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From: LDW@USCMVSA.BITNET (Leonard D Woren)
Newsgroups: comp.lang.asm370
Subject: MVCL (was Re: why code in 370 Assembler)
Message-ID: <9104260659.AA07567@ucbvax.Berkeley.EDU>
Date: 26 Apr 91 06:57:00 GMT
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Reply-To: IBM 370 Assembly Programming Discussion List
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The thread that wouldn't die...

> > ... does that MVC/MVCL
> >instruction resolve to 1 machine code instruction?

> Yes AND no: MVCL is one machine code instruction for the assembler.  ...

I've been known to remark that MVCL is an 18 byte RR instruction.
Let's see now:
    LA    Rx,source                 4
    LA    R(x+1),source_length      4
    LA    Ry,target                 4
    LA    R(y+1),target_length      4
    MVCL  Ry,Rx                     2
                                   ---
                                   18
Of course, in the most common usage it's only 16 bytes because you do
LR R(y+1),R(x+1) to set the target length.  :-)  And yes, I realize
that you often don't need all those instructions because you may have
things handy in registers.


/Leonard