pTAL Guidelines for TAL Programmers

Differences Between TAL and pTAL
pTAL Guidelines for TAL Programmers—527256-002
3-11
Declaring Procedure Pointer Variables
For most situations, you can use the .SGX indirection symbol. You might need
to use the .SG indirection symbol if you use CISC instructions that require that
pointers to system data be 16 bits (for example, time list instructions).
identifier
is a standard pTAL identifier
referral
is the name of a previously declared structure or structure pointer. You must
include referral if the formal parameter identifier is the name of a
structure.
Declaring Procedure Pointer Variables
Declare procedure pointer variables, including equivalenced variables, using the
following syntax:
procptr
is a procedure pointer declaration as previously defined in this section.
prev-identifier
is the identifier of a previously declared procedure pointer (PROCPTR) or
procedure address (PROCADDR). For a TNS process, prev-identifier must
be 16 bits. For a native process, prev-identifier must be 32 bits or more.
procaddr
is a constant or dynamic expression of type PROCADDR. procaddr must be the
name of a procedure, procedure pointer, or PROCADDR variable. If procaddr is
a procedure or procedure pointer, the parameters of procptr and procaddr
must match and the following procedure attributes must match: EXTENSIBLE,
VARIABLE, RETURNSCC, MAIN, and INTERRUPT; the following procedure
attributes do not have to match: OVERFLOW_TRAPS, CALLABLE, PRIV, and
RESIDENT.
;
VST714.vsd
=
:=
prev-identifier
procaddr
procptr