(Assembler) PIC Interrupt Context Save and Restore

By SnipBot | Published: July 23, 2011

This code is used to save and restore the context registers of a PIC18F device before executing an interrupt service routine. FSR0 only needs to be saved

  1. ISR:
  2. ; Save processor context
  3. movwf   wSave, 0
  4. movff   STATUS, statSave
  5. movff   BSR, bsrSave
  6.  
  7. ; Save FSR0
  8. movff   FSR0L, fsr0lSave
  9. movff   FSR0H, fsr0hSave
  10.  
  11. ; Insert code here
  12.  
  13. End_Isr:
  14. ; Restore FSR0
  15. movff   fsr0lSave, FSR0L
  16. movff   fsr0hSave, FSR0H
  17.  
  18. ; Restore processor context and return
  19. movff   bsrSave, BSR
  20. movf    wSave, w, 0
  21. movff   statSave, STATUS
  22. retfie  0
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