px4-firmware/nuttx/lib/termios/lib_cfsetspeed.c

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/****************************************************************************
* lib/termios/lib_cfsetspeed.c
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <sys/types.h>
#include <termios.h>
#include <assert.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: cfsetspeed
*
* Descripton:
* The cfsetspeed() function is a non-POSIX function that sets the baud
* stored in the structure pointed to by termiosp to speed.
*
* There is no effect on the baud set in the hardware until a subsequent
* successful call to tcsetattr() on the same termios structure.
*
* NOTE 1: NuttX does not control input/output baud independently. Both
* must be the same. The POSIX standard interfaces, cfisetispeed() and
* cfisetospeed() are defined to be cfsetspeed() in termios.h.
*
* NOTE 3: A consequence of NOTE 1 is that you should never attempt to
* set the input and output baud to different values.
*
* Also, the following POSIX requirement cannot be supported: "If the input
* baud rate stored in the termios structure pointed to by termios_p is 0,
* the input baud rate given to the hardware will be the same as the output
* baud rate stored in the termios structure."
*
* NOTE 2. In Nuttx, the speed_t is defined to be uint32_t and the baud
* encodings of termios.h are the actual baud values themselves. Therefore,
* any baud value can be provided as the speed argument here. However, if
* you do so, your code will *NOT* be portable to other environments where
* speed_t is smaller and where the termios.h baud values are encoded! To
* avoid portability issues, use the baud definitions in termios.h!
*
* Linux, for example, would require this (also non-portable) sequence:
*
* cfsetispeed(termiosp, BOTHER);
* termiosp->c_ispeed = baud;
*
* cfsetospeed(termiosp, BOTHER);
* termiosp->c_ospeed = baud;
*
* Input Parameters:
* termiosp - The termiosp argument is a pointer to a termios structure.
* speed - The new input speed
*
* Returned Value:
* Baud is not checked... OK is always returned (this is non-standard
* behavior).
*
****************************************************************************/
int cfsetspeed(FAR struct termios *termiosp, speed_t speed)
{
FAR speed_t *speedp;
DEBUGASSERT(termiosp);
speedp = (FAR speed_t *)&termiosp->c_speed;
*speedp = speed;
return OK;
}