On Friday, 08/01/2008 at 11:43 EDT, "Schuh, Richard" <[EMAIL PROTECTED]> wrote: > I would have thought that "LA R15,32" would have been a better > instruction to use than "L R15, =A(32)". I know that in olden days it > burned less carbon. I don't know what the comparison with the LHI would > be, but imagine that the two would be pretty close since both actually > load the operands when the instruction is fetched, with no memory access > needed.
Using LOAD ADDRESS requires that you learn all the little rules - The operand has to be 0-4095 (it's a displacement) - The maximum value of the register isn't what you think it is - That maximum value is different in AMODE 24 than it is in AMODE 31 - There's no overflow protection with LA R1,10(,R1) since it isn't an arithmetic operation - Don't forget the comma in (,R1) If you could live with it, no problem, but it wasn't for the uninitiated. That's the nice thing about LHI, it was designed to load a number into a register, not an address. Now if you want to increment a register by 10: AHI R1,10 Just hoping folks learned something new today. I'll be the first to admit that these new (NOT!) instructions don't come naturally to my fingertips. Alan Altmark z/VM Development IBM Endicott
