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Groups > comp.sys.acorn.programmer > #2083
| From | Martin Bazley <martin.bazley@blueyonder.co.uk> |
|---|---|
| Newsgroups | comp.sys.acorn.programmer |
| Subject | Re: Assembler Help. |
| Message-ID | <bb7b24bf52.martin@blueyonder.co.uk> (permalink) |
| References | (12 earlier) <f8e3bfbb52.martin@blueyonder.co.uk> <52bbf5c233zuiderduin@hotmail.com> <mpro.m8fmp500552al01ug@wingsandbeaks.org.uk.invalid> <k07o9l$moi$2@dont-email.me> <05efb2a0-cb28-44c1-a80b-f9d9d2e339db@s2g2000vbj.googlegroups.com> |
| Organization | virginmedia.com |
| Date | 2012-08-14 14:59 +0100 |
The following bytes were arranged on 14 Aug 2012 by Gazza : > .sometxtptr : EQUD sometext > .tmpstr255ptr : EQUD tmpstr255 > > .routine : ADR Rx,sometextptr > ADR Ry,tmpstr255ptr > > ... > > So at this point Rx should point to address specified by sometext and > Ry should point to tmpstr255. They don't. They point to the addresses specified by sometextptr and tmpstr255ptr. To make them point to the data contained in those addresses (i.e. sometext and tmpstr255), you should be using LDR instead. ADR, by the way, isn't a real instruction, it's just a convenient shorthand for assembler programmers. "ADR Rx,address" assembles to the machine code for "ADD Rx,PC,(address-PC)" (or SUB, as appropriate), whatever the difference between address of the data and the address of the instruction happens to be at the point of assembly. It doesn't *load* anything, and it has the same range limitations which affect the second operand of any instruction - which is why you're using sometextptr and tmpstr255ptr in the first place, to get around these limitations. By storing your destination in memory in this way and using LDR *instead* of ADR (not using ADR all over again!), you free yourself from the ARM's limits on immediate constants. I believe we have had this particular conversation before. Many times, in fact. I have particularly vivid memories of the time you accosted me at last year's London show and demanded that we had this conversation right now. -- __<^>__ / _ _ \ You always find something in the last place you look. ( ( |_| ) ) \_> <_/ ======================= Martin Bazley ==========================
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Assembler Help. Gazza <usenet@garethlock.com> - 2012-07-10 07:09 -0700
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-07-10 08:46 -0700
Re: Assembler Help. Chris Johnson <chrisjohnson+news@spamcop.net> - 2012-07-10 18:06 +0100
Re: Assembler Help. jgharston <jgh@arcade.demon.co.uk> - 2012-07-11 11:26 -0700
Re: Assembler Help. cferris@freeRemoveuk.com.invalid - 2012-07-11 20:05 +0100
Re: Assembler Help. jgharston <jgh@arcade.demon.co.uk> - 2012-07-11 15:16 -0700
Re: Assembler Help. Steve Drain <steve@kappa.me.uk> - 2012-07-12 10:25 +0100
Re: Assembler Help. cferris@freeRemoveuk.com.invalid - 2012-07-13 09:23 +0100
Re: Assembler Help. Steve Drain <steve@kappa.me.uk> - 2012-07-13 11:16 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-07-24 05:17 -0700
Re: Assembler Help. Gavin Wraith <gavin@wra1th.plus.com> - 2012-07-24 14:02 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-07-24 06:49 -0700
Re: Assembler Help. Steve Drain <steve@kappa.me.uk> - 2012-07-24 15:03 +0100
Re: Assembler Help. usenet@garethlock.com - 2012-07-24 08:21 -0700
Re: Assembler Help. Steve Drain <steve@kappa.me.uk> - 2012-07-24 17:55 +0100
Re: Assembler Help. Theo Markettos <theom+news@chiark.greenend.org.uk> - 2012-08-03 20:26 +0100
Re: Assembler Help. cferris@freeRemoveuk.com.invalid - 2012-08-05 08:51 +0100
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-07-24 20:04 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-07-24 14:16 -0700
Re: Assembler Help. Jeremy Nicoll - news posts <jn.nntp.scrap007@wingsandbeaks.org.uk> - 2012-07-24 22:34 +0100
Re: Assembler Help. Chris Johnson <chrisjohnson+news@spamcop.net> - 2012-07-24 23:56 +0100
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-07-25 01:42 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-03 05:54 -0700
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-08-03 17:52 +0100
Re: Assembler Help. "Barry Allen (news)" <evanallen@onetel.net.uk.invalid> - 2012-08-04 10:21 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-04 15:57 -0700
Re: Assembler Help. cferris@freeRemoveuk.com.invalid - 2012-08-05 08:48 +0100
Re: Assembler Help. Martin <News03@avisoft.f9.co.uk> - 2012-08-06 10:00 +0100
Re: Assembler Help. Theo Markettos <theom+news@chiark.greenend.org.uk> - 2012-08-06 13:26 +0100
Re: Assembler Help. Martin <News03@avisoft.f9.co.uk> - 2012-08-06 23:13 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-07 08:50 -0700
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-07 15:43 -0700
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-08-08 00:52 +0100
Re: Assembler Help. usenet@garethlock.com - 2012-08-08 02:03 -0700
Re: Assembler Help. jeffrey.a.doggett@gmail.com - 2012-08-08 02:19 -0700
Re: Assembler Help. druck <news@druck.org.uk> - 2012-08-12 09:05 +0100
Re: Assembler Help. Frank de Bruijn <zuiderduin@hotmail.com> - 2012-08-08 11:40 +0200
Re: Assembler Help. Jeremy Nicoll - news posts <jn.nntp.scrap007@wingsandbeaks.org.uk> - 2012-08-08 11:34 +0100
Re: Assembler Help. Justin Fletcher <gerph@gerph.org> - 2012-08-09 21:19 +0100
Re: Assembler Help. druck <news@druck.org.uk> - 2012-08-12 09:08 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-14 05:17 -0700
Re: Assembler Help. Chris Johnson <chrisjohnson+news@spamcop.net> - 2012-08-14 14:50 +0100
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-08-14 15:03 +0100
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-08-14 14:59 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-15 17:01 -0700
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-21 03:54 -0700
Re: Assembler Help. Martin <News03@avisoft.f9.co.uk> - 2012-08-21 12:27 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-21 05:08 -0700
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-21 05:25 -0700
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-21 08:23 -0700
Re: Assembler Help. druck <news@druck.org.uk> - 2012-08-21 18:19 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-21 14:20 -0700
Re: Assembler Help. cferris@freeRemoveuk.com.invalid - 2012-08-22 09:07 +0100
Re: Assembler Help. Gazza <usenet@garethlock.com> - 2012-08-22 05:28 -0700
Re: Assembler Help. Steve Fryatt <news@stevefryatt.org.uk> - 2012-08-22 14:47 +0100
Re: Assembler Help. druck <news@druck.org.uk> - 2012-08-22 23:11 +0100
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-08-29 18:36 +0100
Re: Assembler Help. Jeremy Nicoll - news posts <jn.nntp.scrap007@wingsandbeaks.org.uk> - 2012-08-22 09:38 +0100
Re: Assembler Help. jgh@arcade.demon.co.uk (Jonathan Graham Harston) - 2012-08-08 23:15 +0100
Re: Assembler Help. Martin Bazley <martin.bazley@blueyonder.co.uk> - 2012-08-09 13:59 +0100
Re: Assembler Help. Steve Drain <steve@kappa.me.uk> - 2012-08-10 15:50 +0100
Re: Assembler Help. Frank de Bruijn <zuiderduin@hotmail.com> - 2012-07-11 08:30 +0200
Re: Assembler Help. cferris@freeRemoveuk.com.invalid - 2012-07-11 09:26 +0100
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