Checksum on code ??

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1 total messages Started by Emile Tue, 04 Aug 1992 15:32

#89

Author: Emile
Date: Tue, 04 Aug 1992 15:32

48 lines
1817 bytes

Hello!

At the moment I am designing a "checksum"-module to check if the object code
of my program has for some mysterious reason changed (Believe me, some bits
are toggled by Magic). To do this, I read the .map file and scan for the
SC code line:
             
Example:

  Processor Load Map
  Processor  1    T800
      Memory layout                         first byte        last byte
  Work space                                #8000008C         #8000036B
  Configuration code                        #8000036C         #8000037F
  SC code from file check.c8h               #80000380         #80009E9B
  No libraries loaded
  Separate vector workspace                 #80009E9C         #8001EE3B

  <stuff deleted>

From this file I would read the starting address #80000380 and the last
address #800009E9B

However, the code turns out to be changed during program execution! 
Appearantly, some variables (??) are stored in the code segment, making it
impossible to calculate a checksum.

My questions are:

1. Does anyone know what kind of data is stored in the code segment?

2. Is it possible to determine a stable part of the code? Preferrably a very
   large part...

3. Has anyone tried something like a checksum on the code before?

4. Any more suggestions??


Thanks in advance.

Sincerely,


Emile van Gerwen
PTT Research Neher Laboratories

M.J.A.M.vanGerwen@research.ptt.nl

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