MdePkg/Include/Library/DevicePathLib.h - edk2 - Git at Google

 /** @file
   Provides library functions to construct and parse UEFI Device Paths.

   This library provides defines, macros, and functions to help create and parse
   EFI_DEVICE_PATH_PROTOCOL structures.

 Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials are licensed and made available under
 the terms and conditions of the BSD License that accompanies this distribution.
 The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php.

 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

 **/

 #ifndef __DEVICE_PATH_LIB_H__
 #define __DEVICE_PATH_LIB_H__

 #define END_DEVICE_PATH_LENGTH               (sizeof (EFI_DEVICE_PATH_PROTOCOL))

 /**
   Determine whether a given device path is valid.
   If DevicePath is NULL, then ASSERT().

   @param  DevicePath  A pointer to a device path data structure.
   @param  MaxSize     The maximum size of the device path data structure.

   @retval TRUE        DevicePath is valid.
   @retval FALSE       The length of any node node in the DevicePath is less
                       than sizeof (EFI_DEVICE_PATH_PROTOCOL).
   @retval FALSE       If MaxSize is not zero, the size of the DevicePath
                       exceeds MaxSize.
   @retval FALSE       If PcdMaximumDevicePathNodeCount is not zero, the node
                       count of the DevicePath exceeds PcdMaximumDevicePathNodeCount.
 **/
 BOOLEAN
 EFIAPI
 IsDevicePathValid (
   IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath,
   IN       UINTN                    MaxSize
   );

 /**
   Returns the Type field of a device path node.

   Returns the Type field of the device path node specified by Node.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

   @return The Type field of the device path node specified by Node.

 **/
 UINT8
 EFIAPI
 DevicePathType (
   IN CONST VOID  *Node
   );

 /**
   Returns the SubType field of a device path node.

   Returns the SubType field of the device path node specified by Node.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

   @return The SubType field of the device path node specified by Node.

 **/
 UINT8
 EFIAPI
 DevicePathSubType (
   IN CONST VOID  *Node
   );

 /**
   Returns the 16-bit Length field of a device path node.

   Returns the 16-bit Length field of the device path node specified by Node.
   Node is not required to be aligned on a 16-bit boundary, so it is recommended
   that a function such as ReadUnaligned16() be used to extract the contents of
   the Length field.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

   @return The 16-bit Length field of the device path node specified by Node.

 **/
 UINTN
 EFIAPI
 DevicePathNodeLength (
   IN CONST VOID  *Node
   );

 /**
   Returns a pointer to the next node in a device path.

   Returns a pointer to the device path node that follows the device path node specified by Node.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

   @return a pointer to the device path node that follows the device path node specified by Node.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 NextDevicePathNode (
   IN CONST VOID  *Node
   );

 /**
   Determines if a device path node is an end node of a device path.
   This includes nodes that are the end of a device path instance and nodes that
   are the end of an entire device path.

   Determines if the device path node specified by Node is an end node of a device path.
   This includes nodes that are the end of a device path instance and nodes that are the
   end of an entire device path.  If Node represents an end node of a device path,
   then TRUE is returned.  Otherwise, FALSE is returned.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

   @retval TRUE      The device path node specified by Node is an end node of a device path.
   @retval FALSE     The device path node specified by Node is not an end node of a device path.

 **/
 BOOLEAN
 EFIAPI
 IsDevicePathEndType (
   IN CONST VOID  *Node
   );

 /**
   Determines if a device path node is an end node of an entire device path.

   Determines if a device path node specified by Node is an end node of an entire device path.
   If Node represents the end of an entire device path, then TRUE is returned.
   Otherwise, FALSE is returned.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

   @retval TRUE      The device path node specified by Node is the end of an entire device path.
   @retval FALSE     The device path node specified by Node is not the end of an entire device path.

 **/
 BOOLEAN
 EFIAPI
 IsDevicePathEnd (
   IN CONST VOID  *Node
   );

 /**
   Determines if a device path node is an end node of a device path instance.

   Determines if a device path node specified by Node is an end node of a device path instance.
   If Node represents the end of a device path instance, then TRUE is returned.
   Otherwise, FALSE is returned.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

   @retval TRUE      The device path node specified by Node is the end of a device path instance.
   @retval FALSE     The device path node specified by Node is not the end of a device path instance.

 **/
 BOOLEAN
 EFIAPI
 IsDevicePathEndInstance (
   IN CONST VOID  *Node
   );

 /**
   Sets the length, in bytes, of a device path node.

   Sets the length of the device path node specified by Node to the value specified
   by NodeLength.  NodeLength is returned.  Node is not required to be aligned on
   a 16-bit boundary, so it is recommended that a function such as WriteUnaligned16()
   be used to set the contents of the Length field.

   If Node is NULL, then ASSERT().
   If NodeLength >= 0x10000, then ASSERT().
   If NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL), then ASSERT().

   @param  Node      A pointer to a device path node data structure.
   @param  Length    The length, in bytes, of the device path node.

   @return Length

 **/
 UINT16
 EFIAPI
 SetDevicePathNodeLength (
   IN OUT VOID  *Node,
   IN UINTN     Length
   );

 /**
   Fills in all the fields of a device path node that is the end of an entire device path.

   Fills in all the fields of a device path node specified by Node so Node represents
   the end of an entire device path.  The Type field of Node is set to
   END_DEVICE_PATH_TYPE, the SubType field of Node is set to
   END_ENTIRE_DEVICE_PATH_SUBTYPE, and the Length field of Node is set to
   END_DEVICE_PATH_LENGTH.  Node is not required to be aligned on a 16-bit boundary,
   so it is recommended that a function such as WriteUnaligned16() be used to set
   the contents of the Length field.

   If Node is NULL, then ASSERT().

   @param  Node      A pointer to a device path node data structure.

 **/
 VOID
 EFIAPI
 SetDevicePathEndNode (
   OUT VOID  *Node
   );

 /**
   Returns the size of a device path in bytes.

   This function returns the size, in bytes, of the device path data structure
   specified by DevicePath including the end of device path node.
   If DevicePath is NULL or invalid, then 0 is returned.

   @param  DevicePath  A pointer to a device path data structure.

   @retval 0           If DevicePath is NULL or invalid.
   @retval Others      The size of a device path in bytes.

 **/
 UINTN
 EFIAPI
 GetDevicePathSize (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   );

 /**
   Creates a new copy of an existing device path.

   This function allocates space for a new copy of the device path specified by DevicePath.  If
   DevicePath is NULL, then NULL is returned.  If the memory is successfully allocated, then the
   contents of DevicePath are copied to the newly allocated buffer, and a pointer to that buffer
   is returned.  Otherwise, NULL is returned.
   The memory for the new device path is allocated from EFI boot services memory.
   It is the responsibility of the caller to free the memory allocated.

   @param  DevicePath                 A pointer to a device path data structure.

   @retval NULL    DevicePath is NULL or invalid.
   @retval Others  A pointer to the duplicated device path.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 DuplicateDevicePath (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   );

 /**
   Creates a new device path by appending a second device path to a first device path.

   This function creates a new device path by appending a copy of SecondDevicePath to a copy of
   FirstDevicePath in a newly allocated buffer.  Only the end-of-device-path device node from
   SecondDevicePath is retained. The newly created device path is returned.
   If FirstDevicePath is NULL, then it is ignored, and a duplicate of SecondDevicePath is returned.
   If SecondDevicePath is NULL, then it is ignored, and a duplicate of FirstDevicePath is returned.
   If both FirstDevicePath and SecondDevicePath are NULL, then a copy of an end-of-device-path is
   returned.
   If there is not enough memory for the newly allocated buffer, then NULL is returned.
   The memory for the new device path is allocated from EFI boot services memory. It is the
   responsibility of the caller to free the memory allocated.

   @param  FirstDevicePath            A pointer to a device path data structure.
   @param  SecondDevicePath           A pointer to a device path data structure.

   @retval NULL      If there is not enough memory for the newly allocated buffer.
   @retval NULL      If FirstDevicePath or SecondDevicePath is invalid.
   @retval Others    A pointer to the new device path if success.
                     Or a copy an end-of-device-path if both FirstDevicePath and SecondDevicePath are NULL.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 AppendDevicePath (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *FirstDevicePath,  OPTIONAL
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *SecondDevicePath  OPTIONAL
   );

 /**
   Creates a new path by appending the device node to the device path.

   This function creates a new device path by appending a copy of the device node specified by
   DevicePathNode to a copy of the device path specified by DevicePath in an allocated buffer.
   The end-of-device-path device node is moved after the end of the appended device node.
   If DevicePathNode is NULL then a copy of DevicePath is returned.
   If DevicePath is NULL then a copy of DevicePathNode, followed by an end-of-device path device
   node is returned.
   If both DevicePathNode and DevicePath are NULL then a copy of an end-of-device-path device node
   is returned.
   If there is not enough memory to allocate space for the new device path, then NULL is returned.
   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
   free the memory allocated.

   @param  DevicePath                 A pointer to a device path data structure.
   @param  DevicePathNode             A pointer to a single device path node.

   @retval NULL      There is not enough memory for the new device path.
   @retval Others    A pointer to the new device path if success.
                     A copy of DevicePathNode followed by an end-of-device-path node
                     if both FirstDevicePath and SecondDevicePath are NULL.
                     A copy of an end-of-device-path node if both FirstDevicePath and SecondDevicePath are NULL.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 AppendDevicePathNode (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath,     OPTIONAL
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePathNode  OPTIONAL
   );

 /**
   Creates a new device path by appending the specified device path instance to the specified device
   path.

   This function creates a new device path by appending a copy of the device path instance specified
   by DevicePathInstance to a copy of the device path secified by DevicePath in a allocated buffer.
   The end-of-device-path device node is moved after the end of the appended device path instance
   and a new end-of-device-path-instance node is inserted between.
   If DevicePath is NULL, then a copy if DevicePathInstance is returned.
   If DevicePathInstance is NULL, then NULL is returned.
   If DevicePath or DevicePathInstance is invalid, then NULL is returned.
   If there is not enough memory to allocate space for the new device path, then NULL is returned.
   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
   free the memory allocated.

   @param  DevicePath                 A pointer to a device path data structure.
   @param  DevicePathInstance         A pointer to a device path instance.

   @return A pointer to the new device path.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 AppendDevicePathInstance (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath,        OPTIONAL
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePathInstance OPTIONAL
   );

 /**
   Creates a copy of the current device path instance and returns a pointer to the next device path
   instance.

   This function creates a copy of the current device path instance. It also updates DevicePath to
   point to the next device path instance in the device path (or NULL if no more) and updates Size
   to hold the size of the device path instance copy.
   If DevicePath is NULL, then NULL is returned.
   If DevicePath points to a invalid device path, then NULL is returned.
   If there is not enough memory to allocate space for the new device path, then NULL is returned.
   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
   free the memory allocated.
   If Size is NULL, then ASSERT().

   @param  DevicePath                 On input, this holds the pointer to the current device path
                                      instance. On output, this holds the pointer to the next device
                                      path instance or NULL if there are no more device path
                                      instances in the device path pointer to a device path data
                                      structure.
   @param  Size                       On output, this holds the size of the device path instance, in
                                      bytes or zero, if DevicePath is NULL.

   @return A pointer to the current device path instance.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 GetNextDevicePathInstance (
   IN OUT EFI_DEVICE_PATH_PROTOCOL    **DevicePath,
   OUT UINTN                          *Size
   );

 /**
   Creates a device node.

   This function creates a new device node in a newly allocated buffer of size NodeLength and
   initializes the device path node header with NodeType and NodeSubType.  The new device path node
   is returned.
   If NodeLength is smaller than a device path header, then NULL is returned.
   If there is not enough memory to allocate space for the new device path, then NULL is returned.
   The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
   free the memory allocated.

   @param  NodeType                   The device node type for the new device node.
   @param  NodeSubType                The device node sub-type for the new device node.
   @param  NodeLength                 The length of the new device node.

   @return The new device path.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 CreateDeviceNode (
   IN UINT8                           NodeType,
   IN UINT8                           NodeSubType,
   IN UINT16                          NodeLength
   );

 /**
   Determines if a device path is single or multi-instance.

   This function returns TRUE if the device path specified by DevicePath is multi-instance.
   Otherwise, FALSE is returned.
   If DevicePath is NULL or invalid, then FALSE is returned.

   @param  DevicePath                 A pointer to a device path data structure.

   @retval  TRUE                      DevicePath is multi-instance.
   @retval  FALSE                     DevicePath is not multi-instance, or DevicePath is NULL or invalid.

 **/
 BOOLEAN
 EFIAPI
 IsDevicePathMultiInstance (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath
   );

 /**
   Retrieves the device path protocol from a handle.

   This function returns the device path protocol from the handle specified by Handle.  If Handle is
   NULL or Handle does not contain a device path protocol, then NULL is returned.

   @param  Handle                     The handle from which to retrieve the device path protocol.

   @return The device path protocol from the handle specified by Handle.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 DevicePathFromHandle (
   IN EFI_HANDLE                      Handle
   );

 /**
   Allocates a device path for a file and appends it to an existing device path.

   If Device is a valid device handle that contains a device path protocol, then a device path for
   the file specified by FileName  is allocated and appended to the device path associated with the
   handle Device.  The allocated device path is returned.  If Device is NULL or Device is a handle
   that does not support the device path protocol, then a device path containing a single device
   path node for the file specified by FileName is allocated and returned.
   The memory for the new device path is allocated from EFI boot services memory. It is the responsibility
   of the caller to free the memory allocated.

   If FileName is NULL, then ASSERT().
   If FileName is not aligned on a 16-bit boundary, then ASSERT().

   @param  Device                     A pointer to a device handle.  This parameter is optional and
                                      may be NULL.
   @param  FileName                   A pointer to a Null-terminated Unicode string.

   @return The allocated device path.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 FileDevicePath (
   IN EFI_HANDLE                      Device,     OPTIONAL
   IN CONST CHAR16                    *FileName
   );

 /**
   Converts a device path to its text representation.

   @param DevicePath      A Pointer to the device to be converted.
   @param DisplayOnly     If DisplayOnly is TRUE, then the shorter text representation
                          of the display node is used, where applicable. If DisplayOnly
                          is FALSE, then the longer text representation of the display node
                          is used.
   @param AllowShortcuts  If AllowShortcuts is TRUE, then the shortcut forms of text
                          representation for a device node can be used, where applicable.

   @return A pointer to the allocated text representation of the device path or
           NULL if DeviceNode is NULL or there was insufficient memory.

 **/
 CHAR16 *
 EFIAPI
 ConvertDevicePathToText (
   IN CONST EFI_DEVICE_PATH_PROTOCOL   *DevicePath,
   IN BOOLEAN                          DisplayOnly,
   IN BOOLEAN                          AllowShortcuts
   );

 /**
   Converts a device node to its string representation.

   @param DeviceNode        A Pointer to the device node to be converted.
   @param DisplayOnly       If DisplayOnly is TRUE, then the shorter text representation
                            of the display node is used, where applicable. If DisplayOnly
                            is FALSE, then the longer text representation of the display node
                            is used.
   @param AllowShortcuts    If AllowShortcuts is TRUE, then the shortcut forms of text
                            representation for a device node can be used, where applicable.

   @return A pointer to the allocated text representation of the device node or NULL if DeviceNode
           is NULL or there was insufficient memory.

 **/
 CHAR16 *
 EFIAPI
 ConvertDeviceNodeToText (
   IN CONST EFI_DEVICE_PATH_PROTOCOL  *DeviceNode,
   IN BOOLEAN                         DisplayOnly,
   IN BOOLEAN                         AllowShortcuts
   );

 /**
   Convert text to the binary representation of a device node.

   @param TextDeviceNode  TextDeviceNode points to the text representation of a device
                          node. Conversion starts with the first character and continues
                          until the first non-device node character.

   @return A pointer to the EFI device node or NULL if TextDeviceNode is NULL or there was
           insufficient memory or text unsupported.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 ConvertTextToDeviceNode (
   IN CONST CHAR16 *TextDeviceNode
   );

 /**
   Convert text to the binary representation of a device path.

   @param TextDevicePath  TextDevicePath points to the text representation of a device
                          path. Conversion starts with the first character and continues
                          until the first non-device node character.

   @return A pointer to the allocated device path or NULL if TextDeviceNode is NULL or
           there was insufficient memory.

 **/
 EFI_DEVICE_PATH_PROTOCOL *
 EFIAPI
 ConvertTextToDevicePath (
   IN CONST CHAR16 *TextDevicePath
   );

 #endif
	/** @file
	Provides library functions to construct and parse UEFI Device Paths.

	This library provides defines, macros, and functions to help create and parse
	EFI_DEVICE_PATH_PROTOCOL structures.

	Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
	This program and the accompanying materials are licensed and made available under
	the terms and conditions of the BSD License that accompanies this distribution.
	The full text of the license may be found at
	http://opensource.org/licenses/bsd-license.php.

	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

	**/

	#ifndef __DEVICE_PATH_LIB_H__
	#define __DEVICE_PATH_LIB_H__

	#define END_DEVICE_PATH_LENGTH (sizeof (EFI_DEVICE_PATH_PROTOCOL))

	/**
	Determine whether a given device path is valid.
	If DevicePath is NULL, then ASSERT().

	@param DevicePath A pointer to a device path data structure.
	@param MaxSize The maximum size of the device path data structure.

	@retval TRUE DevicePath is valid.
	@retval FALSE The length of any node node in the DevicePath is less
	than sizeof (EFI_DEVICE_PATH_PROTOCOL).
	@retval FALSE If MaxSize is not zero, the size of the DevicePath
	exceeds MaxSize.
	@retval FALSE If PcdMaximumDevicePathNodeCount is not zero, the node
	count of the DevicePath exceeds PcdMaximumDevicePathNodeCount.
	**/
	BOOLEAN
	EFIAPI
	IsDevicePathValid (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath,
	IN UINTN MaxSize
	);

	/**
	Returns the Type field of a device path node.

	Returns the Type field of the device path node specified by Node.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	@return The Type field of the device path node specified by Node.

	**/
	UINT8
	EFIAPI
	DevicePathType (
	IN CONST VOID *Node
	);

	/**
	Returns the SubType field of a device path node.

	Returns the SubType field of the device path node specified by Node.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	@return The SubType field of the device path node specified by Node.

	**/
	UINT8
	EFIAPI
	DevicePathSubType (
	IN CONST VOID *Node
	);

	/**
	Returns the 16-bit Length field of a device path node.

	Returns the 16-bit Length field of the device path node specified by Node.
	Node is not required to be aligned on a 16-bit boundary, so it is recommended
	that a function such as ReadUnaligned16() be used to extract the contents of
	the Length field.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	@return The 16-bit Length field of the device path node specified by Node.

	**/
	UINTN
	EFIAPI
	DevicePathNodeLength (
	IN CONST VOID *Node
	);

	/**
	Returns a pointer to the next node in a device path.

	Returns a pointer to the device path node that follows the device path node specified by Node.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	@return a pointer to the device path node that follows the device path node specified by Node.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	NextDevicePathNode (
	IN CONST VOID *Node
	);

	/**
	Determines if a device path node is an end node of a device path.
	This includes nodes that are the end of a device path instance and nodes that
	are the end of an entire device path.

	Determines if the device path node specified by Node is an end node of a device path.
	This includes nodes that are the end of a device path instance and nodes that are the
	end of an entire device path. If Node represents an end node of a device path,
	then TRUE is returned. Otherwise, FALSE is returned.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	@retval TRUE The device path node specified by Node is an end node of a device path.
	@retval FALSE The device path node specified by Node is not an end node of a device path.

	**/
	BOOLEAN
	EFIAPI
	IsDevicePathEndType (
	IN CONST VOID *Node
	);

	/**
	Determines if a device path node is an end node of an entire device path.

	Determines if a device path node specified by Node is an end node of an entire device path.
	If Node represents the end of an entire device path, then TRUE is returned.
	Otherwise, FALSE is returned.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	@retval TRUE The device path node specified by Node is the end of an entire device path.
	@retval FALSE The device path node specified by Node is not the end of an entire device path.

	**/
	BOOLEAN
	EFIAPI
	IsDevicePathEnd (
	IN CONST VOID *Node
	);

	/**
	Determines if a device path node is an end node of a device path instance.

	Determines if a device path node specified by Node is an end node of a device path instance.
	If Node represents the end of a device path instance, then TRUE is returned.
	Otherwise, FALSE is returned.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	@retval TRUE The device path node specified by Node is the end of a device path instance.
	@retval FALSE The device path node specified by Node is not the end of a device path instance.

	**/
	BOOLEAN
	EFIAPI
	IsDevicePathEndInstance (
	IN CONST VOID *Node
	);

	/**
	Sets the length, in bytes, of a device path node.

	Sets the length of the device path node specified by Node to the value specified
	by NodeLength. NodeLength is returned. Node is not required to be aligned on
	a 16-bit boundary, so it is recommended that a function such as WriteUnaligned16()
	be used to set the contents of the Length field.

	If Node is NULL, then ASSERT().
	If NodeLength >= 0x10000, then ASSERT().
	If NodeLength < sizeof (EFI_DEVICE_PATH_PROTOCOL), then ASSERT().

	@param Node A pointer to a device path node data structure.
	@param Length The length, in bytes, of the device path node.

	@return Length

	**/
	UINT16
	EFIAPI
	SetDevicePathNodeLength (
	IN OUT VOID *Node,
	IN UINTN Length
	);

	/**
	Fills in all the fields of a device path node that is the end of an entire device path.

	Fills in all the fields of a device path node specified by Node so Node represents
	the end of an entire device path. The Type field of Node is set to
	END_DEVICE_PATH_TYPE, the SubType field of Node is set to
	END_ENTIRE_DEVICE_PATH_SUBTYPE, and the Length field of Node is set to
	END_DEVICE_PATH_LENGTH. Node is not required to be aligned on a 16-bit boundary,
	so it is recommended that a function such as WriteUnaligned16() be used to set
	the contents of the Length field.

	If Node is NULL, then ASSERT().

	@param Node A pointer to a device path node data structure.

	**/
	VOID
	EFIAPI
	SetDevicePathEndNode (
	OUT VOID *Node
	);

	/**
	Returns the size of a device path in bytes.

	This function returns the size, in bytes, of the device path data structure
	specified by DevicePath including the end of device path node.
	If DevicePath is NULL or invalid, then 0 is returned.

	@param DevicePath A pointer to a device path data structure.

	@retval 0 If DevicePath is NULL or invalid.
	@retval Others The size of a device path in bytes.

	**/
	UINTN
	EFIAPI
	GetDevicePathSize (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath
	);

	/**
	Creates a new copy of an existing device path.

	This function allocates space for a new copy of the device path specified by DevicePath. If
	DevicePath is NULL, then NULL is returned. If the memory is successfully allocated, then the
	contents of DevicePath are copied to the newly allocated buffer, and a pointer to that buffer
	is returned. Otherwise, NULL is returned.
	The memory for the new device path is allocated from EFI boot services memory.
	It is the responsibility of the caller to free the memory allocated.

	@param DevicePath A pointer to a device path data structure.

	@retval NULL DevicePath is NULL or invalid.
	@retval Others A pointer to the duplicated device path.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	DuplicateDevicePath (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath
	);

	/**
	Creates a new device path by appending a second device path to a first device path.

	This function creates a new device path by appending a copy of SecondDevicePath to a copy of
	FirstDevicePath in a newly allocated buffer. Only the end-of-device-path device node from
	SecondDevicePath is retained. The newly created device path is returned.
	If FirstDevicePath is NULL, then it is ignored, and a duplicate of SecondDevicePath is returned.
	If SecondDevicePath is NULL, then it is ignored, and a duplicate of FirstDevicePath is returned.
	If both FirstDevicePath and SecondDevicePath are NULL, then a copy of an end-of-device-path is
	returned.
	If there is not enough memory for the newly allocated buffer, then NULL is returned.
	The memory for the new device path is allocated from EFI boot services memory. It is the
	responsibility of the caller to free the memory allocated.

	@param FirstDevicePath A pointer to a device path data structure.
	@param SecondDevicePath A pointer to a device path data structure.

	@retval NULL If there is not enough memory for the newly allocated buffer.
	@retval NULL If FirstDevicePath or SecondDevicePath is invalid.
	@retval Others A pointer to the new device path if success.
	Or a copy an end-of-device-path if both FirstDevicePath and SecondDevicePath are NULL.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	AppendDevicePath (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *FirstDevicePath, OPTIONAL
	IN CONST EFI_DEVICE_PATH_PROTOCOL *SecondDevicePath OPTIONAL
	);

	/**
	Creates a new path by appending the device node to the device path.

	This function creates a new device path by appending a copy of the device node specified by
	DevicePathNode to a copy of the device path specified by DevicePath in an allocated buffer.
	The end-of-device-path device node is moved after the end of the appended device node.
	If DevicePathNode is NULL then a copy of DevicePath is returned.
	If DevicePath is NULL then a copy of DevicePathNode, followed by an end-of-device path device
	node is returned.
	If both DevicePathNode and DevicePath are NULL then a copy of an end-of-device-path device node
	is returned.
	If there is not enough memory to allocate space for the new device path, then NULL is returned.
	The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
	free the memory allocated.

	@param DevicePath A pointer to a device path data structure.
	@param DevicePathNode A pointer to a single device path node.

	@retval NULL There is not enough memory for the new device path.
	@retval Others A pointer to the new device path if success.
	A copy of DevicePathNode followed by an end-of-device-path node
	if both FirstDevicePath and SecondDevicePath are NULL.
	A copy of an end-of-device-path node if both FirstDevicePath and SecondDevicePath are NULL.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	AppendDevicePathNode (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath, OPTIONAL
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePathNode OPTIONAL
	);

	/**
	Creates a new device path by appending the specified device path instance to the specified device
	path.

	This function creates a new device path by appending a copy of the device path instance specified
	by DevicePathInstance to a copy of the device path secified by DevicePath in a allocated buffer.
	The end-of-device-path device node is moved after the end of the appended device path instance
	and a new end-of-device-path-instance node is inserted between.
	If DevicePath is NULL, then a copy if DevicePathInstance is returned.
	If DevicePathInstance is NULL, then NULL is returned.
	If DevicePath or DevicePathInstance is invalid, then NULL is returned.
	If there is not enough memory to allocate space for the new device path, then NULL is returned.
	The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
	free the memory allocated.

	@param DevicePath A pointer to a device path data structure.
	@param DevicePathInstance A pointer to a device path instance.

	@return A pointer to the new device path.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	AppendDevicePathInstance (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath, OPTIONAL
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePathInstance OPTIONAL
	);

	/**
	Creates a copy of the current device path instance and returns a pointer to the next device path
	instance.

	This function creates a copy of the current device path instance. It also updates DevicePath to
	point to the next device path instance in the device path (or NULL if no more) and updates Size
	to hold the size of the device path instance copy.
	If DevicePath is NULL, then NULL is returned.
	If DevicePath points to a invalid device path, then NULL is returned.
	If there is not enough memory to allocate space for the new device path, then NULL is returned.
	The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
	free the memory allocated.
	If Size is NULL, then ASSERT().

	@param DevicePath On input, this holds the pointer to the current device path
	instance. On output, this holds the pointer to the next device
	path instance or NULL if there are no more device path
	instances in the device path pointer to a device path data
	structure.
	@param Size On output, this holds the size of the device path instance, in
	bytes or zero, if DevicePath is NULL.

	@return A pointer to the current device path instance.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	GetNextDevicePathInstance (
	IN OUT EFI_DEVICE_PATH_PROTOCOL **DevicePath,
	OUT UINTN *Size
	);

	/**
	Creates a device node.

	This function creates a new device node in a newly allocated buffer of size NodeLength and
	initializes the device path node header with NodeType and NodeSubType. The new device path node
	is returned.
	If NodeLength is smaller than a device path header, then NULL is returned.
	If there is not enough memory to allocate space for the new device path, then NULL is returned.
	The memory is allocated from EFI boot services memory. It is the responsibility of the caller to
	free the memory allocated.

	@param NodeType The device node type for the new device node.
	@param NodeSubType The device node sub-type for the new device node.
	@param NodeLength The length of the new device node.

	@return The new device path.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	CreateDeviceNode (
	IN UINT8 NodeType,
	IN UINT8 NodeSubType,
	IN UINT16 NodeLength
	);

	/**
	Determines if a device path is single or multi-instance.

	This function returns TRUE if the device path specified by DevicePath is multi-instance.
	Otherwise, FALSE is returned.
	If DevicePath is NULL or invalid, then FALSE is returned.

	@param DevicePath A pointer to a device path data structure.

	@retval TRUE DevicePath is multi-instance.
	@retval FALSE DevicePath is not multi-instance, or DevicePath is NULL or invalid.

	**/
	BOOLEAN
	EFIAPI
	IsDevicePathMultiInstance (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath
	);

	/**
	Retrieves the device path protocol from a handle.

	This function returns the device path protocol from the handle specified by Handle. If Handle is
	NULL or Handle does not contain a device path protocol, then NULL is returned.

	@param Handle The handle from which to retrieve the device path protocol.

	@return The device path protocol from the handle specified by Handle.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	DevicePathFromHandle (
	IN EFI_HANDLE Handle
	);

	/**
	Allocates a device path for a file and appends it to an existing device path.

	If Device is a valid device handle that contains a device path protocol, then a device path for
	the file specified by FileName is allocated and appended to the device path associated with the
	handle Device. The allocated device path is returned. If Device is NULL or Device is a handle
	that does not support the device path protocol, then a device path containing a single device
	path node for the file specified by FileName is allocated and returned.
	The memory for the new device path is allocated from EFI boot services memory. It is the responsibility
	of the caller to free the memory allocated.

	If FileName is NULL, then ASSERT().
	If FileName is not aligned on a 16-bit boundary, then ASSERT().

	@param Device A pointer to a device handle. This parameter is optional and
	may be NULL.
	@param FileName A pointer to a Null-terminated Unicode string.

	@return The allocated device path.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	FileDevicePath (
	IN EFI_HANDLE Device, OPTIONAL
	IN CONST CHAR16 *FileName
	);

	/**
	Converts a device path to its text representation.

	@param DevicePath A Pointer to the device to be converted.
	@param DisplayOnly If DisplayOnly is TRUE, then the shorter text representation
	of the display node is used, where applicable. If DisplayOnly
	is FALSE, then the longer text representation of the display node
	is used.
	@param AllowShortcuts If AllowShortcuts is TRUE, then the shortcut forms of text
	representation for a device node can be used, where applicable.

	@return A pointer to the allocated text representation of the device path or
	NULL if DeviceNode is NULL or there was insufficient memory.

	**/
	CHAR16 *
	EFIAPI
	ConvertDevicePathToText (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath,
	IN BOOLEAN DisplayOnly,
	IN BOOLEAN AllowShortcuts
	);

	/**
	Converts a device node to its string representation.

	@param DeviceNode A Pointer to the device node to be converted.
	@param DisplayOnly If DisplayOnly is TRUE, then the shorter text representation
	of the display node is used, where applicable. If DisplayOnly
	is FALSE, then the longer text representation of the display node
	is used.
	@param AllowShortcuts If AllowShortcuts is TRUE, then the shortcut forms of text
	representation for a device node can be used, where applicable.

	@return A pointer to the allocated text representation of the device node or NULL if DeviceNode
	is NULL or there was insufficient memory.

	**/
	CHAR16 *
	EFIAPI
	ConvertDeviceNodeToText (
	IN CONST EFI_DEVICE_PATH_PROTOCOL *DeviceNode,
	IN BOOLEAN DisplayOnly,
	IN BOOLEAN AllowShortcuts
	);

	/**
	Convert text to the binary representation of a device node.

	@param TextDeviceNode TextDeviceNode points to the text representation of a device
	node. Conversion starts with the first character and continues
	until the first non-device node character.

	@return A pointer to the EFI device node or NULL if TextDeviceNode is NULL or there was
	insufficient memory or text unsupported.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	ConvertTextToDeviceNode (
	IN CONST CHAR16 *TextDeviceNode
	);

	/**
	Convert text to the binary representation of a device path.

	@param TextDevicePath TextDevicePath points to the text representation of a device
	path. Conversion starts with the first character and continues
	until the first non-device node character.

	@return A pointer to the allocated device path or NULL if TextDeviceNode is NULL or
	there was insufficient memory.

	**/
	EFI_DEVICE_PATH_PROTOCOL *
	EFIAPI
	ConvertTextToDevicePath (
	IN CONST CHAR16 *TextDevicePath
	);

	#endif