Steve, Some of my macros generate a CALL or LINK to a subroutine and pass a parameter list consisting, in part, of the address of storage locations specified through arguments on the macro. In generating the storage address (reentrant code), a LA or LAE(based), or LARL (baseless) would be used.
You're right about calling CSECT or DESCT based. I was referring to the code I needed to generate rather than the location of the symbol. I guess what irks me is that the macro has no way of knowing what to generate. There is a hole in the assemble architecture. For example, before baseless, when I reference a symbol, the assembler knows how to resolve the storage location. It would lookup the symbol, determine the base register for the storage and the displacement, and generate the machine code. John -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of Steve Comstock Sent: Monday, December 20, 2010 9:53 AM To: [email protected] Subject: Re: Baseless vs Based On 12/20/2010 7:30 AM, Bodoh John Robert wrote: > Martin, > > As I understand LARL, the current PSW is used as the > base to address the symbol. If the symbol is in a > DSECT, the LARL instruction should generate an assembler > error. > > John [I am not Martin, but it is my comment you are responding to] Ah! I see. Then perhaps what you are _really_ after has nothing really to do with baseless vs. based. What you are really after is knowing if a data item is located in a DSECT or in the CSECT being run. Is that right? If an item is in a DSECT, it is, of necessity, based off some register. Then, for example, you would need, say, LA instead of LARL. But you must realize that so-called baseless programming usually needs a base register for data items. I come back to my previous question: what instructions are you thinking of where you would need to choose between based and baseless? From the perspective of most software developers, it is more critical to be sensitive to the underlying hardware: which instructions are available on the machine I am running? For those cases you either run code with lots of checking for the host machine or you only use instructions supported by all models for your customer base. > > -----Original Message----- > From: IBM Mainframe Assembler List [mailto:[email protected]] > On Behalf Of Steve Comstock > Sent: Monday, December 20, 2010 9:25 AM > To: [email protected] > Subject: Re: Baseless vs Based > > On 12/20/2010 7:05 AM, Bodoh John Robert wrote: >> Ed, Martin, John, Tony, et al, >> >> What I am doing is creating macros that are used by any other >> application. I was hoping to avoid having the user of these >> macros have to specify the technique needed to address symbols. > >> That sounds clutzy and it nowhere else in the assembler do I >> have to tell the assembler that kind of detail. >> >> At the time the macro is being used, the macro does not know >> whether baseless coding is being used or not and whether or not >> a symbol is within the current CSECT or not. If the symbol is >> within the current CSECT and code invoking the macro is using >> baseless coding, the macro MUST use baseless instructions. > > >> AsI understand it, the symbol is within the current CSECT, >> baseless instructions can be used whether or not the invoking >> code is using baseless or not. Otherwise, based instructions >> MUST be used. > > I'm at a loss here. First, you reference symbols for one > of two reasons: 1) a target for a branch or execute instruction, > and 2) a location for an operand. > > In case 1), you can always use the so-called baseless instructions; > in case 2), it depends on the operation you need to perform. > > For example, loading an address of a location can always be done > by LARL - unless the item is at an odd address! If you need to > work with packed decimal data, you must use the xP instructions, > all of which require base / displacement. > > What instructions are you thinking of where you would choose > between baseless and based? > >> >> I am surprised this not considered a hole in the assembler >> and is not more pervasive than just for me and my simple case. >> Do not other macros have the same problem? >> >> John >> >> -----Original Message----- >> From: IBM Mainframe Assembler List [mailto:[email protected]] >> On Behalf Of Martin Trübner >> Sent: Saturday, December 18, 2010 3:55 AM >> To: [email protected] >> Subject: Re: Baseless vs Based >> >> Ed, >> >> While I understand your point (missed you anyway in this thread ;-) ) I >> do not see the word DSECT mentioned in the OP-s stmt. >> >> John, was your question as simple as I assume or was it as >> sophisticated as Tony and Ed answered (with solutions from John E. and >> Paul)? >> >> -- >> Martin >> >> Pi_cap_CPU - all you ever need around MWLC/SCRT/CMT in z/VSE >> more at http://www.picapcpu.de >> > > > -- > > Kind regards, > > -Steve Comstock > The Trainer's Friend, Inc. > > 303-393-8716 > http://www.trainersfriend.com > > * To get a good Return on your Investment, first make an investment! > + Training your people is an excellent investment > > * Try our new tool for calculating your Return On Investment > for training dollars at > http://www.trainersfriend.com/ROI/roi.html > -- Kind regards, -Steve Comstock The Trainer's Friend, Inc. 303-393-8716 http://www.trainersfriend.com * To get a good Return on your Investment, first make an investment! + Training your people is an excellent investment * Try our new tool for calculating your Return On Investment for training dollars at http://www.trainersfriend.com/ROI/roi.html
