I got a slightly different result:
pipe literal FFFF 00FFFF | spec w1 x2d 1 w2 x2d nw | cons
-1 65535
I believe that -1 is the correct value if the high order bit is treated
as a sign. -127 is really astonishing.
You can always contrive to have at least 1 high-order 0. X2D does not
display the leading zeros, so it is safe to do.
I found precious little in the documentation for X2D. For B2D, it is
documented that the source is treated as a signed (two's complement)
binary number.
Regards,
Richard Schuh
> -----Original Message-----
> From: CMSTSO Pipelines Discussion List
> [mailto:[EMAIL PROTECTED] On Behalf Of Mike Walter
> Sent: Wednesday, October 29, 2008 3:32 PM
> To: [email protected]
> Subject: SPECS X2D vs astonishment factor
>
> The search
> http://vm.marist.edu/htbin/wlvindex?cmspip-l#search isn't
> turning up anything (and I mean ANYTHING!)... looks broken.
>
> Maybe I'm just having a bad day (probably), or maybe the doc
> is a little weak (maybe).
>
> In a stream of records with real device addresses (the usual hex, from
> 0000-FFFF) in them. I'd like to select those within a certain range.
> The records (from a CP directory) look like (where vdev and
> rdev are the hex address within the 0000 to FFFF range):
>
> _userid_ DEDICATE vdev rdev
>
> I was using:
> ...
> '| SPECS W1.3 1 PAD 0 W4 NW.4 RIGHT' , /* Ensure 4-digit hex
> number for
> X2D */
> '| SPECS W1.4 1 W4 X2D NW' , /* Convert rdev to decimal for
> compare */
> '| PICK W4 >==' loDevNum ,
> '| PICK W4 <==' hiDevNum ,'
> ...
>
> That X2D conversion works "as expected" in rexx. E.g. FFFF =
> 65535 But with SPECS X2D, FFFF = -127 Obviously, it's
> respecting the high order bit.
> High astonishment factor. Makes me wonder what older pipes
> I've written using this type of conversion which will eventually fail?
>
> I must have missed the doc in the Piper's manual that
> explains this (it certainly wasn't in the SPECS doc). To be
> fair, it does state:
> "Note that the REXX name for a conversion function can be
> misleading:".
> Where should I look for the doc?
>
> And... is there a better way to do this?
>
> Maybe tomorrow won't be another bad day...
>
> Mike (relapsing back to plumber's apprentice) Walter Hewitt
> Associates Any opinions expressed herein are mine alone and
> do not necessarily represent the opinions or policies of
> Hewitt Associates.
>
>
>
>
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