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https://github.com/dosemu2/fdpp

FreeDOS plus-plus, 64bit DOS
https://github.com/dosemu2/fdpp

c c-plus-plus cplusplus-11 cpp11 dos freedos msdos

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FreeDOS plus-plus, 64bit DOS

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README 

        
# fdpp



## what is fdpp?

fdpp is a 64-bit DOS core.


It is based on a FreeDOS kernel ported to modern C++.


In short, FreeDOS plus-plus.



Can be compiled with clang (not gcc!) and booted under

[dosemu2](https://github.com/dosemu2/dosemu2).



## building and installing

Run `./configure.meson []`.


This creates and configures the build dir and prints

the instructions for the further build steps. It should also inform

you about any missing build-dependencies, which you need to install.



## installing from pre-built package

For the ubuntu package please visit

[this PPA](https://code.launchpad.net/~dosemu2/+archive/ubuntu/ppa).

Fedora packages are

[here](https://copr.fedorainfracloud.org/coprs/stsp/dosemu2).

OpenSUSE packages are

[here](https://download.opensuse.org/repositories/home:/stsp2/openSUSE_Tumbleweed).



## running

The simplest way to get it running is to use

[dosemu2](https://github.com/dosemu2/dosemu2).


Get the pre-built dosemu2 packages from

[ubuntu PPA](https://code.launchpad.net/~dosemu2/+archive/ubuntu/ppa)

or from

[COPR repo](https://copr.fedorainfracloud.org/coprs/stsp/dosemu2)

or from

[OpenSUSE repo](https://download.opensuse.org/repositories/home:/stsp2/openSUSE_Tumbleweed)

or build it from

[sources](https://github.com/dosemu2/dosemu2).



## configuration

fdpp uses fdppconf.sys file at boot. This file has

the standard format of config.sys with some syntax

extensions. It is fully backward-compatible with the

DOSish config.sys, and if fdppconf.sys is missing,

config.sys is attempted instead.



## but what it *actually* is? why dosemu2?

fdpp is a user-space library that, as any DOS, can

run DOS programs. Being a library, it can't act on

its own and needs a host program to operate. This

also means it can't be booted from the bare-metal

PC, as the original freedos could.


The host program needs to provide a couple of

call-backs for running real-mode code in v86 or

similar environment. See

[this code](https://github.com/stsp/dosemu2/blob/devel/src/plugin/fdpp/fdpp.c)

as an example of providing call-backs to fdpp, and

[this code](https://github.com/stsp/dosemu2/blob/devel/src/plugin/fdpp/boot.c)

as an example of the boot loader.

Sufficiently DOS-oriented kernels like

[freedos-32](http://freedos-32.sourceforge.net/)

or

[pdos/386](http://pdos.sourceforge.net/)

are the good candidates for running fdpp in the future.



## what fdpp technically is?

A meta-compiler that was initially able to compile the

freedos kernel from its almost unmodified sources.

As the project evolves, the ability to compile freedos

from the unmodified sources have lost its value and was

dropped, as our copy of freedos is now heavily modified.

As the result, the compiler is very small and is targeted

only to our coding patterns.


The main tasks of it are to parse FAR pointers and generate

thunks to real-mode asm code of freedos. As with any other

compiler, fdpp is supplied with a small runtime support

library and a dynamic linker.



## compatibility

Simply put, fdpp runs every DOS program we tried, so the

compatibility level is supposed to be very high. Better

than that of most other known DOS clones, including FreeDOS.


If you find some compatibility problems, please

[report a bug](https://github.com/dosemu2/fdpp/issues).



## portability

fdpp can work in any environment with STL/C++ runtime & minimal

posix support.

The build requirements are in line with today's posix-compatible

environments: you'll need the full stack of tools like bison,

autoconf, sed etc. Additionally you'll need a clang tool-chain

as clang++ is the only compiler to build fdpp with. That said,

building fdpp under itself may be a challenge. :)



## related projects

### FreeDOS

[FreeDOS kernel](http://www.fdos.org/kernel/) is a

DOS-compatible kernel that is used as a core of fdpp.



### dosemu2

[dosemu2](https://github.com/dosemu2/dosemu2)

is a virtual machine that allows you to run DOS software under linux.

It is a primary host platform for fdpp.



## similar projects

### dosbox

[dosbox](https://www.dosbox.com/) has a good

[built-in DOS](https://sourceforge.net/p/dosbox/code-0/HEAD/tree/dosbox/trunk/src/dos/)

written in C++. It is tightly coupled to dosbox; you can't

easily port it to your project, whereas fdpp is designed to

be plugable. Also it uses host APIs and libraries for

filesystem access, CD-ROM playing and similar things. fdpp

uses no host APIs or libraries, which may be good or bad,

depending on your use-case. dosbox is cleanly written in C++,

whereas fdpp wraps the C-coded freedos kernel into a C++ framework,

resulting in a nuclear C/C++ mix.



### freedos-32 (inactive)

[freedos-32](http://freedos-32.sourceforge.net/) is a

kernel written with DOS compatibility in mind. It has a

rich user-space part with libc. Very good candidate for

running fdpp. Unfortunately,

[the kernel](https://sourceforge.net/p/freedos-32/code/HEAD/tree/trunk/)

was scrapped, and currently

[something else](https://github.com/salvois/kernel)

is being developed.



### NightKernel

[NightKernel](https://github.com/mercury0x000d/NightKernel)

is `A 32-bit drop-in replacement for the FreeDOS kernel`, as

they call themselves. In fact, it is an assembly-written

ring-0 kernel, currently w/o any DOS compatibility at all.

Can't be used to run fdpp because it doesn't support user-space

add-ons.



### PDOS/386

[pdos/386](http://pdos.sourceforge.net/)

is a Public Domain Operating System with a user interface as simple

as MSDOS.

It supports a "theoretical 32-bit MSDOS API" (probably similar to

that of 32-bit DOS extenders) and some of the Win32 API, allowing

a subset of Windows executables to be run. PDOS/386 is good enough to

run gcc, as, and ld to rebuild itself.


As for running fdpp - pdos/386 is a very promising project, but

its author seems to be reluctant at adding v86 support, preferring

to switch to real mode for bios calls. The lack of v86 leaves very

small room for fdpp and for DOS programs in general unfortunately.