----- Original Message -----
From: "Tom Harper" <[email protected]>
To: <[email protected]>
Sent: Friday, April 15, 2022 3:06 AM
IMHO, the next instruction to add to z/Architecture would be an instruction to clear storage to
zeros.
Right now a number of methods are in widespread use, none of which are clean and simple. I mean,
it’s been almost sixty years.
MVCL takes three registers to set up beforehand;
So? Write yourself a macro.
XC sets the condition code and is not variable length, and the overlapping MVC
is a kluge
But it does the job well.
and not variable length either.
Use Ex.
An EX instruction is also a kluge.
All you need is the address and length to accomplish this, preferably in two
versions,
one with an immediate operand for the length
Really?! A few lines ago, you were decrying XC and MVC because they have a "fixed
length".
and another which uses, for example, a register, perhaps register zero. A long displacement would
be a plus.
To avoid issues with interruptibility, the length would need to be limited to
256 bytes.
What? Back to a limit of 256? what's the point of that?
MVCL will do as long as you want.
I don’t think the length restriction would be an issue in most cases.
There's no point in having an instruction with a length restrictionof 256.
Such an instruction might look like this:
CLEAR FieldA
Or
LLGF R0,Varlen
CLEARR
A macro reference would require one line.
Similar instructions for compare logical and move would be nice as well.
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