"Never" is putting it a bit strong. Suppose you are -- sorry, were --
writing a macro that generates the code. Do you want a macro parameter
that specifies a one-byte work area?
BTW, the reason for omitting comments was to allow the reader a slight
frisson on figuring out how it actually works. As per the following famous
enhanced version:
*-4 EQU *
CLI *+1,B'11111100'
EX R15,*-4
BNE error
Best regards, Steve Hobson
From: "Steve Hobson" <steve_hob...@uk.ibm.com>
Sent: Wednesday, 29 August 2012 12:53 AM
>Younger readers may like to know that years ago we would test the low two
>bits of R15 for zero like this:
> CLI *+1,B'11111100'
> EX R15,*-4
> BNE error
Never necessary to do that:
STC 15,X
TM X,3
BNE ...
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