关于USBD_CreateConfigurationRequestEx的实现

USBD_CreateConfigurationRequestEx（）是用来格式化URB的，URB发送到USB总线驱动程序完成真正的配置操作。

UsbBuildSelectConfigurationRequest（）通常是将最后一个参数设置为NULL来卸载USB的当前配置的。

 

PURB
STDCALL
USBD_CreateConfigurationRequestEx(
    PUSB_CONFIGURATION_DESCRIPTOR ConfigurationDescriptor,
    PUSBD_INTERFACE_LIST_ENTRY InterfaceList
    )
{
    PURB Urb;
    DWORD UrbSize;
    DWORD InterfaceCount;

    for (InterfaceCount = 0;
         InterfaceList[InterfaceCount].InterfaceDescriptor != NULL;
         ++InterfaceCount)
       ;
   
    ++InterfaceCount;

    UrbSize = sizeof(Urb->UrbSelectConfiguration) +
       (InterfaceCount * sizeof(PUSBD_INTERFACE_LIST_ENTRY));
    Urb = ExAllocatePool(NonPagedPool, UrbSize);
    Urb->UrbSelectConfiguration.Hdr.Function =
        URB_FUNCTION_SELECT_CONFIGURATION;       
    Urb->UrbSelectConfiguration.Hdr.Length =
        sizeof(Urb->UrbSelectConfiguration);
    Urb->UrbSelectConfiguration.ConfigurationDescriptor =
       ConfigurationDescriptor;
    memcpy((PVOID)&Urb->UrbSelectConfiguration.Interface, (PVOID)InterfaceList,
       InterfaceCount * sizeof(PUSBD_INTERFACE_LIST_ENTRY));

    return Urb;
}

 

USBD_CreateConfigurationRequestEx（）是用来格式化URB的，URB发送到USB总线驱动程序完成真正的配置操作。

UsbBuildSelectConfigurationRequest（）通常是将最后一个参数设置为NULL来卸载USB的当前配置的。

 

PURB
STDCALL
USBD_CreateConfigurationRequestEx(
    PUSB_CONFIGURATION_DESCRIPTOR ConfigurationDescriptor,
    PUSBD_INTERFACE_LIST_ENTRY InterfaceList
    )
{
    PURB Urb;
    DWORD UrbSize;
    DWORD InterfaceCount;

    for (InterfaceCount = 0;
         InterfaceList[InterfaceCount].InterfaceDescriptor != NULL;
         ++InterfaceCount)
       ;
   
    ++InterfaceCount;

    UrbSize = sizeof(Urb->UrbSelectConfiguration) +
       (InterfaceCount * sizeof(PUSBD_INTERFACE_LIST_ENTRY));
    Urb = ExAllocatePool(NonPagedPool, UrbSize);
    Urb->UrbSelectConfiguration.Hdr.Function =
        URB_FUNCTION_SELECT_CONFIGURATION;       
    Urb->UrbSelectConfiguration.Hdr.Length =
        sizeof(Urb->UrbSelectConfiguration);
    Urb->UrbSelectConfiguration.ConfigurationDescriptor =
       ConfigurationDescriptor;
    memcpy((PVOID)&Urb->UrbSelectConfiguration.Interface, (PVOID)InterfaceList,
       InterfaceCount * sizeof(PUSBD_INTERFACE_LIST_ENTRY));

    return Urb;
}

 

对于Multiple Interfaces的USB设备，用UsbBuildSelectInterfaceRequest（）来选择接口: 实际上是格式化URB，以待发送给USB总线驱动程序。

 

通常的流程：先取得目标配置的配置描述符，然后调用USBD_ParseConfigurationDescriptor（）来辅助得到PUSBD_INTERFACE_INFORMATION List, 设置带宽等参数后，接着调用USBD_CreateConfigurationRequestEx()生成URB，然后发送到USB总线驱动程序完成配置。接下来就可以调用UsbBuildSelectConfigurationRequest（）来选择接口。