DOS ain't dead

Memory mapped devices from resl mode (Developers)

posted by Laaca , Czech republic, 27.02.2020, 17:50

> In DJGPP I use DPMI function for physical memory mapping. If you have some
> DPMI wrappers in FPC you can use it too.

In FPC I also can use the physical memory mapping. I use it for example for the LFB access or for ACPI.
However it is mapped into different segment than the default DS.

For accesing such mapped areas I have to use my own assembler wrappers. Like:
FarPokeB(segm:word;offs:dword;value:byte);assember;
asm
push es
mov ax,segm
mov es,ax
mov edi,offs
mov es:[edi],value
pop es
end;

Is possible to map it somehow into "main" address space to be able to use normal pascal code like this?

var dev_base:Pchar;
begin
dev_base:=Get_dev_base;
dev_base[offset]:=value;
...

I know that it is possible to extend the DS segment limit to reach the 4GB but I am not sure about compatibility with Win98, win XP, etc...

---
DOS-u-akbar!

Complete thread:

• Memory mapped devices from resl mode - Laaca, 26.02.2020, 12:11 (Developers)
  • Memory mapped devices from resl mode - Khusraw, 26.02.2020, 12:35
  • Memory mapped devices from resl mode - RayeR, 27.02.2020, 05:27
    • Memory mapped devices from resl mode - Khusraw, 27.02.2020, 09:07
      • Memory mapped devices from resl mode - Laaca, 04.03.2020, 14:01
        • Memory mapped devices from resl mode - Khusraw, 04.03.2020, 15:02
          • Memory mapped devices from resl mode - Laaca, 04.03.2020, 15:08
            • Memory mapped devices from resl mode - Khusraw, 04.03.2020, 15:23
            • Memory mapped devices from resl mode - Khusraw, 04.03.2020, 15:36
            • Memory mapped devices from resl mode - Khusraw, 04.03.2020, 16:55
              • Memory mapped devices from resl mode - Laaca, 04.03.2020, 18:54
                • Memory mapped devices from resl mode - Khusraw, 04.03.2020, 19:33
    • Memory mapped devices from resl mode - Laaca, 27.02.2020, 17:50
      • Memory mapped devices from resl mode - Khusraw, 27.02.2020, 20:25
        • Memory mapped devices from resl mode - KormaX, 01.03.2020, 22:23
          • Memory mapped devices from resl mode - Zyzzle, 02.03.2020, 06:10
            • Memory mapped devices from resl mode - KormaX, 12.05.2020, 11:21
        • Memory mapped devices from resl mode - marcov, 02.03.2020, 15:43
          • Memory mapped devices from resl mode - Khusraw, 02.03.2020, 19:39
            • Memory mapped devices from resl mode - marcov, 02.03.2020, 23:13
              • Memory mapped devices from real mode - Rugxulo, 03.03.2020, 06:11
                • Memory mapped devices from real mode - marcov, 03.03.2020, 10:12
                  • Memory mapped devices from real mode - Rugxulo, 03.03.2020, 22:12
              • Memory mapped devices from resl mode - Khusraw, 03.03.2020, 13:34