DOS ain't dead

indirect far jmp (Developers)

posted by bretjohn  , Rio Rancho, NM, 11.05.2012, 22:31

> I placed old vector at INT 85h, I'm not sure if it's safe to call int from
> another int, I don't want to mess up something. Also it increase stack
> usage, probably not problem. And I have to change ISR because it will
> return back instead of case FAR JMP... (it's INT 13h handler hook)

It's OK to call one INT from within another -- that happens all the time. You just need to be sure there aren't going to be any reentrancy issues. So, if you're vector address is stored at INT 13h in the IVT and the old INT 13h vector is stored at INT 85h, you can just issue an INT 85h. But, it will be processed as a (INT) CALL, not a JMP.

That being said, what you're doing is probably not a good idea -- using the IVT as storage space for some of your program's internal data. I'll rant one more time about AMIS here, which is what I think you should be doing instead.

Complete thread:

• indirect far jmp in NASM - RayeR, 10.05.2012, 10:46 (Developers)
  • indirect far jmp in NASM - RayeR, 10.05.2012, 13:16
    • indirect far jmp - ecm, 10.05.2012, 13:26
    • indirect far jmp in NASM - Rugxulo, 10.05.2012, 13:26
      • indirect far jmp in NASM - RayeR, 10.05.2012, 14:07
        • indirect far jmp - ecm, 10.05.2012, 15:17
          • indirect far jmp - RayeR, 11.05.2012, 00:47
            • indirect far jmp - ecm, 11.05.2012, 12:46
            • indirect far jmp - bretjohn, 11.05.2012, 18:53
              • indirect far jmp - RayeR, 11.05.2012, 19:31
                • indirect far jmp - bretjohn, 11.05.2012, 22:31
                  • indirect far jmp - ecm, 11.05.2012, 22:33
                    • indirect far jmp - RayeR, 12.05.2012, 00:33
                      • indirect far jmp - Arjay, 12.05.2012, 01:07
                        • indirect far jmp - ecm, 12.05.2012, 01:27
                          • indirect far jmp - Arjay, 12.05.2012, 11:09
                            • indirect far jmp - ecm, 12.05.2012, 21:18
                        • indirect far jmp - RayeR, 12.05.2012, 21:17
                          • indirect far jmp/call - Chaining Interrupt Service Routines - Arjay, 13.05.2012, 13:16
                      • indirect far jmp - calling old INT problem - RayeR, 13.05.2012, 04:01
                        • indirect far jmp - calling old INT problem - ecm, 13.05.2012, 04:27
                          • indirect far jmp - calling old INT problem - RayeR, 13.05.2012, 15:33
                            • indirect far jmp - calling old INT problem - bretjohn, 13.05.2012, 17:05
                              • indirect far jmp - calling old INT problem - RayeR, 13.05.2012, 17:15
                                • indirect far jmp - calling old INT problem - RayeR, 13.05.2012, 19:19
                                  • indirect far jmp - calling old INT problem - Rugxulo, 13.05.2012, 20:02
                                    • indirect far jmp - calling old INT problem - RayeR, 13.05.2012, 20:49
                                    • indirect far jmp - calling old INT problem - ecm, 13.05.2012, 23:49
                                  • indirect far jmp - calling old INT problem - ecm, 13.05.2012, 23:40
                                    • indirect far jmp - calling old INT problem - ecm, 14.05.2012, 00:07
                                      • indirect far jmp - calling old INT problem - RayeR, 14.05.2012, 01:19
                            • indirect far jmp - calling old INT problem - ecm, 13.05.2012, 23:44
                              • indirect far jmp - calling old INT problem - bretjohn, 14.05.2012, 18:30
                                • redundant override in "ss:bp" for clarity - ecm, 14.05.2012, 18:47
                                • indirect far jmp - calling old INT problem - RayeR, 14.05.2012, 18:50
                                  • indirect far jmp - calling old INT problem - bretjohn, 14.05.2012, 20:16
                                    • indirect far jmp - calling old INT problem - ecm, 14.05.2012, 20:21
                                      • indirect far jmp - calling old INT problem - bretjohn, 14.05.2012, 21:42
                                        • indirect far jmp - calling old INT problem - bretjohn, 15.05.2012, 18:45
                                          • indirect far jmp - calling old INT problem - ecm, 15.05.2012, 18:53
                                            • indirect far jmp - calling old INT problem - bretjohn, 15.05.2012, 20:13
                                              • indirect far jmp - calling old INT problem - RayeR, 17.05.2012, 01:25