CrossWorks AVR 1.4 - mixed code C/assembler

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Franz Müller

• October 12, 2009 19:42

Hi

At the moment I try to make a project with mixed (C and assembler) code files. I found the following link in the knowledgebase for the ARM architecture:

http://rowley.zendesk.com/forums/56662/entries/46170

Is this example also usable for the AVR architecture or are there different things to keep in mind?

 

Thanks and regards

Franz

 

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• 

  Robert Wood

  • October 27, 2009 13:06

  Yes, it works similarly. Here's how I did it:

  Create a .asm file like this:

          .code
          .even
          .opt
          .export _LSBSwap
  
          .export _AllIntsOn
          .export _AllIntsOff
  
  _LSBSwap PROC

   

  ; Code goes here, any labels have a colon after them.              
        endproc

   

  Put that in your project and in your C file:

   

  extern unsigned char LSBSwap(unsigned char);

   

  And to use it in the code:

   

  FramesUnits = LSBSwap(FrameIn[0]);    // LSBSwap puts bits in correct order

   

  IIRC one byte gets passed into r23 a word into r23/r22 etc. I might be wrong about that. Might want to play with it and see how it works.

   

  Don't fotget to push and pull any registers you use! :~)

   

  Cheers,

   

  Rob

   

   

   

   

   

   

   

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  Robert Wood

  • October 27, 2009 13:08

  Sorry, ignore        

  .export _AllIntsOn
  .export _AllIntsOff

  That was for a second and third routine.

   

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