帮我写一个stm32f10串口2dma接收数据代码示例包括处理数据完整性和错误检测的完整代码并添加注释解释每一句的意思

好的，以下是示例代码：

#include "stm32f10x.h"

#define BUFFER_SIZE 256

uint8_t buffer[BUFFER_SIZE];
uint8_t buffer_index = 0;

void DMA1_Channel5_IRQHandler(void)
{
    if (DMA_GetITStatus(DMA1_IT_TC5))
    {
        DMA_ClearITPendingBit(DMA1_IT_TC5);
        uint16_t data_length = DMA_GetCurrDataCounter(DMA1_Channel5);
        uint16_t start_index = BUFFER_SIZE - DMA_GetCurrDataCounter(DMA1_Channel5]);
        // 处理数据完整性
        if (data_length == 0 || start_index >= BUFFER_SIZE)
        {
            // 数据不完整或者起始位置错误，丢弃数据
            buffer_index = 0;
            return;
        }
        // 处理错误检测
        uint8_t checksum = 0;
        for (uint16_t i = start_index; i < start_index + data_length - 1; i++)
        {
            checksum ^= buffer[i];
        }
        if (checksum != buffer[start_index + data_length - 1])
        {
            // 校验和错误，丢弃数据
            buffer_index = 0;
            return;
        }
        // 处理正确数据
        // TODO: 在这里添加你的代码
        buffer_index = 0;
    }
}

void USART2_IRQHandler(void)
{
    if (USART_GetITStatus(USART2, USART_IT_RXNE))
    {
        USART_ClearITPendingBit(USART2, USART_IT_RXNE);
        uint8_t data = USART_ReceiveData(USART2);
        if (buffer_index < BUFFER_SIZE)
        {
            buffer[buffer_index++] = data;
        }
    }
}

void init_usart2_dma(void)
{
    // 初始化USART2
    USART_InitTypeDef USART_InitStructure;
    USART_InitStructure.USART_BaudRate = 115200;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx;
    USART_Init(USART2, &USART_InitStructure);
    USART_Cmd(USART2, ENABLE);
    // 初始化DMA
    DMA_InitTypeDef DMA_InitStructure;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART2->DR;
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)buffer;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
    DMA_InitStructure.DMA_BufferSize = BUFFER_SIZE;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel5, &DMA_InitStructure);
    DMA_ITConfig(DMA1_Channel5, DMA_IT_TC, ENABLE);
    DMA_Cmd(DMA1_Channel5, ENABLE);
    // 初始化中断
    NVIC_InitTypeDef NVIC_InitStructure;
    NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel5_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

这是一个使用USART2和DMA接收数据的示例代码，其中包括了处理数据完整性和错误检测的代码。具体来说，当DMA传输完成时，会调用`DMA1_Channel5_IRQHandler`函数，该函数会判断接收到的数据是否完整并且校验和是否正确，如果数据不完整或者校验和错误，则丢弃数据，否则处理正确的数据。当USART2接收到数据时，会调用`USART2_IRQHandler`函数，该函数会将接收到的数据存储到缓冲区中。在使用该代码时，需要先调用`init_usart2_dma`函数来初始化USART2和DMA。