NAME

Language::Befunge - a Befunge-98 interpreter

SYNOPSIS

    use Language::Befunge;
    my $interp = Language::Befunge->new( { file => 'program.bf' } );
    $interp->run_code( "param", 7, "foo" );

    Or, one can write directly:
    my $interp = Language::Befunge->new;
    $interp->store_code( <<'END_OF_CODE' );
    < @,,,,"foo"a
    END_OF_CODE
    $interp->run_code;

DESCRIPTION

Enter the realm of topological languages!

This module implements the Funge-98 specifications on a 2D field (also called Befunge). It can also work as a Trefunge implementation (3D).

This Befunge-98 interpreters assumes the stack and Funge-Space cells of this implementation are 32 bits signed integers (I hope your os understand those integers). This means that the torus (or Cartesian Lahey-Space topology to be more precise) looks like the following:

              32-bit Befunge-98
              =================
                      ^
                      |-2,147,483,648
                      |
                      |         x
          <-----------+----------->
  -2,147,483,648      |      2,147,483,647
                      |
                     y|2,147,483,647
                      v

This implementation is meant to work on unix-like systems, because this interpreters only handle the character which ordinal value is 10 (also known as \n) as an End-Of-Line chars. In particular, no warranty is made neither for Microsoft systems (\r\n) nor for Macs (\r).

This module also implements the Concurrent Funge semantics.

PUBLIC METHODS

new( [params] )

Call directly the Language::Befunge::Interpreter constructor. Refer to Language::Befunge::Interpreter for more information.

TODO

o

Write standard libraries.

BUGS

Although this module comes with a full set of tests, maybe there are subtle bugs - or maybe even I misinterpreted the Funge-98 specs. Please report them to me.

There are some bugs anyway, but they come from the specs:

o

About the 18th cell pushed by the y instruction: Funge specs just tell to push onto the stack the size of the stacks, but nothing is said about how user will retrieve the number of stacks.

o

About the load semantics. Once a library is loaded, the interpreter is to put onto the TOSS the fingerprint of the just-loaded library. But nothing is said if the fingerprint is bigger than the maximum cell width (here, 4 bytes). This means that libraries can't have a name bigger than 0x80000000, ie, more than four letters with the first one smaller than P (chr(80)).

Since perl is not so rigid, one can build libraries with more than four letters, but perl will issue a warning about non-portability of numbers greater than 0xffffffff.

ACKNOWLEDGEMENTS

I would like to thank Chris Pressey, creator of Befunge, who gave a whole new dimension to both coding and obfuscating.

SEE ALSO

perl

http://www.catseye.mb.ca/esoteric/befunge/

http://dufflebunk.iwarp.com/JSFunge/spec98.html

AUTHOR

Jerome Quelin, <jquelin@cpan.org>

Development is discussed on <language-befunge@mongueurs.net>

COPYRIGHT & LICENSE

Copyright (c) 2001-2008 Jerome Quelin, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.