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Preparing to Port Macro-32 Code

1.7 Maintaining Common Sources

• One is compiled with the VAX MACRO source code on an Itanium processor

If you choose to make code in a common source module conditional on architecture

type, include ARCH_DEFS.MAR on the command line in your assembly and

compilation and use .IF DF VAX or .IF DF ALPHA or .IF DF IA64.

A code pattern to avoid, and, in fact, to search for and change in already ported

code, is the use of the following:

.IF DF VAX

. . . ; VAX code

.IFF

. . . ; Alpha code

. . . ; will it work for IA64

.ENDC

or, worse:

.IF DF ALPHA

. . . ; Alpha code

.IFF

. . . ; VAX code, will likely fail for IA64

.ENDC

The best code would be:

.IF DF VAX

. . . ; VAX code

.IFF

.IF DF ALPHA

. . . ; Alpha code

.IFF

.IF DF IA64

. . . ; IA64 code

.IFF

.ERROR . . .

.ENDC

An ARCH_DEFS.MAR ﬁle is provided with OpenVMS Alpha and OpenVMS I64.

You need to create a corresponding ﬁle for OpenVMS VAX. The following is an

example of such a ﬁle:

; This is the VAX version of ARCH_DEFS.MAR, which contains

; architectural definitions for compiling sources for

; VAX systems.

;

VAX = 1

VAXPAGE = 1

ADDRESSBITS = 32

The Alpha version exists in SYS$LIBRARY and contains deﬁnitions for the

following symbols:

• ALPHA—to indicate the source code is Alpha architecture-speciﬁc

• BIGPAGE—to indicate the source code assumes variable memory page size

The I64 version exists in SYS$LIBRARY and contains a deﬁnition for the

following symbol:

• IA64—to indicate the source code is Itanium architecture-speciﬁc

1–10 Preparing to Port Macro-32 Code