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
