SPI Programming Manual (G06.24+, H06.03+, J06.03+)

Summary of DDL for SPI
SPI Programming Manual—427506-006
B-5
FILLER Clause
FILLER Clause
A clause beginning with the keyword FILLER specifies an unnamed place-holder field.
The definition files include FILLER clauses where needed to ensure alignment of
adjacent fields on word boundaries. Example 4 in Figure B-1
illustrates the use of the
FILLER clause.
SPI-NULL Clause
When an SPI-NULL clause appears in a DEF or a field of a DEF, it specifies the null
value to be assigned to a variable or structure field based on that DEF when a program
calls the SSNULL procedure. Example 1 in Figure B-1
directs SSNULL to assign a
blank to each byte of each field of a structure defined as type ZSPI-DDL-BOOLEAN.
The second example directs SSNULL to assign the byte value 255 (all binary ones) to
each byte of each field of a structure defined as type ZSPI-DDL-ENUM.
An SPI-NULL clause specified in a group DEF is inherited by each of the fields within
the group. When you reference one DEF from another, any SPI-NULL clauses in the
referring DEF override corresponding SPI-NULL clauses in the referenced DEF.
If a field has no SPI-NULL clause, SSNULL assigns 255 to that field.
TACL Clause
When a TACL clause appears in a DEF or a field of a DEF, it names one of the high-
level TACL data types that can be used in simple data-item declarations within TACL
STRUCT statements. The DDL compiler then translates that field or structure into a
STRUCT field of the corresponding type. Examples of high-level TACL data types that
can appear in the TACL clause are ENUM, CRTPID, DEVICE, and SSID; Section 8
gives the complete list.
If a DEF or field includes a TACL clause but also refers to another DEF that itself
includes a TACL clause, the TACL clause in the higher level DEF overrides the clause
in the referenced DEF.
Example 2 in Figure B-1
directs DDL, when producing TACL output, to translate the
definition ZSPI-DDL-ENUM, or any field defined by reference to ZSPI-DDL-ENUM, to a
simple data item field of type ENUM.
SSID Clause
This DDL clause identifies the subsystem associated with a token code or token map.
When the template compiler compiles the template source file for a subsystem, it
copies the token information from the DDL dictionary to templates if the token code or
token map contains an SSID clause that refers to the subsystem. Without SSID, the
template compiler and the SPI_BUFFER_FORMAT procedures lose access to token
names and to other DDL clauses, limiting the display text they produce.