Newsgroups: comp.lang.asm370
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!news.cs.indiana.edu!ux1.cso.uiuc.edu!phil
From: phil@ux1.cso.uiuc.edu (Phil Howard KA9WGN)
Subject: Re: MVCL (was Re: why code in 370 Assembler)
Message-ID: <1991Apr29.041026.15906@ux1.cso.uiuc.edu>
Organization: University of Illinois at Urbana
References: <9104260659.AA07567@ucbvax.Berkeley.EDU> <9104261340.AA14703@ucbvax.Berkeley.EDU>
Distribution: inet
Date: Mon, 29 Apr 1991 04:10:26 GMT
Lines: 19

rickert@CS.NIU.EDU (Neil Rickert) writes:

> But of course your 18 bytes is a serious underestimate.  After all you must
>first save the current contents of the registers, and later restore them.
>If something is really worth doing in assembler, you are probably going to
>have all registers tied up, so there just aren't two even/odd pairs readily
>available.  MVCL is mostly useful when you need its feature of padding the
>destination.

In most cases, when I need an MVCL, the addresses I need are already in
the registers.  Careful register reallocation gets them into the correct
registers.  For instance I try to keep address/length data in even/odd
pairs even before I anticipate needing an MVCL.  Only rarely do I need
to dump something out of registers to do an MVCL.
-- 
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