本文章主要针对沁恒科技的CH58x芯片，以 BLE_UART 工程为依托，介绍串口数据的接收与处理。
该工程中串口数据的处理用到了环形FIFO机制，可作为其他开发工具

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【沁恒蓝牙mesh】CH58x串口环形FIFO数据处理

1. 串口数据处理的几个问题
2. 环形FIFO图示
3. 代码思路解析
- 3.1 数据流向过程解析
- 3.2 buffer_size_mask 解析
- - 3.3【fifo初始化】
  - 3.4【状态判断】
  - 3.5【数据写入与读出】
4. 代码示例
- 4.1 app_drv_fifo.h
- 4.2 app_drv_fifo.c

1. 串口数据处理的几个问题

考虑几个问题：

读取速度大于写入速度时，会读取到空数据
当写入速度大于读取速度时，会出现数据覆盖的情况（这是不允许的）

2. 环形FIFO图示

假设定义一个 size 为10 的环形FIFO缓冲区，下图分别表示：

初始化
写入5个字节
读取4个字节
写入9个字节

fifo缓冲区的长度

fifo->end - fifo->begin

3. 代码思路解析

本文以南京沁恒微电子公司的 CH583 提供的 SDK中的 BLE_UART 工程为例，解析串口数据解析的过程， .c 和 .h 置于文末供参考备份。

3.1 数据流向过程解析

1️⃣ : 定义fifo 缓冲区以及发送接收数组

typedef struct Fifo_s
{uint16_t begin;uint16_t end;uint8_t *data;uint16_t size;uint16_t size_mask;
} app_drv_fifo_t;static uint8_t app_uart_tx_buffer[APP_UART_TX_BUFFER_LENGTH] = {0};   // 512
static uint8_t app_uart_rx_buffer[APP_UART_RX_BUFFER_LENGTH] = {0};   // 2048static app_drv_fifo_t app_uart_tx_fifo;
static app_drv_fifo_t app_uart_rx_fifo;

初始化：

2️⃣ :在串口接收中断中，将接收FIFO寄存器中的数据写入 app_uart_rx_fifo，并将接收一帧数据完成的标志位置1；

void UART3_IRQHandler(void){switch(UART3_GetITFlag()){case UART_II_RECV_TOUT:  /*接收fifo一段时间内没有数据，产生超时中断*//*将R8_UART3_RBR 寄存器中的数据，长度为 R8_UART3_RFC ，写入 rx_fifo  */error = app_drv_fifo_write_from_same_addr(&app_uart_rx_fifo, (uint8_t *)&R8_UART3_RBR, R8_UART3_RFC);uart_rx_flag = true;   /*表示接口完成一次数据*/break;     }
}

app_drv_fifo_write_from_same_addr ：将硬件 rx fifo 寄存器中的数据读出，存储到 rx_fifo中， push data to fifo

app_drv_fifo_read_to_same_addr : 将硬件 tx fifo 寄存器中的数据读出，存储到 tx_fifo 中， pop data from fifo

3.2 buffer_size_mask 解析

3.3【fifo初始化】

typedef struct Fifo_s
{uint16_t begin;uint16_t end;uint8_t *data;uint16_t size;uint16_t size_mask;   
} app_drv_fifo_t;// size_mask = size - 1
// 通过判断  size & (size -1 )  == 0  限制，size大小必须为 2 的整数次幂// 比如初始化一个 fifo ，长度为 16 ；
uint8_t uart_buffer[16] = {0};   // 512
static app_drv_fifo_t uart_fifo;uart_fifo.begin = uart_fifo.end = 0;
uart_fifo.size =16;
uart_fifo.size_mask = 16 -1;
uart_fifo.data = &uart_buffer[0];

3.4【状态判断】

// 刷新 fifo
void app_drv_fifo_flush(app_drv_fifo_t *fifo){fifo->begin = 0;fifo->end = 0;
}
// 判断已经占用的长度
uint16_t app_drv_fifo_length(app_drv_fifo_t *fifo){uint16_t tmp = fifo->begin;return fifo->end - tmp;
}// 判断空
bool app_drv_fifo_is_empty(app_drv_fifo_t *fifo){return (fifo->begin == fifo->end);
}// 判断满
bool app_drv_fifo_is_full(app_drv_fifo_t *fifo){	return ((fifo->end - fifo->begin) == fifo->size);
}

3.5【数据写入与读出】

关于唤醒FIFO防止数组索引溢出，有时候还采用， (begin + size - out ) % size

/*将一组数据 push到fifo中*/
void app_drv_fifo_push(app_drv_fifo_t *fifo, uint8_t data){uint16_t index = fifo->end & fifo->size_mask; /*将数组的index永远限制在 0:size-1 范围内，不会越界*/fifo->data[index] = data;  /*为了保证数组不越界 */fifo->end++;
}/*将fifo中的最后一个元素 pop出来*/
uint8_t app_drv_fifo_pop(app_drv_fifo_t *fifo){uint16_t index = fifo->end & fifo->size_mask;fifo->data[index] = data;  /*为了保证数组不越界 */return data;
}// 若 a = 2^n - 1   即 a = 3  7 15 这些数字
// 则 n & (a-1) 的结果就是，将n的结果分组：
// 假设 a = 16;  则 n & 15 的结果就是：/*n = 0-15   结果为 0-15n = 16-31  结果为 0-15 
*/

4. 代码示例

4.1 app_drv_fifo.h

/********************************** (C) COPYRIGHT ******************************** File Name          : app_drv_fifo.h* Author             : WCH* Version            : V1.1* Date               : 2022/01/19* Description        :********************************************************************************** Copyright (c) 2021 Nanjing Qinheng Microelectronics Co., Ltd.* Attention: This software (modified or not) and binary are used for * microcontroller manufactured by Nanjing Qinheng Microelectronics.*******************************************************************************/#ifndef __APP_DRV_FIFO_H__
#define __APP_DRV_FIFO_H__#include <stdbool.h>
#include <stdint.h>#ifndef BV#define BV(n)    (1 << (n))
#endif#ifndef BF#define BF(x, b, s)    (((x) & (b)) >> (s))
#endif#ifndef MIN#define MIN(n, m)    (((n) < (m)) ? (n) : (m))
#endif#ifndef MAX#define MAX(n, m)    (((n) < (m)) ? (m) : (n))
#endif#ifndef ABS#define ABS(n)    (((n) < 0) ? -(n) : (n))
#endiftypedef enum
{APP_DRV_FIFO_RESULT_SUCCESS = 0,APP_DRV_FIFO_RESULT_LENGTH_ERROR,APP_DRV_FIFO_RESULT_NOT_FOUND,APP_DRV_FIFO_RESULT_NOT_MEM,APP_DRV_FIFO_RESULT_NULL,} app_drv_fifo_result_t;#ifndef NULL#define NULL    0
#endif/*!* FIFO structure*/
typedef struct Fifo_s
{uint16_t begin;uint16_t end;uint8_t *data;uint16_t size;uint16_t size_mask;
} app_drv_fifo_t;//__inline uint16_t app_drv_fifo_length(app_drv_fifo_t *fifo);uint16_t app_drv_fifo_length(app_drv_fifo_t *fifo);/*!* Initializes the FIFO structure** \param [IN] fifo   Pointer to the FIFO object* \param [IN] buffer Buffer to be used as FIFO* \param [IN] size   size of the buffer*/
app_drv_fifo_result_t
app_drv_fifo_init(app_drv_fifo_t *fifo, uint8_t *buffer, uint16_t buffer_size);/*!* Pushes data to the FIFO** \param [IN] fifo Pointer to the FIFO object* \param [IN] data data to be pushed into the FIFO*/
void app_drv_fifo_push(app_drv_fifo_t *fifo, uint8_t data);/*!* Pops data from the FIFO** \param [IN] fifo Pointer to the FIFO object* \retval data     data popped from the FIFO*/
uint8_t app_drv_fifo_pop(app_drv_fifo_t *fifo);/*!* Flushes the FIFO** \param [IN] fifo   Pointer to the FIFO object*/
void app_drv_fifo_flush(app_drv_fifo_t *fifo);/*!* Checks if the FIFO is empty** \param [IN] fifo   Pointer to the FIFO object* \retval isEmpty    true: FIFO is empty, false FIFO is not empty*/
bool app_drv_fifo_is_empty(app_drv_fifo_t *fifo);/*!* Checks if the FIFO is full** \param [IN] fifo   Pointer to the FIFO object* \retval isFull     true: FIFO is full, false FIFO is not full*/
bool app_drv_fifo_is_full(app_drv_fifo_t *fifo);app_drv_fifo_result_t
app_drv_fifo_write(app_drv_fifo_t *fifo, uint8_t *data,uint16_t *p_write_length);app_drv_fifo_result_t
app_drv_fifo_write_from_same_addr(app_drv_fifo_t *fifo, uint8_t *data,uint16_t write_length);app_drv_fifo_result_t
app_drv_fifo_read(app_drv_fifo_t *fifo, uint8_t *data, uint16_t *p_read_length);app_drv_fifo_result_t
app_drv_fifo_read_to_same_addr(app_drv_fifo_t *fifo, uint8_t *data,uint16_t read_length);#endif // __APP_DRV_FIFO_H__

4.2 app_drv_fifo.c

/********************************** (C) COPYRIGHT ******************************** File Name          : app_drv_fifo.c* Author             : WCH* Version            : V1.1* Date               : 2022/01/19* Description        :********************************************************************************** Copyright (c) 2021 Nanjing Qinheng Microelectronics Co., Ltd.* Attention: This software (modified or not) and binary are used for * microcontroller manufactured by Nanjing Qinheng Microelectronics.*******************************************************************************/#include "app_drv_fifo.h"static __inline uint16_t fifo_length(app_drv_fifo_t *fifo)
{uint16_t tmp = fifo->begin;return fifo->end - tmp;
}uint16_t app_drv_fifo_length(app_drv_fifo_t *fifo)
{return fifo_length(fifo);
}app_drv_fifo_result_t
app_drv_fifo_init(app_drv_fifo_t *fifo, uint8_t *buffer, uint16_t buffer_size)
{if(buffer_size == 0){return APP_DRV_FIFO_RESULT_LENGTH_ERROR;}if(0 != ((buffer_size) & (buffer_size - 1))){return APP_DRV_FIFO_RESULT_LENGTH_ERROR;}fifo->begin = 0;fifo->end = 0;fifo->data = buffer;fifo->size = buffer_size;fifo->size_mask = buffer_size - 1;return APP_DRV_FIFO_RESULT_SUCCESS;
}void app_drv_fifo_push(app_drv_fifo_t *fifo, uint8_t data)
{fifo->data[fifo->end & fifo->size_mask] = data;fifo->end++;
}uint8_t app_drv_fifo_pop(app_drv_fifo_t *fifo)
{uint8_t data = fifo->data[fifo->begin & fifo->size_mask];fifo->begin++;return data;
}void app_drv_fifo_flush(app_drv_fifo_t *fifo)
{fifo->begin = 0;fifo->end = 0;
}bool app_drv_fifo_is_empty(app_drv_fifo_t *fifo)
{return (fifo->begin == fifo->end);
}bool app_drv_fifo_is_full(app_drv_fifo_t *fifo)
{return (fifo_length(fifo) == fifo->size);
}app_drv_fifo_result_t
app_drv_fifo_write(app_drv_fifo_t *fifo, uint8_t *data, uint16_t *p_write_length)
{if(fifo == NULL){return APP_DRV_FIFO_RESULT_NULL;}if(p_write_length == NULL){return APP_DRV_FIFO_RESULT_NULL;}//PRINT("fifo_length = %d\r\n",fifo_length(fifo));const uint16_t available_count = fifo->size - fifo_length(fifo);const uint16_t requested_len = (*p_write_length);uint16_t       index = 0;uint16_t       write_size = MIN(requested_len, available_count);//PRINT("available_count %d\r\n",available_count);// Check if the FIFO is FULL.if(available_count == 0){return APP_DRV_FIFO_RESULT_NOT_MEM;}// Check if application has requested only the size.if(data == NULL){return APP_DRV_FIFO_RESULT_SUCCESS;}for(index = 0; index < write_size; index++){//pushfifo->data[fifo->end & fifo->size_mask] = data[index];fifo->end++;}(*p_write_length) = write_size;return APP_DRV_FIFO_RESULT_SUCCESS;
}app_drv_fifo_result_t
app_drv_fifo_write_from_same_addr(app_drv_fifo_t *fifo, uint8_t *data, uint16_t write_length)
{if(fifo == NULL){return APP_DRV_FIFO_RESULT_NULL;}const uint16_t available_count = fifo->size_mask - fifo_length(fifo) + 1;const uint16_t requested_len = (write_length);uint16_t       index = 0;uint16_t       write_size = MIN(requested_len, available_count);// Check if the FIFO is FULL.if(available_count == 0){return APP_DRV_FIFO_RESULT_NOT_MEM;}for(index = 0; index < write_size; index++){//pushfifo->data[fifo->end & fifo->size_mask] = data[0];fifo->end++;}return APP_DRV_FIFO_RESULT_SUCCESS;
}app_drv_fifo_result_t
app_drv_fifo_read(app_drv_fifo_t *fifo, uint8_t *data, uint16_t *p_read_length)
{if(fifo == NULL){return APP_DRV_FIFO_RESULT_NULL;}if(p_read_length == NULL){return APP_DRV_FIFO_RESULT_NULL;}const uint16_t byte_count = fifo_length(fifo);const uint16_t requested_len = (*p_read_length);uint32_t       index = 0;uint32_t       read_size = MIN(requested_len, byte_count);if(byte_count == 0){return APP_DRV_FIFO_RESULT_NOT_FOUND;}//PRINT("read size = %d,byte_count = %d\r\n",read_size,byte_count);for(index = 0; index < read_size; index++){//popdata[index] = fifo->data[fifo->begin & fifo->size_mask];fifo->begin++;}(*p_read_length) = read_size;return APP_DRV_FIFO_RESULT_SUCCESS;
}app_drv_fifo_result_t
app_drv_fifo_read_to_same_addr(app_drv_fifo_t *fifo, uint8_t *data, uint16_t read_length)
{if(fifo == NULL){return APP_DRV_FIFO_RESULT_NULL;}const uint16_t byte_count = fifo_length(fifo);const uint16_t requested_len = (read_length);uint32_t       index = 0;uint32_t       read_size = MIN(requested_len, byte_count);for(index = 0; index < read_size; index++){//popdata[0] = fifo->data[fifo->begin & fifo->size_mask];fifo->begin++;}return APP_DRV_FIFO_RESULT_SUCCESS;
}