==========================================================
      A couple of tips about library's configuration
==========================================================

===============
Error handling
===============

Each public function has a sort of barrier checking that's
to say a set of checks to prevent inconsistences, that may
bring/lead to unsafe operations. If this barrier is passed
we're reasonable sure that operations will be performed on
safe arguments. Actually, this way of proceeding is pretty
simple but efficacious ('keep it simple' philosophy).

This library provides 2 basic methods for handling errors
when some barrier check is not passed:

1- the first one uses an assertion-based layout: when a
   certain condition is not satisfied -- i.e a function
   requires to operate on an undefined list -- then the
   failure of the condition is immediately fatal to the
   main program.

2- the second one uses a 'warning-based' layout: when a
   certain condition isn't satisfied, a warning message
   is printed to <stderr> and a return, from func where
   error occured, is done. It is also possible to avoid
   displaying warning errors by:

   ./configure --disable-warnings

Internally, the library recognizes two main categories
of errors:

   *) memory allocation errors
   *) data errors (all other errors)

For each type of error is possible to "declare" how it
should be handled - using warnings or assertions?!
By default:

   /* print a warning on data error */
   # define CHECK_DATA_WARN_ON_ERROR

   /* exit on memory eror */
   # define CHECK_MEMO_EXIT_ON_ERROR

'include/private/skl_defs.h' is the file where these
macros can be found and modified.


==============
Thread-safety
==============

Basically, this library handles concurrent operations
at two levels, both selectable by using the 'configure'
script (note that these levels are mutually exclusive)

The first level (basic):

   --enable-thread-safety

may be used when you are requested to run concurrent
operations on not shared objects. For example:

   MySKLinsertAD( l1, ... );
   MySKLinsertND( l2, ... );

The second level (full):

   --enable-thread-safety-full

is to be used when concurrent operations on the same
objects may occur. For example:

   MySKLinsertAD( l, ... );
   MySKLinsertND( l, ... );

As far as the library performances, doing a comparison
with a no thread-safe instance of the library, we can
state that, while the first level of thread-safety has
almost a negligible effect on the library performances,
the second one affects the execution time in a more
noticeable way. Anyway, if parallel operations are not
required, a 'no thread-safe' compilation is preferable.


=======================
Node's level generator
=======================

Skiplists are based on a node's level distribution as
balanced as possible. This library tries to achieve it
in two ways: using a pseudo-random number generator or
an alternative (not pseudo-random) implementation. The
second one seems to be a little bit faster, but is not
chosen as default ('include/private/skl_defs.h')


===============
Debug handling
===============

This library uses the Fred Fish's debug library. That one
helps tracing and profiling internal library's operations
<MySKLverboseEnable()> function.
For stopping the verbosity introduced by the dbug library,
it is sufficient to call the func <MySKLverboseDisable()>.
Finally, the way to disable the debug system at all is to
decomment the line below in 'include/private/skl_defs.h':

   # define DBUG_OFF

Note that this macro also disable the two functions that
have been above-mentioned.


===================
Double linked list
===================

It is possible to enable the support for double linked
list. It is better not to do that if not really needed,
since the amount of memory being used is greater - just
an obvious thing - and also a reduction in performance
occurs. If support is needed, it's sufficient to use the
macro below in 'include/private/skl_defs.h':

   # define MYSKL_DOUBLE_LL_TYPE

Enabling double linked list also enables the function
MySKLgetPrevNode()



==========================================================
                     How to install
==========================================================

======================
QUICK INSTALL -- LINUX
======================

If you are using sources from the project's subversion
repository, run 'make -f Makefile.cvs' to generate all
the required configuration scripts. Otherwise, you can
skip this step.

Then the fastest and easiest way to install this library
is the familar:

$ ./configure
$ make
$ make install

For further informations about installing the library,
see the 'INSTALL' file and/or type:

$ ./configure --help

The installation will create some executable files in
the directory './test'. The file 'mysklthreadtest' is
created only if the lib has been compiled with a full
thread support (--enable-thread-safety-full).


=======================
QUICK INSTALL - WINDOWS
=======================

Using Cygwin or MinGW is possible to compile an instance
of this library, following the same steps as those above
for Linux.



==========================================================
                     How to use
==========================================================

Take a look at the main header file <include/myskl.h> and
at the files in the </test> directory.