIZE-pfifo->_tail)%QUEUE_MAX_SIZE)*CMD_MAX_SIZE);
}
//从队列中提取指定长度数据 ,这里只是提示一个例子，具体根据自己实际项目实现
unsigned int sy_obj_fifo_read(obj_fifo_typ_t *pfifo, unsigned char *buf,const unsigned int size)
{

	unsigned int i= 0;
	unsigned int data_len = 0;

    if ((size==0) || (pfifo==NULL) || (buf==NULL))
    {
	   return 0;
    }

	if(sy_obj_fifo_get_occupy_size(pfifo)<size) return 0; //数据长度不足，退出

  for(i= 0;i<size;i++){
  
    if( pfifo->_tail!= pfifo->_head)                                          //非空状态
    {
	
          *buf =  pfifo->_data[ pfifo->_tail];
		  buf++;
          pfifo->_tail = (pfifo->_tail+1)%QUEUE_MAX_SIZE;
          data_len++;
    }  
  }
    return data_len;
}

1.12 头文件实现

#ifndef __SY_FIFO_H
#define __SY_FIFO_H
#define QUEUE_MAX_SIZE 1000 
typedef struct
{
	unsigned int cmd_state;
	unsigned int cmd_pos;
    unsigned int _head;                                                       //队列头
    unsigned int _tail;                                                       //队列尾
    unsigned char _data[QUEUE_MAX_SIZE]; 
}obj_fifo_typ_t;
void sy_obj_fifo_create(obj_fifo_typ_t *pfifo);
unsigned int sy_obj_fifo_push(obj_fifo_typ_t *pfifo, const unsigned char data);
unsigned int sy_obj_fifo_read(obj_fifo_typ_t *pfifo, unsigned char *buf,const unsigned int size);
unsigned int sy_obj_fifo_get_occupy_size(obj_fifo_typ_t *pfifo);

#endif

1.13 demo

.......................................
obj_fifo_typ_t  obj_usart_buff; //定义一个实例
void main(void){
unsigned int data_size = 0;
unsigned  char buff[20] = {0};
..............//user handle
sy_obj_fifo_create(&obj_usart_buff); //创建一个环形队列实例
	while(1){
	data_size = sy_obj_fifo_read(&obj_usart_buff,buff,10);//取10个数据
	if(data_size == 10)
	// user handle
	}
}

//串口为例将串口接收到的数据压入队列中
void UART0_IRQHandler(void)
{
	unsigned char data = 0;
    if (UART_GetITIdentity(UART0) == UART_IT_RX)
    {
		 data = UART_ReceiveData(UART0);
		sy_obj_fifo_push(&obj_usart_buff, data); //将数据存到队列中
    }
    else if (UART_GetITIdentity(UART0) == UART_IT_TX)
    {
        UART_ClearTxITPendingBit(UART0);
    }
	
}