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Subject: 
Re: How to make your own assembly code position independant
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Tue, 8 Jun 1999 23:23:45 GMT
Original-From: 
Charles Hacker EAS <C.Hacker@ste./stopspammers/gu.edu.au>
Reply-To: 
C.Hacker@mailbox+stopspam+.gu.edu.au
Viewed: 
986 times
  
Marobi,

Do not know much about IC and assembly code downloading.
However, I have produced a system for programming the HandyBoard with
Assembly/machine code.  This system may help you.

It can be downloaded from:

http://132.234.46.5/Programs/HBoard/Index.shtml


Hi,

I am currently trying to get some existing assembly code (not written by me) loaded into the HB.
It loads fine, but everything gets messed up after running it.
The exact addresss of this code is not known at the time of assembly and IC just loads it in memory
after the stuff that it already loaded.
This means code needs to be position independant ( or does IC have a kind of loader ??)
What are the 'mistakes' to make code dependant on its position in memory and how to solve ?

Can anybody shine some light on it ?
I even do not exactly understand the example in the HB manual on installing an interrupt routine of your own.
This code uses the construct of 'LDD #interrupt_code_start, STD TOC4INT,X'. I know it works but ....
#interrupt_code_start is just an address generated during assembly, which is a 'fictive address'.
The begin address of this interrupt-routine as stated during assembly is not the same as the load address when loaded.
How does this stuff work ?

I am stuck. It works but I do not exactly understand how.

Please help ......


Rien
rien@direct.A2000.nl


Charles Hacker
Lecturer in Electronics, Computing and Physics
School of Engineering
Griffith University - Gold Coast
PMB 50 Gold Coast Mail Centre
Southport Queensland 9726
Australia.
Email - C.Hacker@mailbox.gu.edu.au
Ph. (07) 5594 8670
Fax.(07) 5594 8065



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