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/* isatty-uart.c. Implementation of the _isatty syscall for newlib with UART
 
   Copyright (C) 2004, Jacob Bower
   Copyright (C) 2010, Embecosm Limited <info@embecosm.com>
 
   Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>
 
   This file is part of Newlib.
 
   The original work by Jacob Bower is provided as-is without any kind of
   warranty. Use it at your own risk!
 
   All subsequent work is bound by version 3 of the GPL as follows.
 
   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the Free
   Software Foundation; either version 3 of the License, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   more details.
 
   You should have received a copy of the GNU General Public License along
   with this program.  If not, see <http:#www.gnu.org/licenses/>.             */
/* -------------------------------------------------------------------------- */
/* This program is commented throughout in a fashion suitable for processing
   with Doxygen.                                                              */
/* -------------------------------------------------------------------------- */
 
#include <errno.h>
#include <unistd.h>
 
 
#undef ERRNO
extern int  errno;
 
 
/* -------------------------------------------------------------------------- */
/*!Is a file a TTY when using a UART?
 
   We only support stdin, stdout and stderr to the console, so we are always a
   TTY for these.
 
   Remember that this function is *not* reentrant, so no static state should
   be held.
 
   @param[in] file  The fileno to check.
 
   @return  1 if we are a TTY, 0 otherwise, with an error code in the global
            variable errno.                                                   */
/* -------------------------------------------------------------------------- */
int
_isatty (int   file)
{
  if ((file == STDIN_FILENO)  ||
      (file == STDOUT_FILENO) ||
      (file == STDERR_FILENO))
    {
      return  1;
    }
  else
    {
      errno = EBADF;
      return  -1;
    }
}	/* _isatty () */