                    =====================================
                      Package "Bit::Vector" Version 5.8
                    =====================================


This package is available for download either from my web site at

                  http://www.engelschall.com/u/sb/download/

or from any CPAN (= "Comprehensive Perl Archive Network") mirror server:

               http://www.perl.com/CPAN/authors/id/S/ST/STBEY/


Abstract:
---------

Bit::Vector is an efficient C library which allows you to handle
bit vectors, sets (of integers), "big integer arithmetic" and
boolean matrices, all of arbitrary sizes.

The library is efficient (in terms of algorithmical complexity)
and therefore fast (in terms of execution speed) for instance
through the widespread use of divide-and-conquer algorithms.

The package also includes an object-oriented Perl module for
accessing the C library from Perl, and features overloaded
operators for maximum ease of use.

The C library can nevertheless be used stand-alone, without Perl.


Legal issues:
-------------

This package with all its parts is

Copyright (c) 1995 - 2000 by Steffen Beyer.
All rights reserved.

This package is free software; you can use, modify and redistribute
it under the same terms as Perl itself, i.e., under the terms of
the "Artistic License" or the "GNU General Public License".

The C library at the core of this Perl module can additionally
be used, modified and redistributed under the terms of the
"GNU Library General Public License".

Please refer to the files "Artistic.txt", "GNU_GPL.txt" and
"GNU_LGPL.txt" in this distribution, respectively, for details!


Prerequisites:
--------------

Perl version 5.000 or higher, and an ANSI C compiler (!)
                                     ^^^^^^


Installation:
-------------

Please see the file "INSTALL.txt" in this distribution for instructions
on how to install this package.

It is essential that you read this file since one of the special cases
described in it might apply to you, especially if you are running Perl
under Windows.


Changes over previous versions:
-------------------------------

Please refer to the file "CHANGES.txt" in this distribution for a detailed
version history.


Documentation:
--------------

The documentation of this package is included in POD format (= "Plain
Old Documentation") in the file "Vector.pod" in this distribution,
the human-readable markup-language standard for Perl documentation.

By building this package, this documentation will automatically be
converted into a man page, which will automatically be installed in
your Perl tree for further reference through the installation process,
where it can be accessed by the commands "man Bit::Vector" (UNIX)
and "perldoc Bit::Vector" (UNIX and Win32).

If Perl is not available on your system, you can also read this file
directly.


What does it do:
----------------

This module is useful for a large range of different tasks:

  -  For example for implementing sets and performing set operations
     (like union, difference, intersection, complement, check for subset
     relationship etc.),

  -  as a basis for many efficient algorithms, for instance the
     "Sieve of Erathostenes" (for calculating prime numbers),

     (The complexities of the methods in this module are usually either
      O(1) or O(n/b), where "b" is the number of bits in a machine word
      on your system.)

  -  for shift registers of arbitrary length (for example for cyclic
     redundancy checksums),

  -  to calculate "look-ahead", "first" and "follow" character sets
     for parsers and compiler-compilers,

  -  for graph algorithms,

  -  for efficient storage and retrieval of status information,

  -  for performing text synthesis ruled by boolean expressions,

  -  for "big integer" arithmetic with arbitrarily large integers,

  -  for manipulations of chunks of bits of arbitrary size,

  -  for bitwise processing of audio CD wave files,

  -  to convert formats of data files,

and more.

(A number of example applications is available from my web site at
http://www.engelschall.com/u/sb/download/.)

A large number of import/export methods allow you to access individual
bits, contiguous ranges of bits, machine words, arbitrary chunks of
bits, lists (arrays) of chunks of bits or machine words and a whole
bit vector at once (for instance for blockwrite/-read to and from
a file).

You can also import and export the contents of a bit vector in binary,
hexadecimal and decimal representation as well as ".newsrc" style
enumerations.

Note that this module is specifically designed for efficiency, which is
also the reason why its methods are implemented in C.

To further increase execution speed, the module doesn't use bytes as its
basic storage unit, but rather uses machine words, assuming that a machine
word is the most efficiently handled size of all scalar types on all
machines (that's what the ANSI C standard proposes and assumes anyway).

In order to achieve this, it automatically determines the number of bits
in a machine word on your system and then adjusts its internal configuration
constants accordingly.

The greater the size of this basic storage unit, the better the complexity
(= execution speed) of the methods in this module, but also the greater the
average waste of unused bits in the last word.

The range of available methods is exceptionally large for this kind of library;
in detail:

Version()                Word_Bits()              Long_Bits()
new()                    new_Hex()                new_Bin()
new_Dec()                new_Enum()               Shadow()
Clone()                  Concat()                 Concat_List()
Size()                   Resize()                 Copy()
Empty()                  Fill()                   Flip()
Primes()                 Reverse()                Interval_Empty()
Interval_Fill()          Interval_Flip()          Interval_Reverse()
Interval_Scan_inc()      Interval_Scan_dec()      Interval_Copy()
Interval_Substitute()    is_empty()               is_full()
equal()                  Lexicompare()            Compare()
to_Hex()                 from_Hex()               to_Bin()
from_Bin()               to_Dec()                 from_Dec()
to_Enum()                from_Enum()              Bit_Off()
Bit_On()                 bit_flip()               bit_test()
Bit_Copy()               LSB()                    MSB()
lsb()                    msb()                    rotate_left()
rotate_right()           shift_left()             shift_right()
Move_Left()              Move_Right()             Insert()
Delete()                 increment()              decrement()
add()                    subtract()               Negate()
Absolute()               Sign()                   Multiply()
Divide()                 GCD()                    Power()
Block_Store()            Block_Read()             Word_Size()
Word_Store()             Word_Read()              Word_List_Store()
Word_List_Read()         Word_Insert()            Word_Delete()
Chunk_Store()            Chunk_Read()             Chunk_List_Store()
Chunk_List_Read()        Index_List_Remove()      Index_List_Store()
Index_List_Read()        Union()                  Intersection()
Difference()             ExclusiveOr()            Complement()
subset()                 Norm()                   Min()
Max()                    Multiplication()         Product()
Closure()                Transpose()


Note to C developers:
---------------------

Note again that the C library at the core of this module can also be
used stand-alone (i.e., it contains no inter-dependencies whatsoever
with Perl).

The library itself consists of three files: "BitVector.c", "BitVector.h"
and "ToolBox.h".

Just compile "BitVector.c" (which automatically includes "ToolBox.h")
and link the resulting output file "BitVector.o" with your application,
which in turn should include "ToolBox.h" and "BitVector.h" (in this order).


Example applications:
---------------------

See the module "Set::IntRange" for an easy-to-use module for sets
of integers of arbitrary ranges.

See the module "Math::MatrixBool" for an efficient implementation
of boolean matrices and boolean matrix operations.

(Both modules are also available from my web site or any CPAN server.)

An application relying crucially on this "Bit::Vector" module is "Slice",
a tool for generating different document versions out of a single
master file, ruled by boolean expressions ("include english version
of text plus examples but not ...").

(See also http://www.engelschall.com/sw/slice/.)

This tool is itself part of another tool, "Website META Language" ("WML"),
which allows you to generate and maintain large web sites.

Among many other features, it allows you to define your own HTML tags which
will be expanded either at generation or at run time, depending on your
choice.

(See also http://www.engelschall.com/sw/wml/.)

Both tools are written by Ralf S. Engelschall.


Credits:
--------

Please refer to the file "CREDITS.txt" in this distribution for a list
of contributors.


Author's note:
--------------

If you have any questions, suggestions or need any assistance, please
let me know!

Please do send feedback, this is essential for improving this module
according to your needs!

I hope you will find this module beneficial.

Yours,
--
  Steffen Beyer <sb@engelschall.com> http://www.engelschall.com/u/sb/
       "There is enough for the need of everyone in this world,
         but not for the greed of everyone." - Mahatma Gandhi
