On 8/6/2018 8:23 AM, Keven wrote:
Ditto for
EX R0,*
except that you get a 0C3 program interrupt instead, which is usually a sign of
code scuttling itself and can be treated as such in recovery routines.
Yes, I used the 'EX R0,*' technique back in the 80s and early 90s before
R&I existed. However, it requires more code to implement and does not
work with "baseless" code. For example, let's suppose we have a "should
never occur" condition where R1>R14.
In 2018, I will code:
CGR R1,R14
JH *+2
Using the old-school 'EX R0,*' technique, I would need to code:
IF CGR,R1,GT,R14
EX R0,*
ENDIF ,
which generates a conditional branch *around* the 'EX R0,*' instruction.
Both are effective, but for performance reasons I prefer a branch that
is never taken to one that is always taken. Also, these days I don't
have a base register covering my code, so I would need to use EXRL
instead which only works on z10 and higher machines.
--
Phoenix Software International
Edward E. Jaffe
831 Parkview Drive North
El Segundo, CA 90245
https://www.phoenixsoftware.com/
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