From: nowhere@nevernet.at   
      
   On 08/01/2022 23:44, James Harris wrote:   
   > On 08/01/2022 20:10, wolfgang kern wrote:   
   >   
   > ...   
   >   
   >> Earlier versions of my OS used self-relocation, and they were small   
   >> enough to fit into the first 640K. Not more since a while ...   
   > What format did you use for relocatable files? AISI there are two choices:   
   >   
   > 1. Design your own format. Then relocation would be easy but you'd need   
   > some way to convert to that form from build tools - compiler/assembler -   
   > or to produce your own build tools.   
   >   
   > 2. Use a predefined format. Then relocation would require parsing the   
   > structure but (bugs permitting!) it would be easy to produce.   
   >   
   >   
   > FWIW, I am looking to use option 2 ATM but I have all kinds of   
   > interesting ideas for matters related to option 1. :-)   
      
   My way of self relocation was just one single variable on the very start   
   of the image in RAM (I put all other rd/wr data anyway 512 bytes upfront   
   code, similar to a PSP in DOS), so all internal and also external access   
   just added this to reference anything within code and data by SIB modes.   
      
   more previous versions used a relative CALL-Null/POP sequence to figure   
   where it was loaded, but I soon found the better solution as said above.   
   __   
   wolfgang   
      
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