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前言4 [+ n" v3 W0 a
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。
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1 环形缓冲队列
5 i4 b7 x% X' y% u6 n9 c' F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。
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1.1程序; {& ^8 }. S- t; v, S( N
1.11队列实现8 Q6 {: M: ^& A. d+ s: x' ~, Y
#include "sy_fifo.h"; ~, f; b) M, x0 L2 o8 B0 F
#include <stdio.h>
% F6 b' D$ ?* q#include <stdlib.h>
4 f7 Z) L: r/ I4 e$ f4 C1 M#include <string.h>
0 R0 S% D3 a; ]$ [//创建队列初始化2 R- O7 H* O, {) E+ p
void sy_obj_fifo_create(obj_fifo_typ_t *pfifo)
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pfifo->_head = 0;1 _' f/ j7 H0 h+ ?
pfifo->_tail = 0;6 f7 A$ F, e: L+ L' l: p; i- W
pfifo->cmd_pos = 0;4 z# g; p3 Y; ?# F5 S+ }! N+ |; H
pfifo->cmd_state = 0;8 V# B# y0 V1 ]& n3 S! j2 O5 o- _; {
}
5 B! [ B1 q" G' x' g//队列数据压栈
; d# ]# G- {9 R: Punsigned int sy_obj_fifo_push(obj_fifo_typ_t *pfifo, const unsigned char data)
1 ^( `9 k2 N# @- ] G" Y{
: y1 W4 Q4 T9 n5 Q# V& a unsigned int pos = 0;7 G8 Z% Q/ g) [4 E
pos = (pfifo->_head+1)%QUEUE_MAX_SIZE;
. }% Y+ v1 @8 U; R; Y, t7 C" U1 R" G1 Z if (pfifo==NULL)
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. K/ {5 |: S8 d+ \( H% b return 0;9 C6 I" k9 ~- T$ t8 W/ [, A
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if(pos!=pfifo->_tail) //非满状态 }% I/ V7 l# J$ X0 f
{
+ ~: ^3 `# _2 n2 C2 u, B pfifo->_data[pfifo->_head] = data;
. Q3 [% O; n/ J& J pfifo->_head = pos;
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$ v0 `0 W# w$ ~+ ?& ` return 1;
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return 0;* k* S+ q: `9 V; c. F
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//数据占用大小5 D6 \; o$ V3 V0 G2 d
unsigned int sy_obj_fifo_get_occupy_size(obj_fifo_typ_t *pfifo)6 C: ?5 @, w/ y( ]$ J& a8 o! W* t2 E
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if (pfifo==NULL) return 0;
0 @, V- i$ O9 M& g3 {3 G' ?. _ return (((pfifo->_head+QUEUE_MAX_SIZE-pfifo->_tail)%QUEUE_MAX_SIZE)*CMD_MAX_SIZE);+ _: q- {2 Z6 `! M$ Y5 c) ~
}
! h, q, e. k' _6 j) a% c8 m7 A//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0 C. M; U: a7 O. ]6 r3 i3 V+ j
unsigned int sy_obj_fifo_read(obj_fifo_typ_t *pfifo, unsigned char *buf,const unsigned int size)
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3 L' n D; ?5 `1 o& ^ unsigned int i= 0;
+ B/ F) Z4 u# \1 H- Z6 X0 c0 q unsigned int data_len = 0;: }' @* J2 q. b, |
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if ((size==0) || (pfifo==NULL) || (buf==NULL))" m+ v* @" d8 m. E( Q! o" i
{
; q3 L$ ]$ h; h/ e J+ \* i return 0;
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/ z, b4 {, V( A+ U% }4 h7 X$ m. h if(sy_obj_fifo_get_occupy_size(pfifo)<size) return 0; //数据长度不足,退出& A! U% x, ?0 L3 d8 K% D0 C) W
+ W8 _4 ?1 r- D8 U b% J for(i= 0;i<size;i++){
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; H2 O' o! P5 @" z X% a if( pfifo->_tail!= pfifo->_head) //非空状态
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*buf = pfifo->_data[ pfifo->_tail];
5 J1 X7 T% }; Q; i buf++;" Q. M/ I7 g2 z1 h: A
pfifo->_tail = (pfifo->_tail+1)%QUEUE_MAX_SIZE; U/ q' I1 X* Y1 K5 n8 n
data_len++;0 r; q% y0 v" v* `$ q0 H
} ' }( X7 G0 Z8 I" t5 S4 `
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return data_len;, q- @3 x( k! R2 k% n. q5 n5 I
}
' C! E) o! ~- B4 u6 u1.12 头文件实现
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#ifndef __SY_FIFO_H5 _$ K* Y6 C4 K w
#define __SY_FIFO_H
6 _" C0 q& z2 S! p#define QUEUE_MAX_SIZE 1000# U6 G) O) S, w! L3 I
typedef struct
5 S* l% u1 O3 e/ K4 P+ Z" q+ Q{
( Z) r% M6 [6 T unsigned int cmd_state;, f% u1 m2 ]: ]2 b2 n2 K
unsigned int cmd_pos;
6 V1 H9 K+ G! A unsigned int _head; //队列头: {. K! X/ D) b* r9 ]) w
unsigned int _tail; //队列尾
) ` A" d1 U A! \, g h unsigned char _data[QUEUE_MAX_SIZE];
z$ W# d- ?" B) w}obj_fifo_typ_t;( C7 s4 A! ?* H0 P! s& j
void sy_obj_fifo_create(obj_fifo_typ_t *pfifo);/ ~2 o% _0 F3 }. _( C/ r/ B
unsigned int sy_obj_fifo_push(obj_fifo_typ_t *pfifo, const unsigned char data);7 F4 C, F& H) ?8 z1 M- J& ?# o6 m
unsigned int sy_obj_fifo_read(obj_fifo_typ_t *pfifo, unsigned char *buf,const unsigned int size);# `) ]/ F8 t# n% @# g
unsigned int sy_obj_fifo_get_occupy_size(obj_fifo_typ_t *pfifo);
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#endif5 D) l: r* q& b, G. y
1.13 demo
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" ~2 X* U, W8 [6 a( Z; e7 S2 E( E, ^obj_fifo_typ_t obj_usart_buff; //定义一个实例) V, E5 a5 b) ]' z1 c& n5 I
void main(void){
$ u }% Q* u! i$ j2 y ~unsigned int data_size = 0;
. K' s" q' {; U: ~' lunsigned char buff[20] = {0};. t1 h0 g. I' s; _4 _) z" u
..............//user handle% C! O& |& k: o$ z; ]: m# V
sy_obj_fifo_create(&obj_usart_buff); //创建一个环形队列实例
4 {4 K6 `; E& l( R* Y c while(1){
8 [8 |% p3 S( M2 J/ _& q/ {% _, B3 t. B data_size = sy_obj_fifo_read(&obj_usart_buff,buff,10);//取10个数据. \+ |/ @8 F4 s; g8 q7 F, A
if(data_size == 10)
( O; O: z; v$ i // user handle
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9 b4 N( u l( A* O5 ~9 J//串口为例将串口接收到的数据压入队列中0 [7 D' Y- H4 ]; i
void UART0_IRQHandler(void)
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5 G! A6 W# j+ _! D7 E$ X5 w unsigned char data = 0;
8 W8 V+ a% D& @7 \5 C if (UART_GetITIdentity(UART0) == UART_IT_RX); ^; X( w5 |! ?. X2 c
{
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sy_obj_fifo_push(&obj_usart_buff, data); //将数据存到队列中% l8 M+ ]+ v+ z; n/ g: F( X; K
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else if (UART_GetITIdentity(UART0) == UART_IT_TX)6 w& H" }; e- `) W, a
{( `) w' ?0 D* Y& D U% X, s3 }; ~
UART_ClearTxITPendingBit(UART0);
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