HP Data Entry and Forms Management System (VPLUS) Reference Manual (32209-90024)

624 AppendixJ
HP PRECISION ARCHITECTURE
MIGRATION ISSUES
MIGRATION ISSUES
Programs that were originally developed on MPE/V must be rewritten to run in native
mode on the MPE/XL. For details, refer to the following reference manuals:
•
Migration Process Guide describes how to migrate existing applications to MPE/XL.
•
Programmers' Skills Migration Guide explains new program development on
MPE/XL and serves as a reference to the operating system.
•
COBOL II/XL Migration Guide explains how to migrate COBOL II/V programs to
MPE/XL.
•
FORTRAN 77/XL Migration Guide, details the migration of FORTRAN 77/V
applications to MPE/XL.
•
HP Pascal/XL Migration Guide details the migration of Pascal applications to
MPE/XL. Migration of SPL programs to MPE/XL.
Some points to be noted when applications developed on VPLUS are run MPE/XL are
described below.
Terminals. When you run an application on MPE/XL, the terminal must be configured for
the XON/XOFF handshake. If it is not, large or complex forms will appear to be corrupted
when displayed on the screen.
Floating Point Numbers. The type conversion of floating point numbers in VPLUS
assumes the HP 3000 floating point format, whereas native mode applications store
floating point values in IEEE format. The type conversion will work, but the values will be
wrong.
Native Mode Pascal Applications. The MPE/XL native mode Pascal compiler allocates
4 bytes for the integer subrange -32768..32767, compared with the 2 bytes allocated by the
MPE/V pascal compiler. You should use type SHORTINT in native mode Pascal applications
to get a 2-byte allocation for this subrange.
Record padding in native mode Pascal will cause data misalignment problems for
programmers using the VPLUS intrinsics, VGETFIELDINFO, VGETFORMINFO, and
VGETFILEIINFO. The problem can be avoided by packing the
inforbuf records passed as
parameters.
Incorrect Parameters. Existing VPLUS applications written in COBOL and recompiled
into MPE/XL native mode may fail to function. The application either fails with VPLUS
error code of 998 or 999, or it aborts with a Memory Fault error. The reason for this is that
the programmer has coded the application to pass a display numeric data type as the
parameter for a VPLUS intrinsic, instead of a binary numeric data type. That is, COBOL
data type PIC 9 has been coded instead of PIC 9 COMP.
This kind of mistake is not caught when the application is compiled, because most COBOL
VPLUS applications do not use the compiler intrinsic mechanism, "CALL
INTRINSIC…USING…". So, the error must be caught at run-time, if at all. It is possible
for the defective program to appear to work correctly in MPE/V and MPE/XL compatibility
mode, because VPLUS is more forgiving when parameters of the wrong type are passed to
it. However, native mode applications on MPE/XL call the VPLUS intrinsics through