Question for Library 34- STM32F4 as USB HID Device by ftm

/* Include core modules */
#include "stm32f4xx.h"
/* Include my libraries here */
#include "defines.h"
#include "tm_stm32f4_usb_hid_device.h"
#include "tm_stm32f4_delay.h"
#include "tm_stm32f4_disco.h"

void Uart3_Init();
void sendDraggingReport();
TM_USB_HIDDEVICE_Mouse_t Mouse;


int main(void) {
        uint8_t already = 0;

        /* Initialize system */
        SystemInit();

        /* Initialize leds */
        TM_DISCO_LedInit();

        /* Initialize button */
        TM_DISCO_ButtonInit();

        /* Initialize delay */
        TM_DELAY_Init();

        /* Initialize USB HID Device */
        TM_USB_HIDDEVICE_Init();

        /*Initialize USART3*/
        Uart3_Init();

        /* Set default values for mouse struct */
        TM_USB_HIDDEVICE_MouseStructInit(&Mouse);

        while (1) {

                /* If we are connected and drivers are OK */
                /* If you pressed button right now and was not already pressed */

                if (TM_DISCO_ButtonPressed() && already == 0) { /* Button on press */
                        already = 1;

                } else if (!TM_DISCO_ButtonPressed() && already == 1) { /* Button on release */
                        already = 0;

			/* send a dragging report*/
                        sendDraggingReport();
                }
                else {
                        /* Turn off green LED */
                        TM_DISCO_LedOff(LED_GREEN);
                }
        }
}


void Uart3_Init(){
    /******** ?? USART?GPIO ??? ********/
    USART_InitTypeDef USART_InitStructure;
    GPIO_InitTypeDef GPIO_InitStructure;

    /******** ?? GPIOC?USART3 ? RCC ?? ********/
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);

    /******** ? PC10?PC11 ??? USART3 ********/
    GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_USART3);
    GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_USART3);

    /******** ?? PC10 ? Tx ??  ********/
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOC, &GPIO_InitStructure);

    /******** ?? PC11 ? Rx ??  ********/
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
    GPIO_Init(GPIOC, &GPIO_InitStructure);

    /******** USART ?????? ********/
    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(USART3, &USART_InitStructure);

    /******** ?? USART3 ********/
    USART_Cmd(USART3, ENABLE);

    USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
    /* ?? USART3 ?? */
    NVIC_EnableIRQ(USART3_IRQn);
}


uint8_t MouseDataBUFF[5];
int buffIndex = 0;

void USART3_IRQHandler(){

        uint8_t mouse_signal;

        while(USART_GetFlagStatus(USART3, USART_FLAG_RXNE) == RESET){}
        /* read 1 byte via usart3 it */
        mouse_signal = USART_ReceiveData(USART3);

        /*MouseDataBuff spec

                these signals be read from usart3

                index 0 -> Does left button be clicked? 0 is click, 1 is release
                index 1 -> Does right button be clicked? 0 is click, 1 is release
                index 2 -> Does middle button be clicked? 0 is click, 1 is release
                index 3 -> X's movement
                index 4 -> Y's movement
        */

        MouseDataBUFF[buffIndex++] = mouse_signal;

        /*
                        When uart3 get 5 bytes mouse signals, I can decide a set of Mouse value.
        */
        if(buffIndex == 5)
        {
		/* send a dragging report*/
		sendDraggingReport();
		buffIndex = 0;
        }
}

void sendDraggingReport()
{

		Mouse.LeftButton = TM_USB_HIDDEVICE_Button_Pressed;
		Mouse.XAxis = 0;
		Mouse.YAxis = 0;
		TM_USB_HIDDEVICE_MouseSend(&Mouse);


		Mouse.LeftButton = TM_USB_HIDDEVICE_Button_Pressed;
		Mouse.XAxis = 50;
		Mouse.YAxis = 50;
		TM_USB_HIDDEVICE_MouseSend(&Mouse);

		Mouse.LeftButton = TM_USB_HIDDEVICE_Button_Released;
		Mouse.XAxis = 0;
		Mouse.YAxis = 0;
		TM_USB_HIDDEVICE_MouseSend(&Mouse);

}