FILE OPEN

Op-Code:	PXENV_FILE_OPEN (00e0h)

Input:		Far pointer to a t_PXENV_FILE_OPEN parameter structure
		that has been initialised by the caller.

Output:		PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be
		returned in AX.  The status field in the parameter
		structure must be set to one of the values represented
		by the PXENV_STATUS_xxx constants.

Description:	Opens a file specified by a URL for reading.  Multiple
		files may be opened and used concurrently.


typedef struct s_PXENV_FILE_OPEN {
	PXENV_STATUS Status;
	UINT16 FileHandle;
	SEGOFF16 FileName;
	UINT32 Reserved;
} t_PXENV_FILE_OPEN;


Set before calling API service:

FileName:	URL of file to be opened.  Null terminated.

Reserved:	Must be zero.


Returned from API service:

FileHandle:	Handle for use in subsequent PXE FILE API calls.

Status:		See PXENV_STATUS_xxx constants.




FILE CLOSE

Op-Code:	PXENV_FILE_CLOSE (00e1h)

Input:		Far pointer to a t_PXENV_FILE_CLOSE parameter structure
		that has been initialised by the caller.

Output:		PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be
		returned in AX.  The status field in the parameter
		structure must be set to one of the values represented
		by the PXENV_STATUS_xxx constants.

Description:	Closes a previously opened file.


typedef struct s_PXENV_FILE_CLOSE {
	PXENV_STATUS Status;
	UINT16 FileHandle;
} t_PXENV_FILE_CLOSE;


Set before calling API service:

FileHandle:	Handle obtained when file was opened.


Returned from API service:

Status:		See PXENV_STATUS_xxx constants.




FILE SELECT

Op-Code:	PXENV_FILE_SELECT (00e2h)

Input:		Far pointer to a t_PXENV_FILE_SELECT parameter structure
		that has been initialised by the caller.

Output:		PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be
		returned in AX.  The status field in the parameter
		structure must be set to one of the values represented
		by the PXENV_STATUS_xxx constants.

Description:	Check a previously opened file's readiness for I/O.


typedef struct s_PXENV_FILE_SELECT {
	PXENV_STATUS Status;
	UINT16 FileHandle;
	UINT16 Ready;
#define RDY_READ 0x0001
} t_PXENV_FILE_SELECT;


Set before calling API service:

FileHandle:	Handle obtained when file was opened.


Returned from API service:

Ready:		Indication of readiness.  This can be zero, or more,
		of the RDY_xxx constants.  Multiple values are
		arithmetically or-ed together.

Status:		See PXENV_STATUS_xxx constants.




FILE READ

Op-Code:	PXENV_FILE_READ (00e3h)

Input:		Far pointer to a t_PXENV_FILE_READ parameter structure
		that has been initialised by the caller.

Output:		PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be
		returned in AX.  The status field in the parameter
		structure must be set to one of the values represented
		by the PXENV_STATUS_xxx constants.

		This API function is non-blocking.  PXENV_EXIT_SUCCESS
		and PXENV_STATUS_SUCCESS is returned if a data block
		has been transferred into the caller's buffer.
		PXENV_EXIT_FAILURE and PXENV_STATUS_TFTP_OPEN is
		returned if no data is available to transfer; any
		other status code reflects an error.

Description:	Read from a previously opened file.


typedef struct s_PXENV_FILE_READ {
	PXENV_STATUS Status;
	UINT16 FileHandle;
	UINT16 BufferSize;
	SEGOFF16 Buffer;
} t_PXENV_FILE_READ;


Set before calling API service:

FileHandle:	Handle obtained when file was opened.

BufferSize:	Maximum number of data bytes that can be copied into
		Buffer.

Buffer:		Segment:Offset address of data buffer.


Returned from API service:

BufferSize:	Number of bytes written to the data buffer.  End of
		file if this is zero.

Status:		See PXENV_STATUS_xxx constants.




GET FILE SIZE

Op-Code:	PXENV_GET_FILE_SIZE (00e4h)

Input:		Far pointer to a t_PXENV_GET_FILE_SIZE parameter
		structure that has been initialised by the caller.

Output:		PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be
		returned in AX.  The status field in the parameter
		structure must be set to one of the values represented
		by the PXENV_STATUS_xxx constants.

Description:	Determine size of a previously opened file.


typedef struct s_PXENV_GET_FILE_SIZE {
	PXENV_STATUS Status;
	UINT16 FileHandle;
	UINT32 FileSize;
} t_PXENV_GET_FILE_SIZE;


Set before calling API service:

FileHandle:	Handle obtained when file was opened.


Returned from API service:

FileSize:	Size of the file in bytes.

Status:		See PXENV_STATUS_xxx constants.




FILE EXEC

Op-Code:	PXENV_FILE_EXEC (00e5h)

Input:		Far pointer to a t_PXENV_FILE_EXEC parameter
		structure that has been initialized by the caller.

Output:		PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be
		returned in AX.  The Status field in the parameter
		structure must be set to one of the values represented
		by the PXENV_STATUS_xxx constants.

Description:	Execute a gPXE command.

typedef struct s_PXENV_FILE_EXEC {
        PXENV_STATUS_t Status;
        SEGOFF16_t Command;
} t_PXENV_FILE_EXEC;


Set before calling API service:

Command:	Command to execute.  Null terminated.


Returned from API service:

Status:		See PXENV_STATUS_xxx constants.




FILE API CHECK

Op-Code:	PXENV_FILE_API_CHECK (00e6h)

Input:		Far pointer to a t_PXENV_FILE_CHECK_API parameter
		structure that has been initialized by the caller.

		On entry, the Magic field should contain the number
		0x91d447b2 or the call will fail.

Output:		PXENV_EXIT_SUCCESS or PXENV_EXIT_FAILURE must be
		returned in AX.  The Status field in the parameter
		structure must be set to one of the values represented
		by the PXENV_STATUS_xxx constants.

		If this API is present and the Magic field contains the
		proper value on entry, AX will contain PXENV_EXIT_SUCCESS,
		the Status field PXENV_STATUS_SUCCESS, and the Magic field
		the number 0xe9c17b20.  Any other combination should be
		considered a failure.

Description:	Detect presence of this API.


typedef struct s_PXENV_FILE_CHECK_API {
	PXENV_STATUS Status;
	UINT16 Size;
	UINT32 Magic;
	UINT32 Provider;
	UINT32 APIMask;
	UINT32 Flags;
} t_PXENV_FILE_CHECK_API;

Set before calling API service:

Size:		Set to sizeof(t_PXENV_FILE_CHECK_API) (20).
Magic:		Set to 0x91d447b2.


Returned from API service:

Size:		Set to the number of bytes filled in (20).
Magic:		Set to 0xe9c17b20.
Provider:	Set to 0x45585067 ("gPXE").  Another implementation of this
		API can use another value, e.g. to indicate a different
		command set supported by FILE EXEC.
APIMask:	Bitmask of supported API functions (one bit for each function
		in the range 00e0h to 00ffh).
Flags:		Set to zero, reserved for future use.
