FriBiDi is a free implementation of the Unicode Bidirectional Algorithm.
You must download and install the FriBiDi package.
This PECL extension is not bundled with PHP. Additional information such as new releases, downloads, source files, maintainer information, and a CHANGELOG, can be located here: http://pecl.php.net/package/fribidi.
In order to use these functions you must compile PHP with Fribidi support by using the --with-fribidi[=DIR] configure option.
Windows users will enable php_fribidi.dll inside of php.ini in order to use these functions. You may download this PECL extensions DLL from the PHP Downloads page or at http://snaps.php.net/.
The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.