libfdt is an open-source library released under the BSD license:

libfdt - Flat Device Tree manipulation

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libfdt allows flattened device trees to be represented as a
"blob", which is a compact flattened format. This is useful,
particularly for embedded systems, such as ARM, because it
allows many different devices to be included in a single binary
allowing for a high level of portability.

The source and more information about the library can be found
here:

http://www.denx.de/wiki/U-Boot/UBootFdtInfo

1) D. Gibson, B. Herrenschmidt. Device trees everywhere. 2006.
http://ozlabs.org/~dgibson/papers/dtc-paper.pdf