PAM Programming Manual

Link-Level Interfaces
PAM Programming Manual—142482
3-7
Formatting an Aggregate SDU Header (Ethernet)
primitive initializes an aggregate SDU buffer, formats the aggregate SDU header, and
formats an initial individual SDU header. Subsequent SDU headers formatted with the
ZL2S^Frmt^SDU^Hdr^ primitive must be passed only aggregate SDU buffers that have
already been initialized by one of the two preceding primitives; otherwise unpredictable
results can occur.
Formatting an Aggregate SDU Header (Ethernet)
Aggregate SDUs are created when the application determines that it needs to send one
or more SDUs to an LSAP and there is no aggregate SDU waiting to be sent to that
LSAP. This primitive initializes an aggregate SDU buffer and formats an aggregate SDU
header.
The syntax for this primitive is
The parameters for this primitive are defined as follows:
Aggr^SDU^Buff^ptr (STRING .EXT)
Required input used to reference the buffer to be used for the aggregate SDU to the
L2S Formatting Library.
Aggr^SDU^Buff^Size^B (INT)
Required input that tells the L2S Formatting Library the size, in bytes, of the buffer
to be used for the aggregate SDU.
The syntax for C programs is:
Aggregate SDU Header Format
The aggregate SDU header formatted by this L2S primitive is defined as follows:
Note. You cannot mix different SDU types in an aggregate SDU.
INT PROC ZL2S^Frmt^Aggr^SDU^Hdr^
( Aggr^SDU^Buff^ptr
,Aggr^SDU^Buff^Size^B) EXTENSIBLE;
short ZL2S_FRMT_AGGR_SDU_HDR_ ( char *Ag_SDU_Buff_Ptr
,short Ag_SDU_Buff_Size_B)
def ZL2S-DDL-Aggr-SDU-Hdr.
02 zWork type ZSPI-DDL-INT.
occurs 2 times.
02 zVsn type ZSPI-DDL-INT.
02 zAddr type ZSPI-DDL-INT.
02 zMAC-Addr type ZSPI-DDL-BYTE.
occurs 6 times.
02 zSDU-Cnt type ZSPI-DDL-INT.
end.