Intel Extensible Firmware Interface - Manual (Page 601)

Protocols — USB Support
Version 1.10 12/01/02 14-61
EFI_USB_IO_PROTOCOL.UsbGetStringDescriptor()
Summary
Retrieves a Unicode string stored in a USB Device.
Prototype
typedef
EFI_STATUS
(EFIAPI *EFI_USB_IO_GET_STRING_DESCRIPTOR) (
IN EFI_USB_IO_PROTOCOL *This,
IN UINT16 LangID,
IN UINT8 StringID,
OUT CHAR16 **String
);
Parameters
This A pointer to the EFI_USB_IO_PROTOCOL instance. Type
EFI_USB_IO_PROTOCOL is defined in Section 14.2.5.
LangID The Language ID for the string being retrieved. See the
UsbGetSupportedLanguages() function description for a
more detailed description.
StringID The ID of the string being retrieved.
String A pointer to a buffer allocated by this function with
AllocatePool() to store the string. If this function returns
EFI_SUCCESS , it stores the string the caller wants to get. The
caller should release the string buffer with FreePool() after the
string is not used any more.
Description
This function is used to retrieve strings stored in a USB device. Strings are stored in a Unicode
format. The string to retrieve is identified by a language and an identifier. The language is
specified by
LangID , and the identifier is specified by StringID . If the string is found, it is
returned in String , and EFI_SUCCESS is returned. If the string cannot be found, then
EFI_NOT_FOUND is returned. The string buffer is allocated by this function with
AllocatePool() . The caller is responsible for calling FreePool() for String when it is
no longer required.
Status Code Returned
EFI_SUCCESS The string was retrieved successfully.
EFI_NOT_FOUND The string specified by LangID and StringID was not found.
EFI_OUT_OF_RESOURCES There are not enough resources to allocate the return buffer String .