274 lines
12 KiB
C
274 lines
12 KiB
C
/*
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* Copyright (c) 2006-2021, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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* 2017-08-30 Bernard The first version
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* 2024-04-26 TroyMitchell Add comments for all functions
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/errno.h>
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#include "termios.h"
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#include <rtthread.h>
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/**
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* @brief Gets the current attributes of a terminal device.
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* @param fd File descriptor of the terminal device.
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* @param tio Pointer to a struct termios where the attributes will be stored.
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* @return Upon successful completion, returns 0; otherwise, returns -1.
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*
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* @note This function retrieves the current attributes of a terminal device specified by the file descriptor fd.
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* It uses the ioctl system call with the TCGETA command to obtain the attributes and stores them in the
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* struct termios pointed to by tio.
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* If the ioctl operation fails, the function returns -1 to indicate an error.
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*/
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int tcgetattr(int fd, struct termios *tio)
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{
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/* Get the current serial port settings. */
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if (ioctl(fd, TCGETA, tio))
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return -1;
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return 0;
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}
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/**
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* @brief Sets the attributes of a terminal device.
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* @param fd File descriptor of the terminal device.
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* @param act Action to be taken for the attribute change (TCSANOW, TCSADRAIN, or TCSAFLUSH).
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* @param tio Pointer to a struct termios containing the new attributes.
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* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
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*
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* @note This function sets the attributes of a terminal device specified by the file descriptor fd.
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* The act parameter determines when the attribute change takes effect:
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* - TCSANOW: Make the change immediately.
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* - TCSADRAIN: Make the change after all currently written data has been transmitted.
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* - TCSAFLUSH: Make the change after all currently written data has been transmitted, and discard
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* any received but unread data.
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* The new attributes are specified in the struct termios pointed to by tio.
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* The ioctl system call is used to set the attributes based on the value of act.
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* If the ioctl operation fails or an invalid action is specified, errno is set to indicate the error,
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* and the function returns -1.
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*/
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int tcsetattr(int fd, int act, const struct termios *tio)
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{
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switch (act)
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{
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case TCSANOW:
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/* make the change immediately */
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return (ioctl(fd, TCSETA, (void*)tio));
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case TCSADRAIN:
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/*
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* Don't make the change until all currently written data
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* has been transmitted.
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*/
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return (ioctl(fd, TCSETAW, (void*)tio));
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case TCSAFLUSH:
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/* Don't make the change until all currently written data
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* has been transmitted, at which point any received but
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* unread data is also discarded.
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*/
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return (ioctl(fd, TCSETAF, (void*)tio));
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default:
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errno = EINVAL;
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return (-1);
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}
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}
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/**
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* @brief Gets the session ID of a terminal.
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* @param fd File descriptor of the terminal device.
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* @return Always returns 0.
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*
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* @note This function is a stub and always returns 0.
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* In POSIX systems, tcgetsid() is used to get the session ID of the terminal associated with the file descriptor fd.
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* However, this function does not provide this functionality and simply returns 0 as a placeholder.
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*/
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pid_t tcgetsid(int fd)
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{
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return 0;
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}
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/**
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* @brief Gets the output baud rate from a termios structure.
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* @param tio Pointer to a struct termios containing the terminal attributes.
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* @return Output baud rate extracted from the terminal attributes.
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*
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* @note This function extracts the output baud rate from the termios structure pointed to by tio.
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* It retrieves the baud rate from the c_cflag member of the termios structure using the CBAUD mask.
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* The output baud rate is returned as a speed_t type.
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*/
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speed_t cfgetospeed(const struct termios *tio)
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{
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return tio->c_cflag & CBAUD;
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}
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/**
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* @brief Gets the input baud rate from a termios structure.
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* @param tio Pointer to a struct termios containing the terminal attributes.
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* @return Input baud rate extracted from the terminal attributes.
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*
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* @note This function is a wrapper for the cfgetospeed() function.
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* It returns the input baud rate by calling cfgetospeed() with the termios structure pointer tio.
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*/
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speed_t cfgetispeed(const struct termios *tio)
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{
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return cfgetospeed(tio);
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}
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/**
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* @brief Sets the output baud rate in a termios structure.
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* @param tio Pointer to a struct termios where the output baud rate will be set.
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* @param speed Output baud rate to be set.
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* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
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*
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* @note This function sets the output baud rate in the termios structure pointed to by tio.
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* The speed parameter specifies the baud rate to be set.
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* If the specified speed exceeds the CBAUD mask, indicating an invalid baud rate value,
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* errno is set to EINVAL, and the function returns -1.
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* Otherwise, the function clears the CBAUD bits in the c_cflag member of the termios structure
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* and sets them to the specified speed value. It then returns 0 to indicate success.
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*/
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int cfsetospeed(struct termios *tio, speed_t speed)
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{
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if (speed & ~CBAUD)
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{
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errno = EINVAL;
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return -1;
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}
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tio->c_cflag &= ~CBAUD;
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tio->c_cflag |= speed;
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return 0;
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}
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/**
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* @brief Sets the input baud rate in a termios structure.
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* @param tio Pointer to a struct termios where the input baud rate will be set.
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* @param speed Input baud rate to be set.
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* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
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*
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* @note This function sets the input baud rate in the termios structure pointed to by tio.
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* The speed parameter specifies the input baud rate to be set.
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* If the speed parameter is non-zero, indicating a valid baud rate, the function calls
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* cfsetospeed() to set both the input and output baud rates to the specified value.
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* If speed is zero, indicating that no baud rate needs to be set for input, the function returns 0
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* without making any changes to the termios structure.
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*/
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int cfsetispeed(struct termios *tio, speed_t speed)
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{
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return speed ? cfsetospeed(tio, speed) : 0;
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}
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/**
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* @brief Sends a break signal on a terminal.
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* @param fd File descriptor of the terminal device.
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* @param dur Duration of the break signal (ignored).
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* @return Always returns 0.
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*
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* @note This function is a stub and does not send an actual break signal.
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* Sending a break signal with a nonzero duration is implementation-defined,
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* so this function ignores the duration parameter and always returns 0.
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*/
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int tcsendbreak(int fd, int dur)
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{
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/* nonzero duration is implementation-defined, so ignore it */
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return 0;
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}
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/**
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* @brief Flushes data from a terminal input or output queue.
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* @param fd File descriptor of the terminal device.
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* @param queue Queue to be flushed (TCIFLUSH, TCOFLUSH, or TCIOFLUSH).
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* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
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*
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* @note This function flushes data from the input or output queue of the terminal device specified by the file descriptor fd.
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* The queue parameter specifies which queue to flush:
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* - TCIFLUSH: Flushes data from the input queue.
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* - TCOFLUSH: Flushes data from the output queue.
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* - TCIOFLUSH: Flushes data from both the input and output queues.
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* The ioctl system call is used with the TCFLSH command to perform the flush operation.
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* If the ioctl operation fails, errno is set to indicate the error, and the function returns -1.
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*/
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int tcflush(int fd, int queue)
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{
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return ioctl(fd, TCFLSH, (void*)(rt_ubase_t)queue);
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}
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/**
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* @brief Controls the terminal flow control.
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* @param fd File descriptor of the terminal device.
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* @param action Action to be taken for flow control (TCOOFF, TCOON, TCIOFF, or TCION).
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* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
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*
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* @note This function controls the flow of data on the terminal device specified by the file descriptor fd.
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* The action parameter determines the flow control action to be taken:
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* - TCOOFF: Suspends output transmission.
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* - TCOON: Restarts output transmission.
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* - TCIOFF: Suspends input transmission.
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* - TCION: Restarts input transmission.
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* The ioctl system call is used with the TCXONC command to perform the flow control operation.
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* If the ioctl operation fails, errno is set to indicate the error, and the function returns -1.
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*/
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int tcflow(int fd, int action)
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{
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return ioctl(fd, TCXONC, (void*)(rt_ubase_t)action);
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}
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/**
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* @brief Waits until all output written to the terminal is transmitted.
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* @param fd File descriptor of the terminal device.
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* @return Always returns 0.
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*
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* @note This function is a stub and does not perform any action.
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* In POSIX systems, tcdrain() is used to wait until all output written to the terminal
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* is transmitted, but this function does not provide this functionality and simply returns 0 as a placeholder.
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*/
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int tcdrain(int fd)
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{
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return 0;
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}
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/**
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* @brief Sets the terminal attributes to raw mode.
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* @param t Pointer to a struct termios where the terminal attributes will be set.
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*
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* @note This function sets the terminal attributes pointed to by t to raw mode.
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* Raw mode disables special input and output processing features, making the terminal behave more like a data stream.
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* The following modifications are made to the termios structure:
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* - Input flags (c_iflag) are cleared of various processing flags.
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* - Output flags (c_oflag) are cleared to disable output processing.
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* - Local flags (c_lflag) are cleared to disable canonical mode, echoing, and signal handling.
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* - Control flags (c_cflag) are modified to set character size to 8 bits and disable parity.
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* - The VMIN and VTIME control characters are set to 1 and 0, respectively, for non-blocking read behavior.
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*/
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void cfmakeraw(struct termios *t)
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{
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t->c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IXON);
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t->c_oflag &= ~OPOST;
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t->c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
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t->c_cflag &= ~(CSIZE|PARENB);
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t->c_cflag |= CS8;
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t->c_cc[VMIN] = 1;
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t->c_cc[VTIME] = 0;
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}
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/**
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* @brief Sets the input and output baud rates in a termios structure.
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* @param tio Pointer to a struct termios where the input and output baud rates will be set.
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* @param speed Baud rate to be set for both input and output.
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* @return Upon successful completion, returns 0; otherwise, returns -1 and sets errno to indicate the error.
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*
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* @note This function is a wrapper for the cfsetospeed() function.
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* It sets both the input and output baud rates in the termios structure pointed to by tio to the specified speed.
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* The function returns the result of cfsetospeed(), which sets the baud rate for both input and output.
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*/
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int cfsetspeed(struct termios *tio, speed_t speed)
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{
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return cfsetospeed(tio, speed);
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}
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