PHP sitemap

I need a program that generates a sitemap automatically. It should work like this: Program is in the root, it will read a .txt file that contains a list of directory's (they all will branch from the root) file will be formatted as one directory per line. Program will go through each directry read all files that have the .htm or .html extension. It will then compare each file to a second .txt file that has a list of files not to be displayed. If there is a match do nothing. If no match then display the file name as a link that links to that file. Do for each directory in the root, Should be fairly simple.