请给我一段stm32f103c8t6配置USART的代码，需要用到DMA通道

以下是一个基本的USART配置代码，使用DMA通道：

#include "stm32f10x.h"
#include "stm32f10x_dma.h"
#include "stm32f10x_usart.h"
#include "stm32f10x_gpio.h"

#define BUFFER_SIZE 100

uint8_t tx_buffer[BUFFER_SIZE];
uint8_t rx_buffer[BUFFER_SIZE];

void DMA_Configuration(void)
{
    DMA_InitTypeDef DMA_InitStructure;

    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

    DMA_DeInit(DMA1_Channel4);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART1->DR);
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)tx_buffer;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
    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_Normal;
    DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel4, &DMA_InitStructure);

    DMA_DeInit(DMA1_Channel5);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART1->DR);
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)rx_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_Normal;
    DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel5, &DMA_InitStructure);

    USART_DMACmd(USART1, USART_DMAReq_Tx | USART_DMAReq_Rx, ENABLE);

    DMA_Cmd(DMA1_Channel4, ENABLE);
    DMA_Cmd(DMA1_Channel5, ENABLE);
}

void USART_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    USART_InitStructure.USART_BaudRate = 9600;
    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_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

int main(void)
{
    USART_Configuration();
    DMA_Configuration();

    while (1)
    {
        // do something
    }
}

该代码配置了USART1在GPIOA9和GPIOA10上，使用了DMA通道4和5。USART的波特率被设置为9600。该程序使用了两个无限循环，一个在主函数中，一个在DMA中断中。当USART接收到数据时，它会通过DMA传输到rx_buffer中。当需要发送数据时，数据会从tx_buffer中传输到USART中。