帮我写一个stm32f10串口1通过DMA1循环接收数据的完整代码实例并添加注释

当然可以，下面是示例代码，带有注释：

#include "stm32f10x.h"

void USART1_DMA_Init(void) {
    USART_InitTypeDef USART_InitStructure;
    DMA_InitTypeDef   DMA_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

    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(USART1, &USART_InitStructure);
    USART_Cmd(USART1, ENABLE);

    DMA_DeInit(DMA1_Channel5);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) & (USART1->DR);
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&USART1_DMA_Buffer;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
    DMA_InitStructure.DMA_BufferSize = 256; // 定义一次接收数据的大小
    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_Cmd(DMA1_Channel5, ENABLE);
    USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE);
}

int main(void) {
    USART1_DMA_Init();
    while (1) {
    }
}

// 当有数据接收时，会自动调用下面的中断服务处理函数，可以在这里处理数据
void DMA1_Channel5_IRQHandler(void)
{
   if (DMA_GetITStatus(DMA1_IT_TC5) != RESET)
   {
     DMA_ClearITPendingBit(DMA1_IT_TC5);
     // 处理接收到的数据
   }
 }

这个代码中实现了通过stm32f10串口1通过DMA1循环接收数据，每次接收256字节数据，然后自动清空接收缓存区并且循环接收。当然，这只是一个示例，实际应用中还需要根据具体业务需求进行修改。