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5f138519eb
Add an explicitly numeric interface for baudrate setting. For glibc, this only announces what is a fair accompli, but this is a plausible way forward for standardization, and may be possible to infill on non-compliant systems. The POSIX committee has stated: [https://www.austingroupbugs.net/view.php?id=1916#c7135] A future version of this standard is expected to add at least the following symbolic constants for use as values of objects of type speed_t: B57600, B115200, B230400, B460800, and B921600. Implementations are encouraged to propose additional interfaces which will make it possible to set and query a wider range of speeds than just those enumerated by the constants beginning with B. If a set of common interfaces emerges between several implementations, a future version of this standard will likely add those interfaces. This is exactly that interface. The use of the term "baud" is due to the need to have a term contrasting "speed", and it is already well established as a legacy term -- including in the names of the legacy Bxxx constants. Futhermore, it *is* valid from the point of view that the termios interface fundamentally emulates an RS-232 serial port as far as the application software is concerned. The documentation states that for the current version of glibc, speed_t == baud_t, but explicitly declares that this may not be the case in the future. Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
60 lines
1.9 KiB
C
60 lines
1.9 KiB
C
/* cfsetspeed(), Linux version.
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Copyright (C) 1991-2025 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 <termios_internals.h>
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/* Set both the input and output baud rates stored in *TERMIOS_P to SPEED. */
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int
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__cfsetspeed (struct termios *termios_p, speed_t speed)
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{
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tcflag_t cbaud = ___speed_to_cbaud (speed);
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termios_p->c_ospeed = speed;
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termios_p->c_ispeed = speed;
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termios_p->c_cflag &= ~(CBAUD | CIBAUD);
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termios_p->c_cflag |= cbaud | (cbaud << IBSHIFT);
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return 0;
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}
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libc_hidden_def (__cfsetspeed)
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versioned_symbol (libc, __cfsetspeed, cfsetspeed, GLIBC_2_42);
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#if _TERMIOS_OLD_COMPAT
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int
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attribute_compat_text_section
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__old_cfsetspeed (old_termios_t *termios_p, speed_t speed)
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{
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speed_t real_speed = ___cbaud_to_speed (speed, -1);
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if (real_speed == (speed_t)-1)
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return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
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#if !_HAVE_STRUCT_OLD_TERMIOS
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/* Otherwise these fields don't exist in old_termios_t */
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termios_p->c_ospeed = real_speed;
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termios_p->c_ispeed = real_speed;
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#endif
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termios_p->c_cflag &= ~(CBAUD | CIBAUD);
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termios_p->c_cflag |= speed | (speed << IBSHIFT);
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return 0;
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}
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compat_symbol (libc, __old_cfsetspeed, cfsetspeed, GLIBC_2_0);
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#endif /* _TERMIOS_OLD_COMPAT */
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