Libqrencode is a C library for encoding data in a QR Code symbol, a kind of
2D symbology that can be scanned by handy terminals such as a mobile phone
with CCD. The capacity of QR Code is up to 7000 digits or 4000 characters,
and is highly robustness.

Libqrencode supports QR Code model 2, described in JIS (Japanese Industrial
Standards) X0510:2004 or ISO/IEC 18004. Currently the following features are
not supported:
    * ECI and FNC1 mode
    * QR Code model 1

WWW: http://megaui.net/fukuchi/works/qrencode/index.en.html