Using C++ in real mode(Turbo C++)

[gaiety]

I have see the osfaq about using C++ for os design. It need to modify a little bit for using C++. However, the version for faq is for djgpp and it is 32Bit.

Now, I am developing a os that is real mode. The background is:

Compiler: Nasm, Turbo C++ 3.0
CPU: Pentium 433Mhz
Developing platform: Window XP
OS design: Real mode, maybe like the first version of old Dos.

So, how to make my os design using Object Oriented Design. I am using Turbo C++, not djgpp. Have anybody done that before.

Thank you for answering my question.

[Euwinei]

if turbo c++ is so uncommon, use djgpp, or just use 'c'.

[Pype.Clicker]

actually, the scope of the whole FAQ is ia32 protected mode OS development. Though borland's Turbo C++ is quite a different beast, the idea is roughly the same:
- find a loader that supports your compiler's output. EXE bootloaders were quite common a few years ago and i'd say XOSL should still support it.
- isolate the requirement to support language runtime (like malloc) and provide substitutes for them.
- Check if you can disable what you don't need (exceptions, rtti and other complex stuff)

[B.E]

Asuming that you have the IDE with it, look at the command line help

[gaiety]

http://www.invalidsoftware.net/os/?the_id=11

The URL above is about writing a kernel in C++, it is for 32bit Djgpp. It is the nearest resource I get. I try to use it's concept in my real mode kernel. But I need some hand.

objdump -h Kernel.o > Kernel.dis
Redirects the output of objdump to a file named Kernel.dis

Step 4 - Open the Kernel.dis with a text editor (Notepad, WordPad, my preferred choice is TextPad)

Look for something like this in the file
7 .ctors 00000004 000000f4 000000f4 00000294 2**2
CONTENTS, ALLOC, LOAD, RELOC, DATA
8 .dtors 00000004 000000f8 000000f8 00000298 2**2
CONTENTS, ALLOC, LOAD, RELOC, DATA.
If they are present, you can use solution 1.

This is what I get from the tutorial. So, for the first step, I need to check if the .ctors and .dtors(It may be other name in my object file that create from Turbo C++) is in the obj file. However, the object file I create from the Turbo C++ is OMF format, Djgpp can't read OMF format.

The first problem, Turbo C++ don't have objdump, the nearest tool I get is objxref, and it is the dump file I get.

Code: Select all

WARNING: Unresolved symbol operator new(unsigned int) in module TTTT
WARNING: Unresolved symbol operator delete(void near*) in module TTTT
WARNING: Unresolved symbol _printf in module TTTT


PUBLIC SYMBOL DEFINITIONS BY SYMBOL NAME

SYMBOL                                  DEFINED IN

operator delete(void near*)             -undefined-
operator new(unsigned int)              -undefined-
_kk                                     TTTT
_main                                   TTTT
_printf                                 -undefined-


PUBLIC SYMBOL DEFINITIONS BY MODULE NAME

MODULE: -undefined- defines the following symbols
        operator delete(void near*)
        operator new(unsigned int)
        _printf
MODULE: TTTT defines the following symbols
        _kk
        _main


EXTERNAL SYMBOL REFERENCES BY MODULE NAME

MODULE: -undefined- references the following symbols
MODULE: TTTT references the following symbols
        operator delete(void near*)
        operator new(unsigned int)
        _printf


PUBLIC SYMBOL DEFINITION AND REFERENCES BY SYMBOL NAME

operator delete(void near*) (-undefined-)
        TTTT
operator new(unsigned int) (-undefined-)
        TTTT
_printf (-undefined-)
        TTTT


MODULE SIZES BY SEGMENT

_BSS, PUBLIC
             0 (00000h)    total

_DATA, PUBLIC
            22 (00016h)    TTTT
            22 (00016h)    total

_EXIT_, PUBLIC
             6 (00006h)    TTTT
             6 (00006h)    total

_INIT_, PUBLIC
             6 (00006h)    TTTT
             6 (00006h)    total

_TEXT, PUBLIC
            48 (00030h)    TTTT
            48 (00030h)    total



MODULE SIZES BY CLASS

BSS
             0 (00000h)    total

CODE
            48 (00030h)    _TEXT, TTTT
            48 (00030h)    total

DATA
            22 (00016h)    _DATA, TTTT
            22 (00016h)    total

EXITDATA
             6 (00006h)    _EXIT_, TTTT
             6 (00006h)    total

INITDATA
             6 (00006h)    _INIT_, TTTT
             6 (00006h)    total



UNREFERENCED PUBLIC SYMBOLS BY MODULE NAME

MODULE: TTTT defines the following unreferenced symbols
        _kk
        _main

Symbols  = 5
Modules  = 2
Segments = 5
Classes  = 5

_kk is the test class I create, do you have any idea how to use of the data above.

Or any other tool that can dump the object file with OMF format.

#2 I have some question, first, what is BSS. And another thing, when the linker link the object file, will it collect all the global data and put all of then in some place. Or we need to setup where to put the global data in some place.

Thank you for answering my question. I know it is hard to solve it, but any help will be nice.

[Pype.Clicker]

i suggest you get a copy of "linkers and loaders" (free pdfs around) and digest that first. I also suggest you really check your motivation for 16 bits (you do whatever you want, but considering the difficulty to get good tools, etc. does it really worth the pain ? what do you want to do that couldn't be done easily in 32 bits ?)

you may also wish to get a copy of OMF file format (e.g. at "wotsit.org")