TAL Programmer's Guide

Declaring and Calling Subprocedures
Using Procedures
096254 Tandem Computers Incorporated 11–15
Declaring and Calling
Subprocedures
To declare a subprocedure in its simplest form, specify:
The keyword SUBPROC
The identifier of the subprocedure, followed by a semicolon
A subprocedure body—a BEGIN-END construct that can contain sublocal data
declarations and statements
The following example declares MY_SUBPROC within MY_PROC. A CALL statement
in MY_PROC then calls MY_SUBPROC:
PROC my_proc; !Declare MY_PROC
BEGIN
!Declare local data here
SUBPROC my_subproc; !Declare MY_SUBPROC
BEGIN
!Declare sublocal data here
!Specify sublocal statements here
END; !End MY_SUBPROC
!Specify local statements here
CALL my_subproc; !Call MY_SUBPROC
END; !End MY_PROC
You can declare FORWARD, VARIABLE, or function subprocedures in the same way
as described for procedures (but inside a procedure).
Including Formal
Parameters
Subprocedures have a 32-word storage area for all sublocal data including variables,
temporary results, parameters, and parameter mask if any. In the following example,
MAIN_PROC contains subprocedures SUB1 and SUB2. MAIN_PROC calls SUB2.
SUB2 calls SUB1 and passes parameters to it:
PROC main_proc MAIN; !Declare MAIN_PROC
BEGIN
INT c := 0;
SUBPROC sub1 (param1); !Declare SUB1
INT param1; !Declare formal parameter
BEGIN
INT a := 5;
INT b := 2;
param1 := a + b + c;
END; !End of SUB1
SUBPROC sub2; !Declare SUB2
BEGIN
INT var := 89;
CALL sub1 (var); !Call SUB1
END; !End of SUB2
CALL sub2;
END; !End of MAIN_PROC