47 lines
1.7 KiB
ReStructuredText
47 lines
1.7 KiB
ReStructuredText
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===============
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NuttX libraries
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===============
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This page discusses the NuttX libraries that can be found in ``libs/``
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Libraries in NuttX are very special creatures. They have these properties:
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1. They can be shared by both application logic and logic within the OS when
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using the FLAT build.
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2. But in PROTECTED and KERNEL modes, they must be built differently: The
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copies used by applications and the OS cannot be the same. Rather,
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separate versions of libraries must be built for the kernel and for
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applications.
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3. When used by the OS, some special care must be taken to assure that the
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OS logic does not disrupt the user's errno value and that the OS does
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not create inappropriate cancellation points.
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For example, ``sem_wait()`` is both a cancellation point and modifies the
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errno value. So within the FLAT build and without kernel version for
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the PROTECTED and KERNEL builds, the special internal OS interface
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``nxsem_wait()`` must be used. Within libraries, the macro ``_SEM_WAIT()``
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(as defined in ``include/nuttx/semaphore.h``) is used instead. The
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definition of this macro accounts for the different usage environments.
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NOTE: The libraries under ``libs/`` build differently from other NuttX
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components: There are no build-related files in the ``libs/`` directory; it
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is simply a container for other well-known, individual library directories.
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The upper level Makefile logic is aware of the libraries within the ``libs/``
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container.
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The only real function of the ``libs/`` directory is to prevent the top-level
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directory from becoming cluttered with individual libraries.
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.. toctree::
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:maxdepth: 1
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:caption: Contents:
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libc/index.rst
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libdsp.rst
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libm.rst
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libxx.rst
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libnx/index.rst
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