I'd like to try and write emacs mode for pascal language, as an exercise. There are some significant improvements to default pascal-mode that could be made, for example font-lock for variable declarations and type definitions, and better indentation rules. However, the style of pascal-mode.el is very different from for example cc-mode.el. It seems like in pascal-mode font-locking works simply on pascal keywords, and I don't see a way to implement the features I want by simple edits. cc-mode.el, on the other hand, is hard for me to understand at this point, and reading it line by line is painful.
Are there any tutorials, howtos, or other resources describing common approach to writing language modes? Do I need to read some entry-level guide first, beside emacs and elisp info files? Where should I look for help if I have some specific questions later?