Re: Trying to port libffi to OpenVMS.

["John E. Malmberg" <wb8tyw@qsl.net>]

On 2/13/2015 8:41 AM, Richard Henderson wrote:
> On 02/13/2015 06:00 AM, John E. Malmberg wrote:
>> I was able to apply Philippe Vouters patches for Libffi 3.0.9 to libffi 3.1 and
>> get the code building.  I was unable to get the tests to run under GNV though.
>
> I've never seen those patches but...

Not sure if I got them via E-mail from someone else, or from his site. 
His site is not responding at this time.

The readme says that they include HP-UX/ia64 and VMS/Alpha and VMS/ia64. 
  What I have appears to be bunch of concatenated unified diffs.  I can 
gzip it and forward it to anyone that is interested, uncompressed it is 
126 KB.

>> I am now trying to build master from a git checkout, and have gotten lost with
>> the changes to src/alpha/ffi.c since then, so I am looking for some guidance on
>> how to get libffi from master building.
>
> ... I know that the ABI for vms is significantly different from unix.
> I'd be surprised if the patches were small.

I think VMS and Tru64 share a calling standard on Alpha, but I am not 
sure.  VMS on Itanium uses ELF binaries and calling standard with a few 
extensions to ELF.

In any case, on VMS, the "int lib$callg(void **args, int (*func)())" 
hides all that though.

> I don't know that there's a wiki, per se...

That is what the text at that web site says.  It actually implies that 
it is posted on a WIKI.

What I should have done is read the libffi online manual instead of 
trying just to understand what Philippe did.

The use of the lib$callg() routine means I should not need any assembly 
language code at all.  Probably almost the same source for all three 
current VMS harware platforms.

Thanks for the reply.

Regards,
-John