lib_SRC += lib/stdio.c # I/O library.
lib_SRC += lib/stdlib.c # Utility functions.
lib_SRC += lib/string.c # String functions.
-lib_SRC += lib/arithmetic.c
+lib_SRC += lib/arithmetic.c # 64-bit arithmetic for GCC.
+lib_SRC += lib/ustar.c # Unix standard tar format utilities.
# User level only library code.
lib/user_SRC = lib/user/debug.c # Debug helpers.