Missed that. Too early (local time) to be reading tech documents. "Waiter! More caffeine!!" Hum, I wonder if that makes me a drug addict?
Don't know if there is really much of any difference between RLLG and SLLG in my case since I don't care one way or the other about the low word of R0. So whether it is F'0' or F'junk' doesn't matter to me in this code. Well, thinking about it, it is "nicer" to know that r0.32-63 is zero. Might be important "some day", some where, but not today or here. I don't know what I picked up on RLLG rather than SLLG. Likely because, as you just noticed, I assumed that SLLG was the Grande version of SLL (shift a register and put result in same register). I actually had to look at the RLLG instruction. My initial code was "LR R0,R13 / RLLG R0,32" which make the same assumption. When that didn't assemble, _then_ I read the documentation on RLLG. Yes, bad me. On Thu, Jun 27, 2013 at 7:39 AM, David Stokes <[email protected]> wrote: > Well actually you write SLLG R0,R13,32 - it has three operands and works > much like RLLG, R13 here remaining unchanged. > > -----Ursprüngliche Nachricht----- > Von: IBM Mainframe Assembler List [mailto:[email protected]] > Im Auftrag von John McKown > Gesendet: Donnerstag, 27. Juni 2013 14:10 > An: [email protected] > Betreff: Re: how to: document usage of bit(s) of a register. > > Hum. That is a possibility. But why replace 1 instruction with 2? > > RLLG R0,R13,32 > > vs. > > LR R0,R13 > SLLG R0,32 > > RLLG is 6 bytes. LR+SLLG is 2+6==8 bytes. So both sequences end up doing > what I want. And, to me, a single 6 byte instruction is "better" than 2 > instructions totaling 8 bytes. Admitted, the difference is moot in most > cases. But why not be as efficient as possible, when it is not any harder > to code? > > On Wed, Jun 26, 2013 at 10:32 PM, Robert A. Rosenberg <[email protected] > >wrote: > > > At 21:06 -0500 on 06/26/2013, John McKown wrote about Re: how to: > > document usage of bit(s) of a register.: > > > > > > But, in this code, I did not care what happened to bits 0-31 of R13 > > or > >> anything in R0. I could not do the simple LR R0,R13 because I use the > >> lower fullword of R0 later in the code. > >> > > > > So why not LR R0,R13 followed by a SHIFT LEFT GRANDE 32 Bits of R0 > > (assuming that there is such a command)? > > > > > > -- > This is a test of the Emergency Broadcast System. If this had been an > actual emergency, do you really think we'd stick around to tell you? > > Maranatha! <>< > John McKown > -- This is a test of the Emergency Broadcast System. If this had been an actual emergency, do you really think we'd stick around to tell you? Maranatha! <>< John McKown
