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Re: "Using" statement?

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John W Kennedy <jwkenne@attglobal.net> wrote:

Didn't see Pete's post since I killfile everything from google

> On 2012-07-12 15:36:32 +0000, Pete Nelson said:
> 
> > On Friday, July 6, 2012 10:24:16 AM UTC-5, John W Kennedy wrote:
> >> But, as I say, if you are writing code expressly for z/Architecture,> 
> >> and use only the Branch Relative family of instructions, and put all> 
> >> your data in a separate CSECT or DSECT (or PSECT), you do not need a> 
> >> base register for your code CSECT. That&#39;s why the Branch Relative> 
> >> instructions were invented -- so that you have one more general> 
> >> register to use for other purposes.
> >> 
> > Basically true, although whether your literal pool and constants are in 
> > a separate CSECT or the same CSECT as your executable code, a base 
> > register is still needed to address the data.  For small programs, you 
> > probably end up using just as many base registers either way; when the 
> > size of your executable code approaches/exceeds 4K, then you start 
> > avoiding register starvation by using relative branching.

It's true many people allocate additional base registers when code exceeds
4K but there is another way around this and I have written and worked on
substantial pieces of code that use one code base register no matter how
large the CSECT. There is really no excuse to use more than one code base
register, and I am saying that in reference to OS/360, not just since the
branch relative and immediate facility came out.

> 
> Not if you have the wit to put LTORG in your static-readonly-data CSECT.

It's a good idea to use LTORG to organize code and read-only data to
preserve locality of reference. In fact if you don't use it correctly you
often run into base addressing problems as parm lists for macros go out of
range. 

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"Using" statement? hancock4@bbs.cpcn.com - 2012-07-06 06:52 -0700
  Re: "Using" statement? John W Kennedy <jwkenne@attglobal.net> - 2012-07-06 11:24 -0400
    Re: "Using" statement? hancock4@bbs.cpcn.com - 2012-07-06 10:15 -0700
    Re: "Using" statement? Fritz Wuehler <fritz@spamexpire-201207.rodent.frell.theremailer.net> - 2012-07-12 07:31 +0200
      Re: "Using" statement? John W Kennedy <jwkenne@attglobal.net> - 2012-07-12 22:09 -0400
    Re: "Using" statement? Pete Nelson <plnelsonoma@yahoo.com> - 2012-07-12 08:36 -0700
      Re: "Using" statement? John W Kennedy <jwkenne@attglobal.net> - 2012-07-12 22:13 -0400
        Re: "Using" statement? Fritz Wuehler <fritz@spamexpire-201207.rodent.frell.theremailer.net> - 2012-07-13 14:12 +0200
          Re: "Using" statement? John W Kennedy <jwkenne@attglobal.net> - 2012-07-13 13:57 -0400
            Re: "Using" statement? Anonymous <noreply@breaka.net> - 2012-07-15 05:54 -0400
              Re: "Using" statement? -  JEmebius <jemebius@xs4all.nl> - 2012-07-30 22:09 +0100
                Re: "Using" statement? -- JEmebius <jemebius@xs4all.nl> - 2012-07-30 22:13 +0100
                Re: "Using" statement? --- JEmebius <jemebius@xs4all.nl> - 2012-07-30 22:19 +0100
                Re: "Using" statement? --- woodag@trap.ozemail.com.au (Andy Wood) - 2012-07-31 06:22 +0000
                Re: "Using" statement? --- reply JEmebius <jemebius@xs4all.nl> - 2012-08-01 02:44 +0100
                Re: "Using" statement? - Fritz Wuehler <fritz@spamexpire-201207.rodent.frell.theremailer.net> - 2012-07-31 20:46 +0200
                Re: "Using" statement? - reply JEmebius <jemebius@xs4all.nl> - 2012-08-01 03:10 +0100
                Re: "Using" statement? - reply Fritz Wuehler <fritz@spamexpire-201208.rodent.frell.theremailer.net> - 2012-08-07 16:36 +0200
                Re: "Using" statement? - reply Nomen Nescio <nobody@dizum.com> - 2012-08-07 21:33 +0200
                Re: "Using" statement? - reply Clark F Morris <cfmpublic@ns.sympatico.ca> - 2012-08-07 18:13 -0300
                Re: "Using" statement? - "Michel Castelein" <arcis@advalvas.be.without.this.no.spam.tail> - 2012-08-03 11:13 +0200
                Re: "Using" statement? - Anonymous <nobody@remailer.paranoici.org> - 2012-08-03 13:05 +0000
                Re: "Using" statement? - Allodoxaphobia <knock_yourself_out@example.net> - 2012-08-03 13:29 +0000
                Re: "Using" statement? - WAB JEmebius <jemebius@xs4all.nl> - 2012-08-04 00:03 +0100
                Re: "Using" statement? - WAB Allodoxaphobia <knock_yourself_out@example.net> - 2012-08-04 03:14 +0000
                Re: "Using" statement? - Nomen Nescio <nobody@dizum.com> - 2012-08-06 15:15 +0200
  Re: "Using" statement? alistair.j.l.maclean@gmail.com - 2012-08-19 05:58 -0700
    Re: "Using" statement? John W Kennedy <jwkenne@attglobal.net> - 2012-08-19 13:15 -0400
      Re: "Using" statement? Nomen Nescio <nobody@dizum.com> - 2012-08-19 22:20 +0200
        Re: "Using" statement? John W Kennedy <jwkenne@attglobal.net> - 2012-08-19 18:30 -0400

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