PAM Programming Manual

Link-Level Interfaces
PAM Programming Manual—142482
3-24
Formatting an Aggregate SDU and an SDU Header
(Token Ring)
The LLC1 SDU header formatted by this L2TR primitive is described in the
ZL2TR^Frmt^SDU^Hdr^ primitive that follows.
The aggregate SDU header begins at the first word of the aggregate SDU buffer,
followed directly by the initial SDU header. This primitive passes back to the
application an offset, in bytes, from the beginning of the aggregate SDU buffer to the
location where the user data 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.
Aggr^SDU^Buff^Size^B (INT)
Required input that tells the L2TR Formatting Library the size, in bytes, of the
buffer to be used for the aggregate SDU.
sdu^type (INT)
Required input that is used to determine what type of SDU header to generate.
ZL2TR^VAL^SDUTYPE^LLC1 is the currently defined value for this parameter.
sap^value (INT)
Required input that should be the SAP value from a previously opened SAP. The
value must be even and nonzero. The value %H3E is reserved.
mac^frame (STRING .EXT)
For LLC1 frames, this required input points to an array of bytes that are formatted
by the mac^frame structure.
mux^id (INT(32))
For LLC2 type aggregates, this input indicates the mux^id of the session.
Note. You cannot mix different SDU types in an aggregate SDU.
INT PROC ZL2TR^Frmt^Aggr^SDU^n^SDU^Hdr^
( AggrSDU^Buff^ptr,
,Aggr^SDU^Buff^Size^B
,sdu^type
,sap^value
,mac^frame
,mux^id
,SDU^User^Data^Offset^B
,SDU^User^Data^Size^B ) EXTENSIBLE;