stm32实用循环buffer

只看该作者 · 2021-12-31 23:34

笔者在实际开发中多次用到串口的循环buffer,最开始在网上搜索了相关**和资料，感觉通用性不是很高。自己也写过fifo,感觉还是过于臃肿。一直想找个完美的循环buffer。在看linux内核代码时，发现内核里面也经常使用fifo。linux内核代码是最优美、精简的，高效的代码。真是“山穷水尽疑无路，柳暗花明又一村”。特意移植除出来，希望对大家有用。代码设计的相当的巧妙~~~

头文件：

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/*******************************************************************************

* [url=home.php?mod=space&uid=288409]@file[/url]           : fifo.h

* [url=home.php?mod=space&uid=187600]@author[/url]   : cqx

* [url=home.php?mod=space&uid=895143]@version[/url]  : V0.0.1

* [url=home.php?mod=space&uid=212281]@date[/url]           : 29-november-2016

* @Brief          : This file provides all the fifo functions.

********************************************************************************

* @Attention:

* Non

*

*******************************************************************************/

 

/* Define to prevent recursive inclusion -------------------------------------*/

#ifndef _FIFO_H

#define _FIFO_H

 

#include <stm32f10x.h>

 

#ifdef __cplusplus

 extern "C" {

#endif

         

/* Includes ------------------------------------------------------------------*/

/* Define --------------------------------------------------------------------*/

#ifndef min

#define min(a, b) (((a) < (b)) ? (a) : (b))

#endif                

 

#define is_power_of_2(x)        ((x) != 0 && (((x) & ((x) - 1)) == 0))

                

/* Private typedef -----------------------------------------------------------*/

struct fifo {

        unsigned int        in;

        unsigned int        out;

        unsigned int        mask;

        unsigned char *data;

}; 

 

/* Function prototypes -------------------------------------------------------*/

extern unsigned int fifo_used(struct fifo *fifo);

extern signed int fifo_alloc(struct fifo *fifo, unsigned int size);

extern void         fifo_free(struct fifo *fifo);

extern int          fifo_init(struct fifo *fifo, unsigned char *buffer,        unsigned int size);

extern unsigned int fifo_in(struct fifo *fifo, unsigned char *buf, unsigned int len);

extern unsigned int fifo_out(struct fifo *fifo,        unsigned char *buf, unsigned int len);

         

#ifdef __cplusplus

}

#endif

 

#endif

只看该作者 · 2021-12-31 23:37

源文件：

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/******************************************************************************

* @File           : ringbuffer.c

* @Author   : cqx

* @Version  : V0.0.1

* @Date           : 29-november-2016

* @Brief          : This file provides all the fifo functions.

******************************************************************************

* @Attention:

* 

*

******************************************************************************/

/* Includes -----------------------------------------------------------------*/

#include "fifo.h"

#include "stdlib.h"

#include "string.h"

#include "includes.h"

 

/* Variables -----------------------------------------------------------------*/

/* Private functions ---------------------------------------------------------*/

/******************************************************************************/

 

/*

 * internal helper to calculate the unused elements in a fifo

 */

static __inline unsigned int fifo_unused(struct fifo *fifo)

{

  return (fifo->mask + 1) - (fifo->in - fifo->out);

}

 

unsigned int fifo_used(struct fifo *fifo)

{

  return (fifo->in - fifo->out);

}

 

signed int fifo_alloc(struct fifo *fifo, unsigned int size)

{        

/*

         * round down to the next power of 2, since our 'let the indices

         * wrap' technique works only in this case.

         */

        if (!is_power_of_2(size))

                return -1;

 

        fifo->in = 1;

        fifo->out = 1;

        

        if (size < 2){

                fifo->data = NULL;

                fifo->mask = 0;

                return -1;

        }

        fifo->data = malloc(size);

        

        if (!fifo->data){

                fifo->mask = 0;

                return -1;

        }        

        fifo->mask = size - 1;

  

  return 0;

}

 

void fifo_free(struct fifo *fifo)

{

        free(fifo->data);

        fifo->in = 0;

        fifo->out = 0;

        fifo->data = NULL;

        fifo->mask = 0;

}

 

int fifo_init(struct fifo *fifo, unsigned char *buffer, unsigned int size)

{

        if (!is_power_of_2(size))

                return -1;

 

        fifo->in = 0;

        fifo->out = 0;

        fifo->data = buffer;

 

        if (size < 2) {

                fifo->mask = 0;

                return -1;

        }

        fifo->mask = size - 1;

 

        return 0;

}

 

static void fifo_copy_in(struct fifo *fifo, unsigned char *src, unsigned int len, unsigned int off)

{

        unsigned int size = fifo->mask + 1;

        unsigned int l;

 

        off &= fifo->mask;

 

        l = min(len, size - off);

 

        memcpy(fifo->data + off, src, l);

        memcpy(fifo->data, src + l, len - l);

}

 

unsigned int fifo_in(struct fifo *fifo, unsigned char *buf, unsigned int len)

{

        unsigned int l;

 

        l = fifo_unused(fifo);

        if (len > l)

                len = l;

 

        fifo_copy_in(fifo, buf, len, fifo->in);

        fifo->in += len;

        

        return len;

}

 

static void fifo_copy_out(struct fifo *fifo, unsigned char *dst, unsigned int len, unsigned int off)

{

        unsigned int size = fifo->mask + 1;

        unsigned int l;

 

        off &= fifo->mask;

        l = min(len, size - off);

 

        memcpy(dst, fifo->data + off, l);

        memcpy(dst + l, fifo->data, len - l);

}

 

unsigned int fifo_out_peek(struct fifo *fifo, unsigned char *buf, unsigned int len)

{

        unsigned int l;

 

        l = fifo->in - fifo->out;

        if (len > l)

                len = l;

 

        fifo_copy_out(fifo, buf, len, fifo->out);

        return len;

}

 

unsigned int fifo_out(struct fifo *fifo, unsigned char *buf, unsigned int len)

{

        len = fifo_out_peek(fifo, buf, len);

        fifo->out += len;

        return len;

}