RE: [avr-gcc-list] rjmp confusion

[Dave Hansen]

From: Simon Han <address@hidden>
[...]
> 	Based on AVR instruction set documentation, rjmp is defined to be 
> "relative jump to an address within PC - 2K + 1 and PC + 2K (words)".  Then 
> it says that "for AVR microcontrollers with Program memory not exceeding 4K 
> words this instruction can address the entire memory from EVERY address 
> location".  I capitalize the word I am confused about.  How can a rjmp 
> instruction located at flash memory 3.5K jump back to flash memory location 
> at 0.5K?  This will require rjmp (-3K).

Remember that program memory is measured in bytes, but addressed (in the PC) 
as words.  Therefore, an rjmp at "memory 3.5k" (assume 3584) will be at 
address 1792, the destination "0.5k" (512) will be ad at address 256, and 
the rjump will be -1.5k.

HTH,
  -=Dave

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