写一段 STM32 使用HAL库 串口通信使用DMA 发送接受不定长数据的代码

以下是一段使用HAL库实现STM32串口通信使用DMA发送接收不定长数据的代码：

#include "stm32f4xx_hal.h"

#define RX_BUFFER_SIZE 256
#define TX_BUFFER_SIZE 256

UART_HandleTypeDef huart;
DMA_HandleTypeDef hdma_tx;
DMA_HandleTypeDef hdma_rx;

uint8_t tx_buffer[TX_BUFFER_SIZE];
uint8_t rx_buffer[RX_BUFFER_SIZE];
volatile uint16_t rx_rd_index = 0;
volatile uint16_t rx_wr_index = 0;

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
    // Increment the buffer write index
    rx_wr_index++;
    if (rx_wr_index >= RX_BUFFER_SIZE)
    {
        rx_wr_index = 0;
    }
    
    HAL_UART_Receive_DMA(huart, rx_buffer + rx_wr_index, 1);
}

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
    // Do nothing
}

void HAL_UART_ErrorCallback(UART_HandleTypeDef *huart)
{
    // Do nothing
}

void init_uart_dma()
{
    // Initialize the UART handle structure
    huart.Instance = USART1;
    huart.Init.BaudRate = 9600;
    huart.Init.WordLength = UART_WORDLENGTH_8B;
    huart.Init.StopBits = UART_STOPBITS_1;
    huart.Init.Parity = UART_PARITY_NONE;
    huart.Init.Mode = UART_MODE_TX_RX;
    huart.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    huart.Init.OverSampling = UART_OVERSAMPLING_16;
    if(HAL_UART_Init(&huart) != HAL_OK)
    {
        Error_Handler();
    }
    
    // Enable UART DMA transmission and reception
    __HAL_RCC_DMA2_CLK_ENABLE();
    
    hdma_tx.Instance = DMA2_Stream7;
    hdma_tx.Init.Channel = DMA_CHANNEL_4;
    hdma_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;
    hdma_tx.Init.PeriphInc = DMA_PINC_DISABLE;
    hdma_tx.Init.MemInc = DMA_MINC_ENABLE;
    hdma_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
    hdma_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
    hdma_tx.Init.Mode = DMA_NORMAL;
    hdma_tx.Init.Priority = DMA_PRIORITY_LOW;
    hdma_tx.Init.FIFOMode = DMA_FIFOMODE_ENABLE;
    hdma_tx.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
    hdma_tx.Init.MemBurst = DMA_MBURST_SINGLE;
    hdma_tx.Init.PeriphBurst = DMA_PBURST_SINGLE;
    if (HAL_DMA_Init(&hdma_tx) != HAL_OK)
    {
        Error_Handler();
    }
    
    hdma_rx.Instance = DMA2_Stream2;
    hdma_rx.Init.Channel = DMA_CHANNEL_4;
    hdma_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
    hdma_rx.Init.PeriphInc = DMA_PINC_DISABLE;
    hdma_rx.Init.MemInc = DMA_MINC_ENABLE;
    hdma_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
    hdma_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
    hdma_rx.Init.Mode = DMA_CIRCULAR;
    hdma_rx.Init.Priority = DMA_PRIORITY_LOW;
    hdma_rx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
    if (HAL_DMA_Init(&hdma_rx) != HAL_OK)
    {
        Error_Handler();
    }
    
    __HAL_LINKDMA(&huart, hdmatx, hdma_tx);
    __HAL_LINKDMA(&huart, hdmarx, hdma_rx);
    
    HAL_NVIC_SetPriority(DMA2_Stream7_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(DMA2_Stream7_IRQn);
    
    HAL_NVIC_SetPriority(DMA2_Stream2_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(DMA2_Stream2_IRQn);
    
    HAL_UART_Receive_DMA(&huart, rx_buffer, 1);
}

void send_uart_packet(uint8_t *data, uint16_t length)
{
    // Copy the data to the TX buffer
    memcpy(tx_buffer, data, length);
    
    // Enable UART transmission DMA
    HAL_UART_Transmit_DMA(&huart, tx_buffer, length);
}

int read_uart_packet(uint8_t *buffer, uint16_t buffer_size)
{
    int packet_size = 0;
    
    // Get the buffer read index
    uint16_t rd_index = RX_BUFFER_SIZE - __HAL_DMA_GET_COUNTER(&hdma_rx);
    
    // If the read index has changed
    if (rd_index != rx_rd_index)
    {
        if (rd_index > rx_rd_index)
        {
            packet_size = rd_index - rx_rd_index;
        }
        else
        {
            packet_size = RX_BUFFER_SIZE - rx_rd_index + rd_index;
        }
        
        // Check that the buffer size is large enough
        if (packet_size > buffer_size)
        {
            packet_size = buffer_size;
        }
        
        // Copy the data to the buffer
        if (rx_rd_index + packet_size < RX_BUFFER_SIZE)
        {
            memcpy(buffer, rx_buffer + rx_rd_index, packet_size);
        }
        else
        {
            memcpy(buffer, rx_buffer + rx_rd_index, RX_BUFFER_SIZE - rx_rd_index);
            memcpy(buffer + RX_BUFFER_SIZE - rx_rd_index, rx_buffer, packet_size - (RX_BUFFER_SIZE - rx_rd_index));
        }
        
        // Update the read index
        rx_rd_index = rd_index;
    }
    
    return packet_size;
}

int main(void)
{
    HAL_Init();
    
    init_uart_dma();
    
    while (1)
    {
        uint8_t buffer[32];
        int packet_size = read_uart_packet(buffer, 32);
        if (packet_size > 0)
        {
            // Do something with the received packet
        }
    }
}

void DMA2_Stream7_IRQHandler(void)
{
    HAL_DMA_IRQHandler(&hdma_tx);
}

void DMA2_Stream2_IRQHandler(void)
{
    HAL_DMA_IRQHandler(&hdma_rx);
}