> -----Original Message-----
> From: IBM Mainframe Discussion List
> [mailto:[EMAIL PROTECTED] On Behalf Of Greg Price
> Sent: Wednesday, June 18, 2008 9:03 AM
> To: IBM-MAIN@BAMA.UA.EDU
> Subject: LRVH instruction - misnamed or BAD?
>
> LRVH - Load Reversed (Halfword)
>
> So it should load a reversed halfward, right?
>
> Well, sure, it swaps the byte order (compared to their order
> in storage)
> and puts them in register bits 48->63, **BUT** it leaves bits 0->47
> UNCHANGED.
>
> Now, that last part is not what LH does, is it?
>
> In my book, that's an INSERT, not a LOAD. I think it should have
> zeroed bits just like LH does. I think the LOAD (as I envisage it)
> function is more useful than the INSERT function (as it is
> implemented).
>
> Am I right or am I right? (They are the only possibilities,
> aren't they?)
>
> Cheers,
> Greg
I agree. I guess to really make this do what I would generally want, I'd
need to do something like:
LRVH R0,INTEL_HALFWORD
SLL R0,16
SRA R0,16
That would propagate the sign bit correctly. That's for only using the
32 bit register. For using 64 bit, I'd replace the 16 with 48.
--
John McKown
Senior Systems Programmer
HealthMarkets
Keeping the Promise of Affordable Coverage
Administrative Services Group
Information Technology
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