Write a PHP function in C

Hi, sometimes I miss some functions in PHP. Most of the times I write this function in PHP and put this function(s) in a extra file and include this file in every project I have. Now I want to write those functions I have collected over years in C. 1. for training 2. that i don't need to include my files where my functions are in every time. 3. for more performance? So - how can I do this? I have good C/C++ knowledges. I had a look at google, the PHP site and at the source code of PHP - but I found nothing. I am looking for a little HowTo/Tutorial how am I able to add new features to PHP - perhaps as a module (dont know if it is possible) or as a lib or as something else.. .:) Greets and TIA Christian