Updating unmaintained package

Hello, I am new to this list and don't feel (due to my non-existant C skills) to belong here, but I need a PECL package that is unmaintained and therefore not available for PHP 7: https://pecl.php.net/package/pcsc I tried to compile it and it throws some errors where I feel somewhat confident that I can solve them. It seems like basic syntax changes. E.g. I found out that I had to replace |zend_rsrc_list_entry ||by |||zend_resource ||(following this blog post: http://www.sklar.com/software/php/2015/03/23/converting-a-php-extension-to-php-7/). But there are other errors like "error: expected expression before" when calling ZEND_FETCH_RESOURCE or "error: macro "RETVAL_STRING" passed 2 arguments, but takes just 1". Seem to me like very basic things to solve, but I can't find any reference / manual where I can find the usage of these functions and which parameters the function expects. Can anybody give me some hints where to search for this information? Maybe there is also a migration guide for PHP extensions from PHP 5 to PHP 7 somewhere. Best Regards, Benedikt.