This directory contains:

• Tools to build Phalcon extension from source - they are located in the current directory
• Copied, merged and optimized Phalcon source files, which are used during the build - they are located in <php-version>/safe, <php-version>/32bits and <php-version>/64bits directories
• Resources for build process (config files and source code of build generator) - they are located in _resources directories
• Tool to re-generate copied Phalcon source files according to the main source files - that is gen-build.php script

You can omit this step, if you've got source code for stable Phalcon version. Everything is up-to-date there.

The source code, used to build Phalcon extension, is not the actual code, being developed. When preparing to build Phalcon extension, gen-build.php script needs to be executed. It copies, merges and slightly optimizes all the sources, putting them into <php-version>/safe, <php-version>/32bits and <php-version>/64bits directories.

The algorithm of gen-build.php is as follows:

• Walk through all the code in <phalcon_root>/ext/ directory
• Merge all the found files and copy them into <php-version>/safe directory
• Pre-calculate hashes for 32 bit PHP and 64 bit PHP and put optimized sources into corresponding <php-version>/32bits and <php-version>/64bits directories
• Copy Linux and Windows build configs from to build directories

After those manipulations, any of the build directories contain full code, which can be used to build Phalcon. The differences of the directories are:

• <php-version>/safe directory contain source code to build Phalcon for any PHP - either 32 bit or 64 bit
• <php-version>/32bits directory contain slightly optimized source code to build Phalcon for 32 bit PHP, it will not work properly with 64 bit PHP
• <php-version>/64bits directory contain slightly optimized source code to build Phalcon for 64 bit PHP, it will not work properly with 32 bit PHP

Run gen-build.php, if you're working with development version of Phalcon sources and want to rebuild the extension. Running the tool for stable version of Phalcon sources will not do anything new, because build directories are regenerated by Phalcon team for every stable release.

The tool requires PHP 5.5+ to regenerate <php-version>/safe directory. Additionally, installed Phalcon extension is needed to regenerate <php-version>/32bits and <php-version>/64bits directories.

After running gen-build.php you are ready to build Phalcon extension.

Please, refer to Phalcon documentation

Please, refer to PHP's step by step guide