drivers/ioexpander/gpio.c: support reading and writing gpio pins using cat and echo.
This commit is contained in:
Valmantas Paliksa
Gregory Nutt
parent
f88597203d
commit
90ee863abe
@ -1,7 +1,7 @@
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/****************************************************************************
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* drivers/ioexpander/gpio.c
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*
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* Copyright (C) 2016, 2018 Gregory Nutt. All rights reserved.
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* Copyright (C) 2016, 2018-2019 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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@ -45,6 +45,7 @@
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#include <signal.h>
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#include <assert.h>
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#include <errno.h>
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#include <unistd.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/ioexpander/gpio.h>
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@ -62,6 +63,7 @@ static ssize_t gpio_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t gpio_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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static off_t gpio_seek(FAR struct file *filep, off_t offset, int whence);
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static int gpio_ioctl(FAR struct file *filep, int cmd,
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unsigned long arg);
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@ -75,7 +77,7 @@ static const struct file_operations g_gpio_drvrops =
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gpio_close, /* close */
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gpio_read, /* read */
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gpio_write, /* write */
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NULL, /* seek */
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gpio_seek, /* seek */
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gpio_ioctl /* ioctl */
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#ifndef CONFIG_DISABLE_POLL
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, NULL /* poll */
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@ -129,6 +131,7 @@ static int gpio_handler(FAR struct gpio_dev_s *dev, uint8_t pin)
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static int gpio_open(FAR struct file *filep)
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{
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filep->f_pos = 0;
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return OK;
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}
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@ -156,7 +159,47 @@ static int gpio_close(FAR struct file *filep)
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static ssize_t gpio_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen)
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{
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return 0;
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FAR struct inode *inode;
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FAR struct gpio_dev_s *dev;
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int ret;
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DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
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inode = filep->f_inode;
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DEBUGASSERT(inode->i_private != NULL);
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dev = inode->i_private;
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DEBUGASSERT(buffer != NULL);
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if (buflen == 0)
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{
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return 0; /* Zero will be interpreted as the End-of-File. */
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}
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/* Check for End-of-File.
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*
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* REVISIT: Returning End-of-File after one byte has been written permits
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* you to cat or echo the GPIO. This, however, is an un-natural use of a
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* file position since there is no file position associated with a GPIO.
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* It also makes the read() method difficult to use programmatically.
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*/
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if (filep->f_pos > 0)
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{
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return 0;
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}
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/* Read the GPIO value */
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ret = dev->gp_ops->go_read(dev, (FAR uint8_t *)&buffer[0]);
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if (ret < 0)
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{
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return ret;
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}
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/* Convert the GPIO value to ASCII and increment the file position */
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buffer[0] += '0';
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filep->f_pos = 1;
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return 1;
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}
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/****************************************************************************
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@ -165,12 +208,99 @@ static ssize_t gpio_read(FAR struct file *filep, FAR char *buffer,
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* Description:
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* Standard character driver write method.
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*
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* REVISIT: The read() method obeys the semantics of a file position and
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* requires re-opening the driver or seeking to address 0. The write()
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* method does not. This is an inconsistency.
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*
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****************************************************************************/
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static ssize_t gpio_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen)
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{
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return (ssize_t)buflen;
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FAR struct inode *inode;
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FAR struct gpio_dev_s *dev;
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int ret;
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bool val;
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DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
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inode = filep->f_inode;
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DEBUGASSERT(inode->i_private != NULL);
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dev = inode->i_private;
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DEBUGASSERT(buffer != NULL);
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/* Check if this pin is write-able */
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if (dev->gp_pintype != GPIO_OUTPUT_PIN)
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{
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return -EACCES;
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}
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/* Verfy that a buffer containing data was provided */
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DEBUGASSERT(buffer != NULL);
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if (buflen != 0)
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{
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/* Only values '0' and '1' can be written */
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if (buffer[0] == '0')
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{
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val = 0;
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}
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else if (buffer[0] == '1')
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{
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val = 1;
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}
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/* Write the GPIO value */
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ret = dev->gp_ops->go_write(dev, val);
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if (ret < 0)
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{
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return ret;
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}
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/* One byte written */
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return 1;
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}
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return 0;
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}
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/****************************************************************************
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* Name: gpio_seek
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*
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* Description:
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* Reset read flag on seek to 0
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*
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* REVISIT: Seeking address zero is required to return addition GPIO
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* values from read(). This, however, is an un-natural use of a file
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* position since there is no file position associated with a GPIO. It
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* also makes the read() method difficult to use programmatically.
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*
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****************************************************************************/
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static off_t gpio_seek(FAR struct file *filep, off_t offset, int whence)
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{
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/* Only SEEK_SET is supported, return ENOSYS for other valid options */
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if (whence == SEEK_CUR || whence == SEEK_END)
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{
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return -ENOSYS;
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}
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/* Only Offset zero makes sense, POSIX permits setting the file position
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* beyond the end of the file, but that makes little sense here.
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*/
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if (whence == SEEK_SET && offset == 0)
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{
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filep->f_pos = 0;
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return 0;
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}
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return -EINVAL;
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}
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/****************************************************************************
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@ -189,7 +319,7 @@ static int gpio_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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pid_t pid;
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int ret;
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int i;
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int j;
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int j = 0;
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DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
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inode = filep->f_inode;
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@ -238,7 +368,8 @@ static int gpio_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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case GPIOC_PINTYPE:
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{
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FAR enum gpio_pintype_e *ptr = (FAR enum gpio_pintype_e *)((uintptr_t)arg);
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FAR enum gpio_pintype_e *ptr =
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(FAR enum gpio_pintype_e *)((uintptr_t)arg);
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DEBUGASSERT(ptr != NULL);
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*ptr = dev->gp_pintype;
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@ -405,7 +536,8 @@ int gpio_pin_register(FAR struct gpio_dev_s *dev, int minor)
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char devname[16];
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int ret;
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DEBUGASSERT(dev != NULL && dev->gp_ops != NULL && (unsigned int)minor < 100);
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DEBUGASSERT(dev != NULL && dev->gp_ops != NULL &&
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(unsigned int)minor < 100);
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switch (dev->gp_pintype)
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{
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@ -421,7 +553,6 @@ int gpio_pin_register(FAR struct gpio_dev_s *dev, int minor)
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DEBUGASSERT(dev->gp_ops->go_read != NULL &&
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dev->gp_ops->go_write != NULL);
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fmt = "/dev/gpout%u";
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}
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break;
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