PAM Programming Manual

Link-Level Interfaces
PAM Programming Manual—142482
3-25
Formatting an SDU Header (Token Ring)
The SDU type ZLATR^VAL^SDUTYPE^LLC2 is not supported for file-system
applications. The results are unpredictable if a file-system application attempts to
use LLC2 aggregate types.
SDU^User^Data^Offset^B (INT .EXT)
Conditional output returns the byte offset from the beginning of the aggregate SDU
buffer where the application should begin placing data associated with an outbound
SDU. If the SDU^User^Data^Size^B parameter is passed and is nonzero, then this
parameter must be passed; otherwise it is not required.
SDU^User^Data^Size^B (INT)
Optional input that declares how many bytes of user data the application wants to
put in the user data portion of the SDU. If no user data is to be added to the SDU,
then this parameter does not need to be included.
The syntax for C programs is
Formatting an SDU Header (Token Ring)
This primitive formats an individual SDU header within a previously created aggregate
SDU buffer. The SDU header begins at the first word boundary after the aggregate SDU
header, or the first word boundary after the preceding SDU header, if any. This primitive
passes back to the application a byte offset from the beginning of the aggregate SDU
buffer indicating where the user data, if any, begins.
The syntax for this primitive is
The parameters for this primitive are defined as follows:
AggrSDU^Buff^ptr (STRING .EXT)
Required input used to reference the buffer to be used for the aggregate SDU to the
L2TR Formatting Library.
short ZL2TR_FRMT_AGGR_SDU_N_SDU_HDR_
( char *Ag_SDU_Buff_Ptr
,short Ag_SDU_Buff_Size_B
,short Sdu_Type
,short Sap_Val
,char *Mac_Frame
,long Mux_Id
,short *SDU_User_Data_Offset_B
,short SDU_User_Data_Size_B )
INT PROC ZL2TR^Frmt^SDU^Hdr^
( AggrSDU^Buff^ptr
,mac^frame
,mux^id
,SDU^User^Data^Offset^B
,SDU^User^Data^Size^B ) EXTENSIBLE;