DOS ain't dead - indirect far jmp

indirect far jmp (Developers)

posted by Arjay, 12.05.2012, 01:07

> > iirc rayer does some rom programming stuffs, maybe it's for that?
> Yes :)
No AMIS then ;-)

> OK I'll rewrite it to call old ISR via INT.
Depending on what it is you need to do you could also use a FAR CALL to simulate the INT call, e.g.

xor bp,bp pushf call FAR [BP+0084]

where 0084 is the int offset in the IVT, Int 21h in this case. Nasty trick but sometimes useful. Not an easy example to follow but this old short code of mine uses it:

N MSG2MARK.COM E 0100 50 53 20 FF 41 43 41 44 41 4D 59 21 FF 24 FF 0D E 0110 52 4A 1A C0 18 E4 53 5A 5B 33 ED 8E D5 C1 E2 08 E 0120 0D 00 52 80 EC 49 BC FD FF 9C FF 9E 84 00 E9 CF E 0130 FE 47 52 45 45 54 49 4E 47 53 20 32 4D 41 52 4B RCX 40 W Q

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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