nuttx

History

Nathan Hartman 409e2f3701 drivers/serial, libc/termios: Implement tcsendbreak The TERMIOS(3) function tcsendbreak() and the IOCTLs TCSBRK and TCSBRKP transmit a serial line Break. Previously NuttX included an extern declaration for tcsendbreak() and defines for TCSBRK and TCSBRKP but none of these were implemented. Attempting to build programs that called tcsendbreak() would fail with a linker error; attempting to use TCSBRK and TCSBRKP would result in an error at runtime. This changeset adds the tcsendbreak() function and handling for TCSBRK and TCSBRKP; tcsendbreak() is implemented in terms of TCSBRK. Both TCSBRK and TCSBRKP are implemented in terms of the BSD-compatible Break IOCTLs TIOCSBRK and TIOCCBRK, which must be provided by the lower half serial driver. Currently, not all lower half serial drivers in NuttX support these IOCTLs. Those that do implement them may need one or more Kconfig options to be set, such as `CONFIG__U[S]ART_BREAKS` and, on some architectures, a separate `CONFIG__SERIALBRK_BSDCOMPAT`. * drivers/serial/serial.c (uart_tcsendbreak): New function. (uart_ioctl): Implement TCSBRK and TCSBRKP. * libs/libc/termios/lib_tcsendbreak.c (): New file. * libs/libc/termios/Make.defs (CSRCS): Add lib_tcsendbreak.c to the build. Thanks to Xiang Xiao for PR feedback. Co-authored-by: Xiang Xiao <xiaoxiang781216@gmail.com>		2023-02-15 07:50:02 +08:00
..
libc	drivers/serial, libc/termios: Implement tcsendbreak	2023-02-15 07:50:02 +08:00
libdsp	nuttx: unify MIN, MAX and ABS macro definition across the code	2022-12-21 09:31:28 +08:00
libnx	tools: replace INCDIR to Makefile variable	2022-11-03 19:59:55 +08:00
libxx	Minor style clean up	2023-01-28 19:53:20 +02:00
README.txt

README.txt

README
======

This directory holds NuttX libraries.  Libraries in NuttX are very special
creatures.  They have these properties:

1. They can be shared by both application logic and logic within the OS when
   using the FLAT build.

2. But in PROTECTED and KERNEL modes, they must be built differently:  The
   copies used by applications and the OS cannot be the same.  Rather,
   separate versions of libraries must be built for the kernel and for
   applications.

3. When used by the OS, some special care must be taken to assure that the
   OS logic does not disrupt the user's errno value and that the OS does
   not create inappropriate cancellation points.

   For example, sem_wait() is both a cancellation point and modifies the
   errno value.  So within the FLAT build and without kernel version for
   the PROTECTED and KERNEL builds, the special internal OS interface
   nxsem_wait() must be used.  Within libraries, the macro _SEM_WAIT()
   (as defined in include/nuttx/semaphore.h) is used instead.  The
   definition of this macro accounts for the different usage environments.

NOTE:  The libraries under libs/ build differently from other NuttX
components:  There are no build-related files in the libs/ directory; it
is simply a container for other well-known, individual library directories.
The upper level Makefile logic is aware of the libraries within the libs/
container.

The only real function of the libs/ directory is to prevent the top-level
directory from becoming cluttered with individual libraries.