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- /************************************************************************************
- * drivers/serial/serial_io.c
- *
- * Copyright (C) 2007-2009, 2011, 2015, 2018 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 <nuttx/config.h>
- #include <sys/types.h>
- #include <stdint.h>
- #include <semaphore.h>
- #include <debug.h>
- #include <nuttx/serial/serial.h>
- /************************************************************************************
- * Public Functions
- ************************************************************************************/
- /************************************************************************************
- * Name: uart_xmitchars
- *
- * Description:
- * This function is called from the UART interrupt handler when an interrupt
- * is received indicating that there is more space in the transmit FIFO. This
- * function will send characters from the tail of the xmit buffer while the driver
- * write() logic adds data to the head of the xmit buffer.
- *
- ************************************************************************************/
- void uart_xmitchars(FAR uart_dev_t *dev)
- {
- uint16_t nbytes = 0;
- /* Send while we still have data in the TX buffer & room in the fifo */
- while (dev->xmit.head != dev->xmit.tail && uart_txready(dev))
- {
- /* Send the next byte */
- uart_send(dev, dev->xmit.buffer[dev->xmit.tail]);
- nbytes++;
- /* Increment the tail index */
- if (++(dev->xmit.tail) >= dev->xmit.size)
- {
- dev->xmit.tail = 0;
- }
- }
- /* When all of the characters have been sent from the buffer disable the TX
- * interrupt.
- *
- * Potential bug? If nbytes == 0 && (dev->xmit.head == dev->xmit.tail) &&
- * dev->xmitwaiting == true, then disabling the TX interrupt will leave
- * the uart_write() logic waiting to TX to complete with no TX interrupts.
- * Can that happen?
- */
- if (dev->xmit.head == dev->xmit.tail)
- {
- uart_disabletxint(dev);
- }
- /* If any bytes were removed from the buffer, inform any waiters there there is
- * space available.
- */
- if (nbytes)
- {
- uart_datasent(dev);
- }
- }
- /************************************************************************************
- * Name: uart_receivechars
- *
- * Description:
- * This function is called from the UART interrupt handler when an interrupt
- * is received indicating that are bytes available in the receive fifo. This
- * function will add chars to head of receive buffer. Driver read() logic will
- * take characters from the tail of the buffer.
- *
- ************************************************************************************/
- void uart_recvchars(FAR uart_dev_t *dev)
- {
- FAR struct uart_buffer_s *rxbuf = &dev->recv;
- #ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
- unsigned int watermark;
- #endif
- unsigned int status;
- int nexthead = rxbuf->head + 1;
- #if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
- int signo = 0;
- #endif
- uint16_t nbytes = 0;
- if (nexthead >= rxbuf->size)
- {
- nexthead = 0;
- }
- #ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
- /* Pre-calculate the watermark level that we will need to test against. */
- watermark = (CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK * rxbuf->size) / 100;
- #endif
- /* Loop putting characters into the receive buffer until there are no further
- * characters to available.
- */
- while (uart_rxavailable(dev))
- {
- bool is_full = (nexthead == rxbuf->tail);
- char ch;
- #ifdef CONFIG_SERIAL_IFLOWCONTROL
- #ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
- unsigned int nbuffered;
- /* How many bytes are buffered */
- if (rxbuf->head >= rxbuf->tail)
- {
- nbuffered = rxbuf->head - rxbuf->tail;
- }
- else
- {
- nbuffered = rxbuf->size - rxbuf->tail + rxbuf->head;
- }
- /* Is the level now above the watermark level that we need to report? */
- if (nbuffered >= watermark)
- {
- /* Let the lower level driver know that the watermark level has been
- * crossed. It will probably activate RX flow control.
- */
- if (uart_rxflowcontrol(dev, nbuffered, true))
- {
- /* Low-level driver activated RX flow control, exit loop now. */
- break;
- }
- }
- #else
- /* Check if RX buffer is full and allow serial low-level driver to pause
- * processing. This allows proper utilization of hardware flow control.
- */
- if (is_full)
- {
- if (uart_rxflowcontrol(dev, rxbuf->size, true))
- {
- /* Low-level driver activated RX flow control, exit loop now. */
- break;
- }
- }
- #endif
- #endif
- /* Get this next character from the hardware */
- ch = uart_receive(dev, &status);
- #ifdef CONFIG_TTY_SIGINT
- /* Is this the special character that will generate the SIGINT signal? */
- if (dev->pid >= 0 && ch == CONFIG_TTY_SIGINT_CHAR)
- {
- /* Yes.. note that the kill is needed and do not put the character
- * into the Rx buffer. It should not be read as normal data.
- */
- signo = SIGINT;
- }
- else
- #endif
- #ifdef CONFIG_TTY_SIGSTP
- /* Is this the special character that will generate the SIGSTP signal? */
- if (dev->pid >= 0 && ch == CONFIG_TTY_SIGSTP_CHAR)
- {
- #ifdef CONFIG_TTY_SIGINT
- /* Give precedence to SIGINT */
- if (signo == 0)
- #endif
- {
- /* Note that the kill is needed and do not put the character
- * into the Rx buffer. It should not be read as normal data.
- */
- signo = SIGSTP;
- }
- }
- else
- #endif
- /* If the RX buffer becomes full, then the serial data is discarded. This is
- * necessary because on most serial hardware, you must read the data in order
- * to clear the RX interrupt. An option on some hardware might be to simply
- * disable RX interrupts until the RX buffer becomes non-FULL. However, that
- * would probably just cause the overrun to occur in hardware (unless it has
- * some large internal buffering).
- */
- if (!is_full)
- {
- /* Add the character to the buffer */
- rxbuf->buffer[rxbuf->head] = ch;
- nbytes++;
- /* Increment the head index */
- rxbuf->head = nexthead;
- if (++nexthead >= rxbuf->size)
- {
- nexthead = 0;
- }
- }
- }
- /* If any bytes were added to the buffer, inform any waiters there is new
- * incoming data available.
- */
- if (nbytes)
- {
- uart_datareceived(dev);
- }
- #if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
- /* Send the signal if necessary */
- if (signo != 0)
- {
- kill(dev->pid, signo);
- uart_reset_sem(dev);
- }
- #endif
- }
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