.. SPDX-License-Identifier: CC-BY-SA-4.0

.. Copyright (C) 2020, 2021 embedded brains GmbH (http://www.embedded-brains.de)
.. Copyright (C) 2015 On-Line Applications Research Corporation (OAR)

.. This file is part of the RTEMS quality process and was automatically
.. generated.  If you find something that needs to be fixed or
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..
.. https://www.rtems.org/bugs.html
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.. Generated from spec:/rtems/io/if/group-3

.. _KernelCharacterIOSupportIntroduction:

Introduction
============

.. The following list was generated from:
.. spec:/rtems/io/if/putc
.. spec:/rtems/io/if/put-char
.. spec:/rtems/io/if/putk
.. spec:/rtems/io/if/printk
.. spec:/rtems/io/if/vprintk
.. spec:/rtems/io/if/printk-printer
.. spec:/rtems/io/if/getchark

The kernel character input/output support is an extension of the
:ref:`RTEMSAPIClassicIO` to output characters to the kernel character output
device and receive characters from the kernel character input device using a
polled and non-blocking implementation.

The directives may be used to print debug and test information.  The kernel
character input/output support should work even if no Console Driver is
configured, see :ref:`CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER`.  The kernel
character input and output device is provided by the :term:`BSP`. Applications
may change the device. The directives provided by the Kernel Character I/O
Support are:

* :ref:`InterfaceRtemsPutc` - Outputs the character to the kernel character
  output device.

* :ref:`InterfaceRtemsPutChar` - Puts the character using
  :ref:`InterfaceRtemsPutc`

* :ref:`InterfacePutk` - Outputs the characters of the string and a newline
  character to the kernel character output device.

* :ref:`InterfacePrintk` - Outputs the characters defined by the format string
  and the arguments to the kernel character output device.

* :ref:`InterfaceVprintk` - Outputs the characters defined by the format string
  and the variable argument list to the kernel character output device.

* :ref:`InterfaceRtemsPrintkPrinter` - Outputs the characters defined by the
  format string and the variable argument list to the kernel character output
  device.

* :ref:`InterfaceGetchark` - Tries to dequeue a character from the kernel
  character input device.