RE: camonitor and caget - displaying unsigned longs in hexadecimal

["Allison, Stephanie" <saa@slac.stanford.edu>]

Hi Andrew,

Thanks for the detailed explanation.  Unfortunately, camonitor doesn't
support the -d option (and I'd really like to see hex from camonitor).
This should be something possible with some code modification, I think.

Thanks again,
Stephanie

> -----Original Message-----
> From: Andrew Johnson [mailto:anj@aps.anl.gov]
> Sent: Friday, December 04, 2009 3:55 PM
> To: tech-talk@aps.anl.gov
> Cc: Allison, Stephanie
> Subject: Re: camonitor and caget - displaying unsigned longs in
hexadecimal
> 
> Hi Stephanie,
> 
> On Friday 04 December 2009 17:16:34 Allison, Stephanie wrote:
> >
> > I notice that camonitor and caget do not honor the "-0x" option
(option
> > to printout as hex) for PVs that are unsigned long's.  Such PVs are
sent
> > over CA as double's and -0x is not available for doubles, per
design.
> > Are there other options that I could use instead?    Should I look
into
> > changing the tools to allow for -0x for unsigned long's?
> 
> CA can't transport unsigned types as such, although the IOC database
supports
> them.  If you do a cainfo of one of your ULONG PVs you'll see that its
native
> type actually gets reported as a DBF_DOUBLE, which is the smallest
type that
> CA can guarantee will pass any ULONG value correctly.  Unfortunately
CA gives
> no indication of what the real database type is, so I don't think the
tool
> could properly detect that the field is really a ULONG.
> 
> However if you ask caget or camonitor to use DBR_LONG when fetching
the value
> (add the switch -d LONG) then it does honor the -0x switch, but the
display
> format is different.  Also if your client is a 64 bit machine you
might get
> the sign bit extended for display.  This is the output I get on
linux-x86_64
> when the top bit is set (note that the DBF_LONG and DBR_LONG types are
only 32
> bits wide even on 64-bit architectures):
> 
> tux% caget -d LONG -0x anjHost:compressExample.N
> anjHost:compressExample.N
>     Native data type: DBF_DOUBLE
>     Request type:     DBR_LONG
>     Element count:    1
>     Value:            0xFFFFFFFF80000000
> 
> HTH, HANW,
> 
> - Andrew
> --
> The best FOSS code is written to be read by other humans -- Harald
Welte