User`s guide

Recommended and Required Source Changes

3.5 Overwriting Static Data

The new data must be completely within the bounds of the previous .ASCII

string. The following is illegal:

DATA: .ascii /abcdefg/

.=data+4

.ascii /lmnop/ ; exceeds end of previous .ASCII

Partial overwriting with other directive types (.LONG, and so forth) is not

allowed.

3.6 Static Initialization Using External Symbols

Some forms of static initialization using external symbols are not allowed.

Recommended Change

Where possible, change your code to one of the forms that is allowed. This

can often be done by deﬁning additional symbols using $xxxDEF macros. On

OpenVMS Alpha and OpenVMS I64 systems, the compiler supports expressions

of the form:

where OPR can be:

+ Add

- Subtract

* Multiply

/ Divide

@ Arithmetic shift

& Logical inclusive AND

! Logical inclusive OR

\ Logical exclusive OR

Symbol1 and symbol2 (both optional) are external values or labels in another

psect, and offset1 and offset2 can be expressions but must resolve to compile-

time constants.

On OpenVMS I64 systems, due to the design of the ELF object ﬁle format, the

linker will only allow subtraction when symbol1 or symbol2 resolves to the

address of a routine.

The compiler does not support expressions of the form:

If a static initialization expression cannot be reduced to this form, the compiler

will report an illegal static initialization. Use brackets to ensure correct operator

precedence.

3.7 Transfer Vectors

The compiler ﬂags any occurrence of the .TRANSFER directive in VAX MACRO

code as an error unless you have speciﬁed /noﬂag=directives. In that case, no

message is reported, but the .TRANSFER directive is ignored.

On OpenVMS VAX systems, you can establish universal entry points for

relocatable code in shareable images by explicitly deﬁning transfer vectors in

VAX MACRO source code. On OpenVMS Alpha and OpenVMS I64 systems,

you establish them by declaring the symbol values of universal entry points

in a linker options ﬁle. The linker constructs a symbol vector table within

3–16 Recommended and Required Source Changes