User`s guide

Macros for Porting from VAX to Alpha or I64

This appendix describes macros that facilitate the porting of VAX MACRO code to

an OpenVMS Alpha or OpenVMS I64 system. The macros are grouped according

to their function:

• Section D.1, Calculating Page-Size Values

• Section D.2, Saving and Restoring 64-Bit Registers

• Section D.3, Locking Pages into a Working Set

Note that you can use certain arguments to the macros described in this appendix

to indicate register sets. To express a register set, list the registers, separated by

commas, within angle brackets. For instance:

<R1,R2,R3>

If the set contains only one register, omit the angle brackets:

D.1 Calculating Page-Size Values

The following macros provide a standard, architecture-independent means for

calculating page-size dependent values:

• $BYTES_TO_PAGES

• $NEXT_PAGE

• $PAGES_TO_BYTES

• $PREVIOUS_PAGE

• $ROUND_RETADR

• $START_OF_PAGE

These macros reside in the directory SYS$LIBRARY:STARLET.MLB and can be

used by both application code and system code. Because application code does

not have access to SYSTEM_DATA_CELLS, you must supply the relevant masks,

shift values, and so on.

The shift values are correlated with the page size of the processor. The rightshift

values are negative; the leftshift values are positive, as shown in Table D–1.

Macros for Porting from VAX to Alpha or I64 D–1