John,
My comments were based on what the previous people had been discussing, namely
a branch table. An address table is a very viable alternative.
Item of note, unless you are working with all your own code, you have to
validate the value in R15 before just using it to branch into a branch table
with tests that the value is within limits and the lower 2 bits are not on.
Such as:
BALR r14,r15 Call your routine
LR R14,R15 DON'T DISTROY R15
CHI R15,16 CHECK HIGH LIMIT
JH BADRETURN TOO BIG? DIE WITH MESSAGE
N R14,=XL4'00000003' ANY STRAY BITS?
JNZ BADRETURN YES, DIE WITH MESSAGE
B *+4(R15) BRANCH ACCORDING TO RC
...
What I normally do is check for zero, if that is what you expect most often,
then, if that fails, go through all the gyrations.
BALR r14,r15 Call your routine
LTR R14,R15 DID WE GET ZERO AS EXPECTED?
BZ RCZERO YES, ->
CHI R15,16 CHECK HIGH LIMIT
JH BADRETURN TOO BIG? DIE WITH MESSAGE
N R14,=XL4'00000003' ANY STRAY BITS?
JNZ BADRETURN YES, DIE WITH MESSAGE
B *+4(R15) BRANCH ACCORDING TO RC
...
I'm sure we all have our own techniques.
Chris Blaicher
Principal Software Engineer, Software Development
Syncsort Incorporated
50 Tice Boulevard, Woodcliff Lake, NJ 07677
P: 201-930-8260 | M: 512-627-3803
E: [email protected]
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of John Gilmore
Sent: Wednesday, May 08, 2013 3:51 PM
To: [email protected]
Subject: Re: Return codes
Chris Blaicher,
Your sort of B/T has important uses, but one composed only of addresses is
useful too. Perhaps it shoul;d be called an address table to avoid confusion.
I will; send you an example privately.
John Gilmore, Ashland, MA 01721 - USA
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