At first glance

HackRF

The original HackRF code can be found at /hackrf, it is a subproject inside the source code. It points to https://github.com/mossmann/hackrf

Portapack

The rest of the code, including the portapack and havoc/mayhem extras can be found at /firmware

The portapack <--> HackRF interface functions are located in /firmware/baseband

There is an underlying OS framework, the CHIBIOS/RT, which is located at /firmware/chibios for the abstract functionality, and /firmware/chibios-portapack for the specific portapack board hardware drivers and configurations.

Application folder

The portapack application software, can be found at /firmware/application

User interface: /firmware/application/ui

Apps (options in each menu): /firmware/application/apps

IC / hardware components interface: /firmware/application/hw

Common protocols functionality: /firmware/application/protocols

User Interface

Menus and Widgets

MOST menus (excluding OPTIONS and DEBUG, which are actually apps) and pop-up boxes (yes/no, yes/cancel, ok) are defined in /firmware/application/ui_navigation.cpp

The Options menu is actually an "app" defined at /firmware/application/apps/ui_settings.cpp

The Debug menu (also an app) is defined at /firmware/application/apps/ui_debug.cpp

The widgets used in the UI, as buttons, texts, checkboxes, input fields, etc. are to be found at /firmware/common/ui_widget.cpp