[Info-vax] VAX VMS going forward

[Craig A. Berry]

On 8/1/20 4:34 AM, John Dallman wrote:
> In article <rg123i$8hq$1 at dont-email.me>, craigberry at nospam.mac.com (Craig
> A. Berry) wrote:
> 
>> Actually, it's only code written for VMS using native 64-bit
>> interfaces that is likely to work with 64-bit pointers. Portable
>> code would have to live without the following from table 1-8 of
>> the CRTL manual:
>>
>> atexit         frexp           ioctl           setbuf
>> execv          getopt          modf            setstate
>> execve         iconv           putenv          setvbuf
>> execvp         initstate
>>
>> The problem is not the length of the list but what's on it.  It's
>> hard to imagine a full-featured, portable program that does not
>> use getopt, the exec family of functions, and ioctl.
>>
>> In the case of the OP, a math library might be ok, but the user of
>> that library who wants to write a program would have some hoops to
>> jump through.
> 
> The math library is OK with these, but its test harness needs a few of
> them. However, they all have wrapper functions, to allow for platform-
> specific handling.
> 
> What hoops does one have to jump through? Are there ways to allocate
> memory in P0 or P1, and then obtain short pointers to it for passing to
> the OS?

You have to control the pointer size of the relevant sections of code 
with #pragma pointer_size.  Documentation appears to be scattered among 
the compiler docs, the CRTL docs, the programming concepts manual, and 
the guide to 64-bit addressing.  Here's an old Digital Technical Journal 
article with some of the background:

<https://pdfs.semanticscholar.org/8d96/bbba019c43e80f059825311b67c975a0fede.pdf>