DOS ain't dead

User exception handler in C (Developers)

posted by Laaca , Czech republic, 18.08.2020, 20:15

> Undocumented unit cpu has some functions too, and might be more maintained.

I think that undocumented unit CPU has a potential bug.

function cr0 : longint;assembler;
      asm
         DB 0Fh,20h,0C0h
         { mov eax,cr0
           special registers are not allowed in the assembler
                parsers }
      end;


Problem is that "mov eax,cr0" is a privileged instruction. Sure, some DPMI managers let you to call it anyway but it is not sure.
And I am not sure about other OSes.

Better is to use the instruction SMSW which is non-privileged.

function cr0 : longint;assembler;
asm
mov eax,0
smsw ax 
end;


---
DOS-u-akbar!

Complete thread:

• User exception handler in C - RayeR, 24.07.2020, 13:15 (Developers)
  • User exception handler in C - Japheth, 24.07.2020, 18:07
  • User exception handler in C - Rugxulo, 24.07.2020, 18:39
  • User exception handler in C - tkchia, 24.07.2020, 20:47
    • User exception handler in C - RayeR, 30.07.2020, 13:18
      • User exception handler in C - tom, 30.07.2020, 23:54
        • User exception handler in C - RayeR, 01.08.2020, 02:13
          • User exception handler in C - Laaca, 16.08.2020, 21:27
            • User exception handler in C - Laaca, 16.08.2020, 22:38
              • User exception handler in C - Rugxulo, 17.08.2020, 22:35
                • User exception handler in C - marcov, 18.08.2020, 12:23
                  • User exception handler in C - Laaca, 18.08.2020, 20:15
                    • User exception handler in C - Rugxulo, 19.08.2020, 19:44
                      • User exception handler in C - Laaca, 19.08.2020, 21:50
                        • User exception handler in C - Rugxulo, 23.08.2020, 17:32
                          • User exception handler in C - Japheth, 23.08.2020, 20:36
            • User exception handler in C - Rugxulo, 17.08.2020, 22:26
            • User exception handler in C - tkchia, 19.08.2020, 18:52
              • User exception handler in C - marcov, 20.08.2020, 00:00
                • User exception handler in C - Laaca, 20.08.2020, 15:31
      • User exception handler in C - tkchia, 31.07.2020, 19:36
        • User exception handler in C - RayeR, 01.08.2020, 02:16
  • User exception handler in C - Guti, 27.07.2020, 08:22