H-Series Application Migration Guide (H06.03+)

pTAL Migration Tasks

H-Series Application Migration Guide—429855-006

7-4

Using PLATFORM and AUTO Alignment

The PLATFORM directive causes the pTAL compiler to use the same data alignment

as other compilers on the same platform. That alignment might differ from the

alignment produced by the same compiler on a different platform. The AUTO directive

allows the compiler to determine data alignment based on what is most efficient. AUTO

alignment is not guaranteed to be the same on different platforms or for different

compilers on the same platform, and programs should not assume that PLATFORM

and AUTO alignments are the same. Therefore, TNS/R and TNS/E pTAL programs

that share data should not use PLATFORM or AUTO alignment. They should instead

use the SHARED2 and SHARED8 directives as appropriate.

In addition, AUTO alignment should be used only by programs that are not dependent

on any particular data alignment. If a program contains logic that is dependent on a

particular data alignment, use the SHARED2, SHARED8, and PLATFORM directives

as appropriate.

Using RETURN/RETURNSCC in Mixed

Language Programs

This topic applies to pTAL procedures that do all of the following:

•

Return a traditional function value by means of the RETURN statement.

•

Return an unrelated condition code value by means of the RETURNSCC attribute.

•

Are called by C or C++ procedures.

On the TNS platform, a TAL procedure can return both a traditional function value and

an unrelated condition code value. Both return values are accessible after the

procedure call. pTAL procedures emulate this behavior on both the TNS/R and TNS/E

platforms, but C and C++ procedures do not.

On the TNS/R platform, if a C or C++ procedure calls a pTAL procedure that returns

both a traditional function value and a condition code value, the C or C++ compiler

issues an error message.

It is possible to work around this C/C++ compile-time error by writing C/C++ prototypes

that rely on the knowledge that on the TNS/R platform, pTAL object code stores the

two return values as a single concatenated 64-bit value. After the C/C++ procedure

calls the pTAL procedure, it extracts from the 64-bit container either both return values

or only the traditional function value.

These C and C++ prototypes are not guaranteed to work on the TNS/R platform, and

extracting only the traditional function value does not work on the TNS/E platform.

The TNS/E pTAL compiler issues a warning whenever a pTAL procedure returns both

a traditional function value and a condition code value. To migrate such a procedure to

TNS/E, HP recommends that you: