Nonsense; a good comment makes it perfectly clear and not at all elitist or opaque. Doing it without a comment, OTOH, is bad form.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Assembler List <ASSEMBLER-LIST@listserv.uga.edu> on behalf of Paul Gilmartin <00000014e0e4a59b-dmarc-requ...@listserv.uga.edu> Sent: Monday, August 6, 2018 10:51 AM To: ASSEMBLER-LIST@listserv.uga.edu Subject: Re: EX On 2018-08-06, at 08:35:57, Ed Jaffe wrote: > We use 'Jxx *+2' which disturbs no registers and is guaranteed to fail with > an 0C1. > I am *not* going to read the PoOps to learn why that "is guaranteed to fail". I'm merely dismissing it as elitist opaque code. Comments help only slightly. > On 8/6/2018 3:10 AM, Jonathan Scott wrote: >> J *+1 isn't even possible, as the hardware offset for relative >> addressing is in halfwords. >> >> For many years I have been using a conditional TRAP macro which >> is equivalent to >> BC cond,*+1 >> but which is coded using LA with an ORG back to change the >> opcode, to avoid getting an error message. This avoids a branch >> in the normal case. It is primarily used for integrity and >> consistency checks, and my recovery routine recognizes this >> convention and reports it as "TRAP occurred at offset &1 in &2". >> John Gilmore has argued, reasonably, in IBM-MAIN, for proper use of the ABEND macro rather than such flamboyant stunts. -- gil
