Hi.   I tried to access 32-bit addresses (such as 000A:0000) through _x386_map_physical_memory but the program usually crashes with the warning: "General Protection Fault" and it gives me all the register values. Is there a way I can access the address without using any fancy functions that is provided, or by using the function provided effeciently?

I actually tried to access address not associated with any hardware (for example.  0005:1836) and it didn't work. The 000A000 works fine but this address didn't work. The reason I am tring to access this location is because the real-mode video-interrupt 0x10 only outputs buffer in the conventional memory. Is it possible that since this is a 32-bit protected mode environment, pointers to conventional addresses are illegal?   If so, can you give me some ideas on how I can access conventional memory? Thanks.

To access the display directly, try the disp functions in disp.h. That will likely work better (and it's portable to win32 too!).

    Imran Haider wrote in message <9qvefh$124m$1@digitaldaemon.com>...
    Hi.   I tried to access 32-bit addresses (such as 000A:0000) through _x386_map_physical_memory but the program usually crashes with the warning: "General Protection Fault" and it gives me all the register values. Is there a way I can access the address without using any fancy functions that is provided, or by using the function provided effeciently?

    I actually tried to access address not associated with any hardware (for example.  0005:1836) and it didn't work. The 000A000 works fine but this address didn't work. The reason I am tring to access this location is because the real-mode video-interrupt 0x10 only outputs buffer in the conventional memory. Is it possible that since this is a 32-bit protected mode environment, pointers to conventional addresses are illegal?   If so, can you give me some ideas on how I can access conventional memory? Thanks.

Imran Haider schrieb...
> 
> Hi.   I tried to access 32-bit addresses (such as 000A:0000) through _x386_map_physical_memory but the program usually crashes with the warning: "General Protection Fault" and it gives me all the register values. Is there a way I can access the address without using any fancy functions that is provided, or by using the function provided effeciently?

Try to use _x386_zero_base_ptr, that is declared in dos.h as

   void *_x386_zero_base_ptr;

You now can build a 32 bit absolute address by adding a 32bit offset to this pointer:

  char *ScreenAtA000 = (char*)_x386_zero_base_ptr + 0xA0000;

Note that you don't use segment:offset in this case but a linear memory address.


Regards,
	Heinz

see a reply I sent in this group: "Re: Accessing VRAM directly" there is evrything to manipulate pointers in it

Ciao

Roland


Imran Haider a écrit :

> Hi.   I tried to access 32-bit addresses (such as 000A:0000) through _x386_map_physical_memory but the program usually crashes with the warning: "General Protection Fault" and it gives me all the register values. Is there a way I can access the address without using any fancy functions that is provided, or by using the function provided effeciently? I actually tried to access address not associated with any hardware (for example.  0005:1836) and it didn't work. The 000A000 works fine but this address didn't work. The reason I am tring to access this location is because the real-mode video-interrupt 0x10 only outputs buffer in the conventional memory. Is it possible that since this is a 32-bit protected mode environment, pointers to conventional addresses are illegal?   If so, can you give me some ideas on how I can access conventional memory? Thanks.

I added yours and Heinz's comments to the FAQ. Thanks!

    www.digitalmars.com/faq.html


Roland wrote in message <3BD56D53.E8D63C85@ronetech.com>...
>see a reply I sent in this group: "Re: Accessing VRAM directly" there is evrything to manipulate pointers in it
>
>Ciao
>
>Roland
>
>
>Imran Haider a écrit :
>
>> Hi.   I tried to access 32-bit addresses (such as 000A:0000) through _x386_map_physical_memory but the program usually crashes with the warning: "General Protection Fault" and it gives me all the register values. Is there a way I can access the address without using any fancy functions that is provided, or by using the function provided effeciently? I actually tried to access address not associated with any hardware (for example.  0005:1836) and it didn't work. The 000A000 works fine but this address didn't work. The reason I am tring to access this location is because the real-mode video-interrupt 0x10 only outputs buffer in the conventional memory. Is it possible that since this is a 32-bit protected mode environment, pointers to conventional addresses are illegal?   If so, can you give me some ideas on how I can access conventional memory? Thanks.
>