前言
在單片機開發過程中，如串口通訊中，大家往往會遇到數據傳輸有時候并發量很大，處理不過來導致數據丟失。實際如何確保數據不丟失？估計有點經驗的朋友都會想到緩沖存儲。對的，先將數據存儲起來，再慢慢對數據做處理。
1 環形緩沖隊列
環形緩沖隊列，如下圖，再初始化時隊列頭尾相等，表示沒有數據緩沖，當接收到一個數據時，隊列頭加1，并把這個數據存在移動到的位置下，實現數據保存。當頭尾隊列不相等時，尾隊列指針追頭隊列移動，這時就可以將數據提取出來。
1.1程序
1.11隊列實現
#include "sy_fifo.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//創建隊列初始化
void sy_obj_fifo_create(obj_fifo_typ_t *pfifo)
{
pfifo->_head = 0;
pfifo->_tail = 0;
pfifo->cmd_pos = 0;
pfifo->cmd_state = 0;
}
//隊列數據壓棧
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) //非滿狀態
{
pfifo->_data[pfifo->_head] = data;
pfifo->_head = pos;
return 1;
}
return 0;
}
//數據占用大小
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);
}
//從隊列中提取指定長度數據 ,這里只是提示一個例子，具體根據自己實際項目實現
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; //數據長度不足，退出
for(i= 0;i<size;i++){
if( pfifo->_tail!= pfifo->_head) //非空狀態
{
*buf = pfifo->_data[ pfifo->_tail];
buf++;
pfifo->_tail = (pfifo->_tail+1)%QUEUE_MAX_SIZE;
data_len++;
}
}
return data_len;
}
1.12 頭文件實現
#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; //隊列頭
unsigned int _tail; //隊列尾
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; //定義一個實例
void main(void){
unsigned int data_size = 0;
unsigned char buff[20] = {0};
..............//user handle
sy_obj_fifo_create(&obj_usart_buff); //創建一個環形隊列實例
while(1){
data_size = sy_obj_fifo_read(&obj_usart_buff,buff,10);//取10個數據
if(data_size == 10)
// user handle
}
}
//串口為例將串口接收到的數據壓入隊列中
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); //將數據存到隊列中
}
else if (UART_GetITIdentity(UART0) == UART_IT_TX)
{
UART_ClearTxITPendingBit(UART0);
}
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