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98 lines
3.1 KiB
C
98 lines
3.1 KiB
C
/* `struct termios' speed frobnication functions. Linux version.
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Copyright (C) 1991-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stddef.h>
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#include <errno.h>
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#include <termios.h>
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/* This is a gross hack around a kernel bug. If the cfsetispeed functions
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is called with the SPEED argument set to zero this means use the same
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speed as for output. But we don't have independent input and output
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speeds and therefore cannot record this.
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We use an unused bit in the `c_iflag' field to keep track of this
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use of `cfsetispeed'. The value here must correspond to the one used
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in `tcsetattr.c'. */
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#define IBAUD0 020000000000
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/* Return the output baud rate stored in *TERMIOS_P. */
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speed_t
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cfgetospeed (const struct termios *termios_p)
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{
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return termios_p->c_cflag & (CBAUD | CBAUDEX);
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}
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/* Return the input baud rate stored in *TERMIOS_P.
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Although for Linux there is no difference between input and output
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speed, the numerical 0 is a special case for the input baud rate. It
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should set the input baud rate to the output baud rate. */
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speed_t
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cfgetispeed (const struct termios *termios_p)
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{
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return ((termios_p->c_iflag & IBAUD0)
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? 0 : termios_p->c_cflag & (CBAUD | CBAUDEX));
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}
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/* Set the output baud rate stored in *TERMIOS_P to SPEED. */
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int
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cfsetospeed (struct termios *termios_p, speed_t speed)
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{
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if ((speed & ~CBAUD) != 0
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&& (speed < B57600 || speed > __MAX_BAUD))
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return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
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#if _HAVE_STRUCT_TERMIOS_C_OSPEED
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termios_p->c_ospeed = speed;
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#endif
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termios_p->c_cflag &= ~(CBAUD | CBAUDEX);
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termios_p->c_cflag |= speed;
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return 0;
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}
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libc_hidden_def (cfsetospeed)
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/* Set the input baud rate stored in *TERMIOS_P to SPEED.
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Although for Linux there is no difference between input and output
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speed, the numerical 0 is a special case for the input baud rate. It
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should set the input baud rate to the output baud rate. */
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int
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cfsetispeed (struct termios *termios_p, speed_t speed)
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{
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if ((speed & ~CBAUD) != 0
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&& (speed < B57600 || speed > __MAX_BAUD))
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return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
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#if _HAVE_STRUCT_TERMIOS_C_ISPEED
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termios_p->c_ispeed = speed;
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#endif
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if (speed == 0)
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termios_p->c_iflag |= IBAUD0;
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else
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{
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termios_p->c_iflag &= ~IBAUD0;
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termios_p->c_cflag &= ~(CBAUD | CBAUDEX);
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termios_p->c_cflag |= speed;
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}
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return 0;
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}
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libc_hidden_def (cfsetispeed)
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