$re = '/typedef\s+((?:\w+\s*){1,})\(\*\s*(\w\S+)\s*\)\s*\((.*)\);/m';
$str = 'typedef unsigned long (*genpool_algo_t)(unsigned long *map,unsigned long size,unsigned long start,unsigned int nr,void *data, struct gen_pool *pool, unsigned long start_addr);
typedef void (*xa_update_node_t)(struct xa_node *node);';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php