lib
===
This directory contains numerous, small functions typically associated with
what you would expect to find in a standard C library. The sub-directories
in this directory contain standard interface that can be executed by user-
mode programs.
Normally, NuttX is built with no protection and all threads running in kerne-
mode. In that model, there is no real architectural distinction between
what is a kernel-mode program and what is a user-mode program; the system is
more like on multi-threaded program that all runs in kernel-mode.
But if the CONFIG_NUTTX_KERNEL option is selected, NuttX will be built into
distinct user-mode and kernel-mode sections. In that case, most of the
code in the nuttx/ directory will run in kernel-mode with with exceptions
of (1) the user-mode "proxies" found in syscall/proxies, and (2) the
standard C library functions found in this directory. In this build model,
it is critical to separate the user-mode OS interfaces in this way.
Sub-Directories
===============
The files in the lib/ directory are organized (mostly) according which file
in the include/ directory provides the prototype for library functions. So
we have:
libgen - libgen.h
math - math.h and fixedmath.h
mqueue - pthread.h
net - Various network-related header files: netinet/ether.h, arpa/inet.h
pthread - pthread.h
queue - queue.h
sched - sched.h
semaphore - semaphore.h
stdio - stdio.h
stdlib - stdlib.h
string - string.h
time - time.h
unistd - unistd.h
There is also a misc/ subdirectory that contains various internal functions
and interfaces from header files that are too few to warrant their own sub-
directory:
misc - Nonstandard "glue" logic, debug.h, crc32.h, dirent.h
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