ngi.s 346 B

123456789101112131415161718192021222324
  1. .define Ngi2
  2. .sect .text
  3. .sect .rom
  4. .sect .data
  5. .sect .bss
  6. .sect .text
  7. ! This subroutine negates the integer in registerpair AX.
  8. ! The negation is a one's complement plus one.
  9. Ngi2:
  10. eor #0x0FF ! one's complement A
  11. tay
  12. txa
  13. eor #0x0FF ! one's complement X
  14. tax
  15. inx ! increment X
  16. bne 1f
  17. iny ! increment A if neccesairy
  18. 1: tya
  19. rts