How about fixing the problem you had with branch tables and introducing a new instruction JIC (branch relative indexed conditional)?
JIC *+4(15),nn J RC0ROUTINE J RC4ROUTINE J RC8ROUTINE J RCERR_RTN Where nn is an immediate value hw that limits the value of RC and Jumps to *+4+(nn+4) if it is exceeded (last valid entry + 4) On 2021-11-23 11:24 a.m., Charles Mills wrote:
Should that second instruction be an LA? I quit using branch tables. I know, they are useful, but IMHO wild branches are the worst of bugs, and so I have eschewed branch tables. The architecture could use a new instruction "branch relative indexed" or JI. So then your original code would become JI *+4(15) J RC0ROUTINE J RC4ROUTINE J RC8ROUTINE Charles
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From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Mark Hammack Sent: Tuesday, November 23, 2021 7:42 AM To:ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Base-less macros So as a related question, I started working on a 'baseless' version of a branch table macro I wrote years ago. I have it working but was curious what other people have done. In 'based' code, it typically generates something like: B *+4(15) B RC0ROUTINE B RC4ROUTINE B RC8ROUTINE etc. The best I could come up with for 'baseless' code is: LARL 14,*+((48+32+16)/8) L 14,0(15,14) BR 14 J RC0ROUTINE J RC4ROUTINE J RC8ROUTINE As to the specific question asked in the thread, I recently ran into an issue where a macro expanded by a couple of bytes which threw the literals out of the 4k 'base'. The way I took care of *most* of the issue was to go with immediate, long displacement or relative instructions as much as possible which all but eliminated the need for an LTORG or at least reduced the need for multiple LTORGs in the program.
