TAL Reference Manual

Privileged Procedures
TAL Reference Manual—526371-001
15-7
Usage Considerations
. (period)
is the standard indirection symbol and denotes 16-bit addressing, in this case in
the system global data area.
.SG
is the system global indirection symbol and denotes 16-bit addressing in the
system global data area.
.EXT
is the extended indirection symbol and denotes 32-bit addressing.
identifier
is the identifier of a referral structure to be made equivalent to 'SG'.
referral
is the identifier of a previously declared structure or structure pointer that is to
provide the layout for this structure.
'SG'
is the symbol that denotes the base address of the system global data area;
identifier is addressed relative to SG[0].
index and offset
are equivalent INT values in the range 0 through 63.
Usage Considerations
If you specify an indirection symbol (., .SG, or .EXT), the structure behaves like a
structure pointer. If you do not specify an indirection symbol, the structure has direct
addressing mode.
Example of 'SG'-Equivalenced Referral Structure
This example declares a referral structure equivalent to location SG[30] in the system
global data area:
STRUCT def_struct;
BEGIN
STRING a[0:99];
REAL b[0:9];
END;
STRUCT ref_struct (def_struct) = 'SG'[30];