QuickBasic compiler clone

0. Contents

This is the documentation of qbc-0.1.1.8.

   1. Purpose
   2. Goals
      2.1. Features not omitted
      2.2. Features supported if possible
      2.3. Features not considered to be supported
      2.4. Features which are gained for free
         2.4.1. Memory allocation

         2.4.2. Hardware services
      2.5. Extra features
         2.5.1. Multitasking
   3. Copying
   4. Requirements
   5. "I want to start programming"
   6. Downloading

1. Purpose

Tokenizes and parses QuickBasic code. This is under development.

Latest snapshots of the lexer and parser are available:
qb.l // 2002-04-08 (3 kB)
qb.y // 2002-04-08 (8 kB)

If you are interested in joining the development, please contact me.

2. Goals

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

Several ideas are, what this should become.

Interpreter
Pros:
- Portable
Cons:
- No standalone programs
Compiler / translator, for:
- Assembler
  Pros:
  - Should be fast
  Cons:
  - Restricted to a certain architecture
- To C
  Pros:
  - Should become fast
  - Multi-architecture
  Cons:
  - Most certainly unmaintainable
  - Requires a C compiler
- To Ruby
  Pros:
  - Should be elegant and maintainable
  - Multi-architecture
  Cons:
  - Ruby isn't yet very well-spread

2.1. Features not omitted

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
 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

`2.2. Features supported if possible`



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

`2.3. Features not considered to be supported`



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)

`2.4. Features which are gained for free`

`2.4.1. Memory allocation`



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.

`2.4.2. Hardware services`



In *nix systems, all the devices have been designed so that you
can use them by just opening the appropiate 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.

`2.5. Extra features`



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

`2.5.1. Multitasking`



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.

`3. Copying`



qbc has been written by Joel Yliluoma, a.k.a.
Bisqwit,

and is distributed under the terms of the
General Public License (GPL).

`4. Requirements`



At least these GNU tools are required: flex, bison, gcc, make.

`5. "I want to start programming"`



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.

`6. Downloading`


   The official home page of qbc
   is at http://iki.fi/bisqwit/source/qbc.html.

   Check there for new versions.

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