Dependencies on the external libraries
======================================

Ling requires the following libraries:

1. lwIP (TCP/IP networking)
2. Nettle (Low-level crypto)
3. PCRE (Regular expressions)

The dependency on the external libraries is minimized. Only the portion of the
Nettle library that does not use bignums is imported. lwIP and PCRE are
imported almost fully.

How to obtain and build the libraries
=====================================

1. lwIP
-------

Ling is using the current development branch of lwIP. The source code was
obtained from a Git repo at git://git.savannah.nongnu.org/lwip.git and
incorporated into Ling sources. There are multiple changes to lwIP sources
almost exclusively related to debug/error messages. A few files were added under
lib/lwip/ling directory.

Use 'make' or 'make -C lib/lwip' to build the library.

2. Nettle
---------

Nettle should be obtained from a Git repo:

git clone git://git.lysator.liu.se/nettle/nettle.git

To configure the library use the following command:

./configure --disable-public-key --disable-shared --disable-pic --disable-openssl

Use 'make' to build libnettle.a.
Use 'sudo make install' to install the library.

3. PCRE
-------

Ling uses a particular version of PCRE - 7.6. Obtain the library from
http://sourceforge.net/projects/pcre/files/pcre/7.6/pcre-7.6.tar.gz/download.

ATTENTION. Copy pcre_assert.h file to pcre directory as assert.h.
	Copy pcre_globals.c file to pcre directory.

Now build it using the following commands:

./configure --disable-shared --disable-cpp --disable-stack-for-recursion --enable-utf8
				--enable-unicode-properties CFLAGS=-O2 --no-recursion

Then 'make' the library.