QuickBasic compiler clone

This is a DEVELOPMENT PROJECT. It is NOT A FINISHED PRODUCT.

Purpose is to provide tools for running QuickBASIC programs in Linux and other non-MS-DOS -environments.

It currently seems like it will become a QuickBASIC to C++ translator. In fact, it already translates a large subset of QuickBASIC to C++. However, the resulting code is not maintainable, and the library which it requires, is not finished. But it is being developed, in hopes it will one day enable running complicated DOS-specific QuickBASIC programs such as this, under Linux.

• Compiler is almost finished.
• Runtime library implementation has been started.

These features are often missing from other BASIC implementations, because they are difficult to implement or not seemed as important.

• ON n GOTO/GOSUB
• READ/DATA/RESTORE
• Fully compatible INKEY$
• TIMER function
• Type compatibility (INTEGER must still be 16-bit signed integer etc)
• PLAY/ON PLAY
• DEF FN
• Number printing and stringifying (PRINT, STR$) compatibility (spaces!)
• OPEN: Both syntaxes
• NEXT with comma separated list of variables
• IF: Both syntaxes plus implicit GOTO in THEN and ELSE support.
• PRINT abbreviated as ? support
• String constant shortcut syntax (from GW-BASIC): closing " is not required, newline terminates
• PRINT syntax shortcut (from GW-BASIC): parameters do not need to be separated by ;

Some of these features require emulation of PC-style hardware without direct hardware access.

• DEF SEG &HB800/PEEK/POKE support for direct video access in text mode
• IN/OUT support to ports &H388 - &H389 for AdLib support
• SCREEN 12/13, PSET and other drawing stuff

These QuickBASIC features are not seen as important, and will not be supported (unless somebody has too much time).

• All the excessive ERR codes like "String formula too complex" etc
• KEY ON/KEY OFF (dunno about ON KEY)
• FIELD and other obscure file features (some of which were new in QB 7.0)
• COMMON, CHAIN

In modern operating systems, the memory allocation is designed so that the user doesn't have to care about it. We don't have to meddle with EMS/XMS or any other kind of perverse system the hardware requires for memory allocation.
So if you want to say DIM area(1048576) AS INTEGER, it's fine!
Things like VARPTR$ and SADD() will have to be adjusted a bit though.

In *nix systems, all the devices have been designed so that you can use them by just opening the appropriate file from /dev directory. For example, if you wanted to record and play with your soundcard, you could do OPEN "/dev/dsp" FOR BINARY AS #1, and that's fine. You read there (record), you write there (play).
Of course this won't work in Windows systems.
Other examples could be floppy disks, frame buffer consoles etc.
This isn't the whole truth. Some devices require you to do ioctls before you can do anything useful. This will be considered.

There are no plans for extra features yet, but internationalizations like UTF-8 support would be nice.

QuickBasic programs are usually designed to take 100% of the CPU time all the time. This badly fits to multitasking environments we nowadays have in modern operating systems.
But history is history, and we have to support it.
But we don't have to limit ourselves to it. Even if we couldn't detect and convert Ti#=TIMER:WHILE TIMER<Ti#+1:WEND style loops to USLEEP 1000000, we could support things like USLEEP and FORK. Just maybe.
See your favourite POSIX manual if you don't know what those functions mean.

The ON PLAY(n) mechanism (and ON KEY(n), and ON TIMER(n), and ON STRIG(n), and ON PEN, and ON COM(n)) could also be implemented as threads. That way, we wouldn't need to prefix each statement with a call to a checking routine as is done by QuicBASIC. (We still need to do that for ON ERROR, though, because of RESUME which may require repeating the same statement.)

qbc has been written by Joel Yliluoma, a.k.a. Bisqwit,
and is distributed under the terms of the General Public License (GPL).

Extensive documentation of the design of this compiler can be found in the source package in the doc/ directory.

At least these GNU tools are required: flex, gcc, make.
It also utilizes clamp (C++ lambda preprocessor), but it is included in the archive.
boost::regex and boost::smart_ptr are also required.

Then learn programming. It's a slow journey which requires patience and eagerness to learn new things.

If you want to start programming with BASIC, go and see DarkBasic.

The official home page of qbc is at http://iki.fi/bisqwit/source/qbc.html.
Check there for new versions.