Amiga Computing - Commodore Is Awesome

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urse: v1.1
CURSOR takes programs that are
written for the AmigaBASIC interpreter
and turns them into programs
that can be run directly from
al or Workbench.
In doing so it compiles your
BASIC programs into machine
code, which means that the resultant
program will run faster than
the original. Not all the
AmigaBASIC keywords are implemented
in this version, although
most are. For a full list of supported
commands and functions
look at the file Keywords.DOC in
the Cursor drawer.
The best way to use Cursor is to
copy it into the C: directory of your
boot-up disk. If you're still working
from a bog-standard Workbench
disk you'll need to make some
room first by deleting some of the
things you don't use very much.
You must also copy the file
bas_runtimelibrary (in the libs
directory of the cover disk) into the
LIDS: directory of your boot-up
disk. All programs compiled with
Cursor need this library to be present
in IBS:, and so does Cursor
itself. Cursor also needs the four
maths libraries: mathflp.library,
mathtrans,library, mathieeedoubbas.library,
and mathieeedoubtranslibrarv,
which must he in
LIB& or in rom (mathffp.library is
in rom on 500s and 2000s).
Cursor is best operated from the
CLI— although it is quite feasible to
Icola it if you want — by supplying
the name of the BASIC program as
the parameter. If Cursor finds no
errors it will create an executable
file whose name is that of the
source file without its extension.
If you boot from the cover disk
you will be able to play with
Cursor straight away because
everything is where it should be.
After the cover disk has booted
drag the al window up to the top
of the screen and open it to its full
62 AMIGA COMPUTING November 19g0
height. Then type:
cd cursor
to get into the Cursor directory. If
you're curious, use Dir to see what
files are there, You'll see a few
example programs with litAS
extensions, The one we're going to
use displays a list of prime numbers.
So type:
copy prises.bas ram:
You can work from floppy if you
want, but it's quicker from ram.
Now we've got our BASIC program
where we want it, type:
Cursor racprines.bas
Cursor will load and decrunch,
then a copyright message will
appear followed by the filename
ramprimes•bas automatically supplying
itself to the prompt. The
compiler will then make two
passes of the source code and create
the program.
It takes just a few seconds.
When it's finished type:
dir ran:
and you'll see three things. Firstly
there is a I directory. While it is
working the compiler writes some
temporary files into T:, so it is best
to assign it to the ram disk. The
cover disk startup- sequence has
done this for you.
Next there is the primes,bas file
we copied to ram, and lastly the
program Cursor has created, called
primes. To rim it type:
ran:primes
A window will open and lots of
numbers will scroll past. all the
prime numbers between 2 and
1,000 in fact. To finish the program
at any time, click the window's
close gadget.
Not very impressed, are you?
Well, Primes is just a simple program
to prove that it works. Now
you've successfully compiled
something small, go ahead and
compile a more complicated program,
ManSing.BAS, which is a
Mandelbrot Set image generator.
Although the compiled ManSing
may appear to take an age to draw
its image (about 40 minutes), the
same thing running under
AmigaBASIC takes hours and
hours and hourzzz...
It is important to remember that
you can only compile BASIC
source files which have been saved
in Ascii format, so make sure you
use SAVE "filename", A in the
AmigaBASIC interpreter else you'll
be getting compiler error messages.
If you run Cursor without a filename
as a parameter and press
Return when asked for the name of
the source file, you can change
some options which influence the
compiled programs. Actually, you
can do this either in the menu that
appears when you press Return
after you have started Cursor, or
with the OPTION keyword in the
source file. The following options
are available:
NO WINDOW: No window is
opened automatically when the
compiled program is started.
TRYCLIWINDOW: The compiled
program will try to use the CU
window as a window with the
number I.
If this is not passible — for example,
if the compiled program was
started from Workbench — a new
window is opened. You should not
use graphics commands in the al
window because you can inadvertently
overwrite the windove's border,
OPENWINDOW: A new window
with the number I is always
opened on the Workbench. This is
the default option.
ALLPCRELATIVE: Cursor assumes
that all branches in the compiled
machine code program do not
reach further than 32k. The compiled
program will be shorter if
you use this option.
SOMEPCRELATIVE: Cursor only
assumes that all branches within
subprograms do not reach further
than 32k.
NOPCRELATIVE: All branches can
reach as far as they want. This is
the default option because it is the
safest assumption.
WRITELINENUMBERS: The line
numbers of the source file are written
into the compiled programs.
They will be displayed if the compiled
program aborts with an error
message. But the compiled program
will also get bigger and run
slower.
All programs compiled by
Cursor are pure. and Cursor sets
the pure bit of the programs automatically.
Compiled programs can be
started from the CU or the
Workbench (provide your own tool
icons).
Parameters passed from the al
are treated as if the user typed
them in using the keyboard after
the program has started, separating
them with the Return key, so they
can be read and processed with
INPUT statements.
If an error occurs while a compiled
program is running, an error
message will be written either to
standard output (if it exists) or a
requester will appear.
You will see additional pieces of
information in the requester, like a
more exact description of an I/O
error or perhaps the number of the
line in the source file where the
error occurred.