XLF IEEE Handler?

XLF IEEE Handler?

Post by jg » Thu, 11 Apr 1991 07:51:43

I'm just posting this for a friend so please direct
e-mail to the address below


Does anybody know if it is possible to make XLF FORTRAN
on an IBM RS-6000 to trap on a NAN or NANQ (or any other
floating point exception)?

Quote:>From what I can glean in the documentation is that

exception handling can be enabled with:

     call signal(sigtrap,xl_trce)

and an exception will be generated under the following conditions:

a. subscript out of bounds (if you specify the
       CHECK option at compile time)
b. substring out of bounds (if you specify the
       CHECK option at compile time)
c. Fixed point division by zero.
d. Flow of program control reaches a location for
   which a semantic error with severity level S
   was issued when the program was compiled.

Unfortunately these are not any of the conditions I am
interested in (And even if I was this is not particularly
useful since it only produces a traceback through the
offset number of the routine. You then have to map the offset
to the source number by checking the offset on the source listing.).

What I want is something like SUN's ieee_handler that will trap on
the 5 floating point exceptions found in IEEE 754-1985:

     1. invalid opertion
     2. division by zero
     3. overflow
     4. underflow
     5. inexact

Have I missed something in the documentation or isn't this
implemented on the RS-6000?

Joel Rhodes
591 Park Ave. Suite 302
Idaho Falls ID. 83402
ph(208) 522-8443


1. Handlers, Handlers, Handlers

After setting up a structure of handlers to move authorization from Basic to
cgi, it seems that no matter what approach I take, I cannot get the client
to the originally requested uri after authorization.  I can dump content
from the handler, but cannot redirect, internal_redirect, etc.

This, I might add, is further complicated by embedding session ids into the
uri which I began extracting with a RewriteRule in httpd.conf and setting in
the ENV.  But later I let them go through to the Access handler which
extracts the session id (if present) and sets the value in $r->notes (for
availability to subsequent handlers) and resets $r->uri with the new
sessionless URI and DECLINES to Authen.  Authen, in turn, attempts to
validate the session and does and internal_redirect to /login upon failure.
/login is controlled by a content handler to prompt for username/password
and also creates a new session upon authorization.  Invalid credentials
result in an appropriate error message and the login prompt.  All is well up
to this point.  Once credentials have been validated, I've not been able to
display the requested page -- it simply spins until timeout (it rather
sounds like it's stuck in a loop which does nothing continually validates
the session).  BTW, I've also thrown in
return OK unless $r->is_initial_req;  various other attempts at eliminating

Perhaps this should not even be handled by Access and Authen, but by a
single primary content handler on / which extracts session ids and redirects
upon validation, or prompts when invalid.

Thoughts, suggestions????

If you'd like to call, you can reach me here:



Tim Tompkins

Programmer / IS Technician

2. Dailies (was: Re: RTFM?

3. Compatibility between xlf v6 and xlf v7 runtime libraries

4. groff & landscape printing

5. Threads performance - allow signal handler to not call handler

6. Buying a multi-Pentium pro system ... advice requested!!!

7. Piping a Handler to a Handler in apache 1.3.0, i.e., ssi in cgi output

8. partition questions???

9. Mail Handler (or message handler)

10. exec in SIGALARM handler, no new SIGALARM handler??

11. add_timer handler and dev_add_pack handler contexts?

12. Signal handlers inside signal handlers

13. xlf 2.1 under AIX 3.1.5 for RS/6000-540 and SPEC numbers