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From: amdahl!terry@APPLE.COM ("Lewis T. Flynn")
Newsgroups: comp.lang.asm370
Subject: Re:  Need string handling macros
Message-ID: <9011092109.AA05152@ucbvax.Berkeley.EDU>
Date: 9 Nov 90 19:39:21 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: IBM 370 Assembly Programming Discussion List
              <ASM370@OHSTVMA.BITNET>
Distribution: inet
Organization: The Internet
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In article <9011081730.AA21056@ucbvax.Berkeley.EDU> IBM 370 Assembly
        Programming Discussion List <ASM370@OHSTVMA.BITNET> writes:
>> If you're coding in 370 Assembler, then simply use the equivalent
>> machine instructions.  SUBSTR ends up being either an EX (Execute) of
>> an MVC (Move) instruction for "short" strings ...
>
>Better, use MVCK.  The length is expected to be in a register so you

Uhhh, I don't think so. On most machines, this instruction should be
slower than MVCL and has the side effect of needing to know the correct
key (using the wrong one will generate a privileged operation exception
in problem state). Plus this will only work for for lengths of 256 or
less. The suggested EX of an MVC will be substantially faster on nearly
all machines for this case and a pure MVC will be faster yet.

Terry