关于usbh_core.c中的USBH_Process(USBH_HandleTypeDef *phost)分析

//主要用于Host枚举的全过程
USBH_StatusTypeDef USBH_Process(USBH_HandleTypeDef *phost)
{
__IO USBH_StatusTypeDef status = USBH_FAIL;
uint8_t idx = 0U;

  /* check for Host port events */
  if (((USBH_IsPortEnabled(phost) == 0U)) && (phost->gState != HOST_IDLE))
  {//如果没设备连接，并且端口没有使能，则更新主机状态
    if(phost->gState != HOST_DEV_DISCONNECTED) //如果状态机不是“未连接”
    {
      phost->gState = HOST_DEV_DISCONNECTED; //则修改为“未连接”
    }
  }

switch (phost->gState)//状态机函数结构
{
case HOST_IDLE :
if (phost->device.is_connected)//设备是否插入
{
/* Wait for 200 ms after connection */
phost->gState = HOST_DEV_WAIT_FOR_ATTACHMENT;//状态机更新到“等待使能端口连接”
USBH_Delay(200U);//为了稳定设备供电
USBH_LL_ResetPort(phost);//主机复位端口，用于连接；如不需要热插拔，则跳过
}
break;

	case HOST_DEV_WAIT_FOR_ATTACHMENT: /* Wait for Port Enabled */
    if (phost->device.PortEnabled == 1U)//端口是否使能
    {
      phost-&g