Here is a list of all files with brief descriptions:

[detail level 1234]

drivers
crypto
rng90
rng90.c	Implementation of the RNG90 driver functions
rng90.h	Header file with declarations and macros for driving an rng90
hal
avr0
twi
twi.c	Source file with implementation of hardware TWI/I2C functions and macros
twi.h	Header file with declarations and macros for hardware TWI/I2C
common
defines
TWI_defines.h	Macro definitions for TWI/I2C communication flags and operations
enums
TWI_enums.h	Enumerations for TWI/I2C interface modes, operations, acknowledgment, and error codes
utils
crc
crc16.c
crc16.h	Header file with declarations and macros for CRC16 checksum calculation
macros
stringify.h	Helper macros for stringification in C preprocessor
systick
systick.c	Implements the SysTick utility functions
systick.h	Header file with declarations and macros for systick utility