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ppdev.c

/*
 * linux/drivers/char/ppdev.c
 *
 * This is the code behind /dev/parport* -- it allows a user-space
 * application to use the parport subsystem.
 *
 * Copyright (C) 1998-2000, 2002 Tim Waugh <tim@cyberelk.net>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * A /dev/parportx device node represents an arbitrary device
 * on port 'x'.  The following operations are possible:
 *
 * open           do nothing, set up default IEEE 1284 protocol to be COMPAT
 * close    release port and unregister device (if necessary)
 * ioctl
 *   EXCL   register device exclusively (may fail)
 *   CLAIM  (register device first time) parport_claim_or_block
 *   RELEASE      parport_release
 *   SETMODE      set the IEEE 1284 protocol to use for read/write
 *   SETPHASE     set the IEEE 1284 phase of a particular mode.  Not to be
 *              confused with ioctl(fd, SETPHASER, &stun). ;-)
 *   DATADIR      data_forward / data_reverse
 *   WDATA  write_data
 *   RDATA  read_data
 *   WCONTROL     write_control
 *   RCONTROL     read_control
 *   FCONTROL     frob_control
 *   RSTATUS      read_status
 *   NEGOT  parport_negotiate
 *   YIELD  parport_yield_blocking
 *   WCTLONIRQ    on interrupt, set control lines
 *   CLRIRQ clear (and return) interrupt count
 *   SETTIME      sets device timeout (struct timeval)
 *   GETTIME      gets device timeout (struct timeval)
 *   GETMODES     gets hardware supported modes (unsigned int)
 *   GETMODE      gets the current IEEE1284 mode
 *   GETPHASE   gets the current IEEE1284 phase
 *   GETFLAGS   gets current (user-visible) flags
 *   SETFLAGS   sets current (user-visible) flags
 * read/write     read or write in current IEEE 1284 protocol
 * select   wait for interrupt (in readfds)
 *
 * Changes:
 * Added SETTIME/GETTIME ioctl, Fred Barnes, 1999.
 *
 * Arnaldo Carvalho de Melo <acme@conectiva.com.br> 2000/08/25
 * - On error, copy_from_user and copy_to_user do not return -EFAULT,
 *   They return the positive number of bytes *not* copied due to address
 *   space errors.
 *
 * Added GETMODES/GETMODE/GETPHASE ioctls, Fred Barnes <frmb2@ukc.ac.uk>, 03/01/2001.
 * Added GETFLAGS/SETFLAGS ioctls, Fred Barnes, 04/2001
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/ioctl.h>
#include <linux/parport.h>
#include <linux/ctype.h>
#include <linux/poll.h>
#include <linux/major.h>
#include <linux/ppdev.h>
#include <asm/uaccess.h>

#define PP_VERSION "ppdev: user-space parallel port driver"
#define CHRDEV "ppdev"

struct pp_struct {
      struct pardevice * pdev;
      wait_queue_head_t irq_wait;
      atomic_t irqc;
      unsigned int flags;
      int irqresponse;
      unsigned char irqctl;
      struct ieee1284_info state;
      struct ieee1284_info saved_state;
      long default_inactivity;
};

/* pp_struct.flags bitfields */
#define PP_CLAIMED    (1<<0)
#define PP_EXCL       (1<<1)

/* Other constants */
#define PP_INTERRUPT_TIMEOUT (10 * HZ) /* 10s */
#define PP_BUFFER_SIZE 1024
#define PARDEVICE_MAX 8

/* ROUND_UP macro from fs/select.c */
#define ROUND_UP(x,y) (((x)+(y)-1)/(y))

static inline void pp_enable_irq (struct pp_struct *pp)
{
      struct parport *port = pp->pdev->port;
      port->ops->enable_irq (port);
}

static ssize_t pp_read (struct file * file, char __user * buf, size_t count,
                  loff_t * ppos)
{
      unsigned int minor = iminor(file->f_path.dentry->d_inode);
      struct pp_struct *pp = file->private_data;
      char * kbuffer;
      ssize_t bytes_read = 0;
      struct parport *pport;
      int mode;

      if (!(pp->flags & PP_CLAIMED)) {
            /* Don't have the port claimed */
            printk (KERN_DEBUG CHRDEV "%x: claim the port first\n",
                  minor);
            return -EINVAL;
      }

      /* Trivial case. */
      if (count == 0)
            return 0;

      kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
      if (!kbuffer) {
            return -ENOMEM;
      }
      pport = pp->pdev->port;
      mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

      parport_set_timeout (pp->pdev,
                       (file->f_flags & O_NONBLOCK) ?
                       PARPORT_INACTIVITY_O_NONBLOCK :
                       pp->default_inactivity);

      while (bytes_read == 0) {
            ssize_t need = min_t(unsigned long, count, PP_BUFFER_SIZE);

            if (mode == IEEE1284_MODE_EPP) {
                  /* various specials for EPP mode */
                  int flags = 0;
                  size_t (*fn)(struct parport *, void *, size_t, int);

                  if (pp->flags & PP_W91284PIC) {
                        flags |= PARPORT_W91284PIC;
                  }
                  if (pp->flags & PP_FASTREAD) {
                        flags |= PARPORT_EPP_FAST;
                  }
                  if (pport->ieee1284.mode & IEEE1284_ADDR) {
                        fn = pport->ops->epp_read_addr;
                  } else {
                        fn = pport->ops->epp_read_data;
                  }
                  bytes_read = (*fn)(pport, kbuffer, need, flags);
            } else {
                  bytes_read = parport_read (pport, kbuffer, need);
            }

            if (bytes_read != 0)
                  break;

            if (file->f_flags & O_NONBLOCK) {
                  bytes_read = -EAGAIN;
                  break;
            }

            if (signal_pending (current)) {
                  bytes_read = -ERESTARTSYS;
                  break;
            }

            cond_resched();
      }

      parport_set_timeout (pp->pdev, pp->default_inactivity);

      if (bytes_read > 0 && copy_to_user (buf, kbuffer, bytes_read))
            bytes_read = -EFAULT;

      kfree (kbuffer);
      pp_enable_irq (pp);
      return bytes_read;
}

static ssize_t pp_write (struct file * file, const char __user * buf,
                   size_t count, loff_t * ppos)
{
      unsigned int minor = iminor(file->f_path.dentry->d_inode);
      struct pp_struct *pp = file->private_data;
      char * kbuffer;
      ssize_t bytes_written = 0;
      ssize_t wrote;
      int mode;
      struct parport *pport;

      if (!(pp->flags & PP_CLAIMED)) {
            /* Don't have the port claimed */
            printk (KERN_DEBUG CHRDEV "%x: claim the port first\n",
                  minor);
            return -EINVAL;
      }

      kbuffer = kmalloc(min_t(size_t, count, PP_BUFFER_SIZE), GFP_KERNEL);
      if (!kbuffer) {
            return -ENOMEM;
      }
      pport = pp->pdev->port;
      mode = pport->ieee1284.mode & ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

      parport_set_timeout (pp->pdev,
                       (file->f_flags & O_NONBLOCK) ?
                       PARPORT_INACTIVITY_O_NONBLOCK :
                       pp->default_inactivity);

      while (bytes_written < count) {
            ssize_t n = min_t(unsigned long, count - bytes_written, PP_BUFFER_SIZE);

            if (copy_from_user (kbuffer, buf + bytes_written, n)) {
                  bytes_written = -EFAULT;
                  break;
            }

            if ((pp->flags & PP_FASTWRITE) && (mode == IEEE1284_MODE_EPP)) {
                  /* do a fast EPP write */
                  if (pport->ieee1284.mode & IEEE1284_ADDR) {
                        wrote = pport->ops->epp_write_addr (pport,
                              kbuffer, n, PARPORT_EPP_FAST);
                  } else {
                        wrote = pport->ops->epp_write_data (pport,
                              kbuffer, n, PARPORT_EPP_FAST);
                  }
            } else {
                  wrote = parport_write (pp->pdev->port, kbuffer, n);
            }

            if (wrote <= 0) {
                  if (!bytes_written) {
                        bytes_written = wrote;
                  }
                  break;
            }

            bytes_written += wrote;

            if (file->f_flags & O_NONBLOCK) {
                  if (!bytes_written)
                        bytes_written = -EAGAIN;
                  break;
            }

            if (signal_pending (current)) {
                  if (!bytes_written) {
                        bytes_written = -EINTR;
                  }
                  break;
            }

            cond_resched();
      }

      parport_set_timeout (pp->pdev, pp->default_inactivity);

      kfree (kbuffer);
      pp_enable_irq (pp);
      return bytes_written;
}

static void pp_irq (void *private)
{
      struct pp_struct *pp = private;

      if (pp->irqresponse) {
            parport_write_control (pp->pdev->port, pp->irqctl);
            pp->irqresponse = 0;
      }

      atomic_inc (&pp->irqc);
      wake_up_interruptible (&pp->irq_wait);
}

static int register_device (int minor, struct pp_struct *pp)
{
      struct parport *port;
      struct pardevice * pdev = NULL;
      char *name;
      int fl;

      name = kmalloc (strlen (CHRDEV) + 3, GFP_KERNEL);
      if (name == NULL)
            return -ENOMEM;

      sprintf (name, CHRDEV "%x", minor);

      port = parport_find_number (minor);
      if (!port) {
            printk (KERN_WARNING "%s: no associated port!\n", name);
            kfree (name);
            return -ENXIO;
      }

      fl = (pp->flags & PP_EXCL) ? PARPORT_FLAG_EXCL : 0;
      pdev = parport_register_device (port, name, NULL,
                              NULL, pp_irq, fl, pp);
      parport_put_port (port);

      if (!pdev) {
            printk (KERN_WARNING "%s: failed to register device!\n", name);
            kfree (name);
            return -ENXIO;
      }

      pp->pdev = pdev;
      printk (KERN_DEBUG "%s: registered pardevice\n", name);
      return 0;
}

static enum ieee1284_phase init_phase (int mode)
{
      switch (mode & ~(IEEE1284_DEVICEID
                   | IEEE1284_ADDR)) {
      case IEEE1284_MODE_NIBBLE:
      case IEEE1284_MODE_BYTE:
            return IEEE1284_PH_REV_IDLE;
      }
      return IEEE1284_PH_FWD_IDLE;
}

static int pp_ioctl(struct inode *inode, struct file *file,
                unsigned int cmd, unsigned long arg)
{
      unsigned int minor = iminor(inode);
      struct pp_struct *pp = file->private_data;
      struct parport * port;
      void __user *argp = (void __user *)arg;

      /* First handle the cases that don't take arguments. */
      switch (cmd) {
      case PPCLAIM:
          {
            struct ieee1284_info *info;
            int ret;

            if (pp->flags & PP_CLAIMED) {
                  printk (KERN_DEBUG CHRDEV
                        "%x: you've already got it!\n", minor);
                  return -EINVAL;
            }

            /* Deferred device registration. */
            if (!pp->pdev) {
                  int err = register_device (minor, pp);
                  if (err) {
                        return err;
                  }
            }

            ret = parport_claim_or_block (pp->pdev);
            if (ret < 0)
                  return ret;

            pp->flags |= PP_CLAIMED;

            /* For interrupt-reporting to work, we need to be
             * informed of each interrupt. */
            pp_enable_irq (pp);

            /* We may need to fix up the state machine. */
            info = &pp->pdev->port->ieee1284;
            pp->saved_state.mode = info->mode;
            pp->saved_state.phase = info->phase;
            info->mode = pp->state.mode;
            info->phase = pp->state.phase;
            pp->default_inactivity = parport_set_timeout (pp->pdev, 0);
            parport_set_timeout (pp->pdev, pp->default_inactivity);

            return 0;
          }
      case PPEXCL:
            if (pp->pdev) {
                  printk (KERN_DEBUG CHRDEV "%x: too late for PPEXCL; "
                        "already registered\n", minor);
                  if (pp->flags & PP_EXCL)
                        /* But it's not really an error. */
                        return 0;
                  /* There's no chance of making the driver happy. */
                  return -EINVAL;
            }

            /* Just remember to register the device exclusively
             * when we finally do the registration. */
            pp->flags |= PP_EXCL;
            return 0;
      case PPSETMODE:
          {
            int mode;
            if (copy_from_user (&mode, argp, sizeof (mode)))
                  return -EFAULT;
            /* FIXME: validate mode */
            pp->state.mode = mode;
            pp->state.phase = init_phase (mode);

            if (pp->flags & PP_CLAIMED) {
                  pp->pdev->port->ieee1284.mode = mode;
                  pp->pdev->port->ieee1284.phase = pp->state.phase;
            }

            return 0;
          }
      case PPGETMODE:
          {
            int mode;

            if (pp->flags & PP_CLAIMED) {
                  mode = pp->pdev->port->ieee1284.mode;
            } else {
                  mode = pp->state.mode;
            }
            if (copy_to_user (argp, &mode, sizeof (mode))) {
                  return -EFAULT;
            }
            return 0;
          }
      case PPSETPHASE:
          {
            int phase;
            if (copy_from_user (&phase, argp, sizeof (phase))) {
                  return -EFAULT;
            }
            /* FIXME: validate phase */
            pp->state.phase = phase;

            if (pp->flags & PP_CLAIMED) {
                  pp->pdev->port->ieee1284.phase = phase;
            }

            return 0;
          }
      case PPGETPHASE:
          {
            int phase;

            if (pp->flags & PP_CLAIMED) {
                  phase = pp->pdev->port->ieee1284.phase;
            } else {
                  phase = pp->state.phase;
            }
            if (copy_to_user (argp, &phase, sizeof (phase))) {
                  return -EFAULT;
            }
            return 0;
          }
      case PPGETMODES:
          {
            unsigned int modes;

            port = parport_find_number (minor);
            if (!port)
                  return -ENODEV;

            modes = port->modes;
            if (copy_to_user (argp, &modes, sizeof (modes))) {
                  return -EFAULT;
            }
            return 0;
          }
      case PPSETFLAGS:
          {
            int uflags;

            if (copy_from_user (&uflags, argp, sizeof (uflags))) {
                  return -EFAULT;
            }
            pp->flags &= ~PP_FLAGMASK;
            pp->flags |= (uflags & PP_FLAGMASK);
            return 0;
          }
      case PPGETFLAGS:
          {
            int uflags;

            uflags = pp->flags & PP_FLAGMASK;
            if (copy_to_user (argp, &uflags, sizeof (uflags))) {
                  return -EFAULT;
            }
            return 0;
          }
      }     /* end switch() */

      /* Everything else requires the port to be claimed, so check
       * that now. */
      if ((pp->flags & PP_CLAIMED) == 0) {
            printk (KERN_DEBUG CHRDEV "%x: claim the port first\n",
                  minor);
            return -EINVAL;
      }

      port = pp->pdev->port;
      switch (cmd) {
            struct ieee1284_info *info;
            unsigned char reg;
            unsigned char mask;
            int mode;
            int ret;
            struct timeval par_timeout;
            long to_jiffies;

      case PPRSTATUS:
            reg = parport_read_status (port);
            if (copy_to_user (argp, &reg, sizeof (reg)))
                  return -EFAULT;
            return 0;
      case PPRDATA:
            reg = parport_read_data (port);
            if (copy_to_user (argp, &reg, sizeof (reg)))
                  return -EFAULT;
            return 0;
      case PPRCONTROL:
            reg = parport_read_control (port);
            if (copy_to_user (argp, &reg, sizeof (reg)))
                  return -EFAULT;
            return 0;
      case PPYIELD:
            parport_yield_blocking (pp->pdev);
            return 0;

      case PPRELEASE:
            /* Save the state machine's state. */
            info = &pp->pdev->port->ieee1284;
            pp->state.mode = info->mode;
            pp->state.phase = info->phase;
            info->mode = pp->saved_state.mode;
            info->phase = pp->saved_state.phase;
            parport_release (pp->pdev);
            pp->flags &= ~PP_CLAIMED;
            return 0;

      case PPWCONTROL:
            if (copy_from_user (&reg, argp, sizeof (reg)))
                  return -EFAULT;
            parport_write_control (port, reg);
            return 0;

      case PPWDATA:
            if (copy_from_user (&reg, argp, sizeof (reg)))
                  return -EFAULT;
            parport_write_data (port, reg);
            return 0;

      case PPFCONTROL:
            if (copy_from_user (&mask, argp,
                            sizeof (mask)))
                  return -EFAULT;
            if (copy_from_user (&reg, 1 + (unsigned char __user *) arg,
                            sizeof (reg)))
                  return -EFAULT;
            parport_frob_control (port, mask, reg);
            return 0;

      case PPDATADIR:
            if (copy_from_user (&mode, argp, sizeof (mode)))
                  return -EFAULT;
            if (mode)
                  port->ops->data_reverse (port);
            else
                  port->ops->data_forward (port);
            return 0;

      case PPNEGOT:
            if (copy_from_user (&mode, argp, sizeof (mode)))
                  return -EFAULT;
            switch ((ret = parport_negotiate (port, mode))) {
            case 0: break;
            case -1: /* handshake failed, peripheral not IEEE 1284 */
                  ret = -EIO;
                  break;
            case 1:  /* handshake succeeded, peripheral rejected mode */
                  ret = -ENXIO;
                  break;
            }
            pp_enable_irq (pp);
            return ret;

      case PPWCTLONIRQ:
            if (copy_from_user (&reg, argp, sizeof (reg)))
                  return -EFAULT;

            /* Remember what to set the control lines to, for next
             * time we get an interrupt. */
            pp->irqctl = reg;
            pp->irqresponse = 1;
            return 0;

      case PPCLRIRQ:
            ret = atomic_read (&pp->irqc);
            if (copy_to_user (argp, &ret, sizeof (ret)))
                  return -EFAULT;
            atomic_sub (ret, &pp->irqc);
            return 0;

      case PPSETTIME:
            if (copy_from_user (&par_timeout, argp, sizeof(struct timeval))) {
                  return -EFAULT;
            }
            /* Convert to jiffies, place in pp->pdev->timeout */
            if ((par_timeout.tv_sec < 0) || (par_timeout.tv_usec < 0)) {
                  return -EINVAL;
            }
            to_jiffies = ROUND_UP(par_timeout.tv_usec, 1000000/HZ);
            to_jiffies += par_timeout.tv_sec * (long)HZ;
            if (to_jiffies <= 0) {
                  return -EINVAL;
            }
            pp->pdev->timeout = to_jiffies;
            return 0;

      case PPGETTIME:
            to_jiffies = pp->pdev->timeout;
            par_timeout.tv_sec = to_jiffies / HZ;
            par_timeout.tv_usec = (to_jiffies % (long)HZ) * (1000000/HZ);
            if (copy_to_user (argp, &par_timeout, sizeof(struct timeval)))
                  return -EFAULT;
            return 0;

      default:
            printk (KERN_DEBUG CHRDEV "%x: What? (cmd=0x%x)\n", minor,
                  cmd);
            return -EINVAL;
      }

      /* Keep the compiler happy */
      return 0;
}

static int pp_open (struct inode * inode, struct file * file)
{
      unsigned int minor = iminor(inode);
      struct pp_struct *pp;

      if (minor >= PARPORT_MAX)
            return -ENXIO;

      pp = kmalloc (sizeof (struct pp_struct), GFP_KERNEL);
      if (!pp)
            return -ENOMEM;

      pp->state.mode = IEEE1284_MODE_COMPAT;
      pp->state.phase = init_phase (pp->state.mode);
      pp->flags = 0;
      pp->irqresponse = 0;
      atomic_set (&pp->irqc, 0);
      init_waitqueue_head (&pp->irq_wait);

      /* Defer the actual device registration until the first claim.
       * That way, we know whether or not the driver wants to have
       * exclusive access to the port (PPEXCL).
       */
      pp->pdev = NULL;
      file->private_data = pp;

      return 0;
}

static int pp_release (struct inode * inode, struct file * file)
{
      unsigned int minor = iminor(inode);
      struct pp_struct *pp = file->private_data;
      int compat_negot;

      compat_negot = 0;
      if (!(pp->flags & PP_CLAIMED) && pp->pdev &&
          (pp->state.mode != IEEE1284_MODE_COMPAT)) {
            struct ieee1284_info *info;

            /* parport released, but not in compatibility mode */
            parport_claim_or_block (pp->pdev);
            pp->flags |= PP_CLAIMED;
            info = &pp->pdev->port->ieee1284;
            pp->saved_state.mode = info->mode;
            pp->saved_state.phase = info->phase;
            info->mode = pp->state.mode;
            info->phase = pp->state.phase;
            compat_negot = 1;
      } else if ((pp->flags & PP_CLAIMED) && pp->pdev &&
          (pp->pdev->port->ieee1284.mode != IEEE1284_MODE_COMPAT)) {
            compat_negot = 2;
      }
      if (compat_negot) {
            parport_negotiate (pp->pdev->port, IEEE1284_MODE_COMPAT);
            printk (KERN_DEBUG CHRDEV
                  "%x: negotiated back to compatibility mode because "
                  "user-space forgot\n", minor);
      }

      if (pp->flags & PP_CLAIMED) {
            struct ieee1284_info *info;

            info = &pp->pdev->port->ieee1284;
            pp->state.mode = info->mode;
            pp->state.phase = info->phase;
            info->mode = pp->saved_state.mode;
            info->phase = pp->saved_state.phase;
            parport_release (pp->pdev);
            if (compat_negot != 1) {
                  printk (KERN_DEBUG CHRDEV "%x: released pardevice "
                        "because user-space forgot\n", minor);
            }
      }

      if (pp->pdev) {
            const char *name = pp->pdev->name;
            parport_unregister_device (pp->pdev);
            kfree (name);
            pp->pdev = NULL;
            printk (KERN_DEBUG CHRDEV "%x: unregistered pardevice\n",
                  minor);
      }

      kfree (pp);

      return 0;
}

/* No kernel lock held - fine */
static unsigned int pp_poll (struct file * file, poll_table * wait)
{
      struct pp_struct *pp = file->private_data;
      unsigned int mask = 0;

      poll_wait (file, &pp->irq_wait, wait);
      if (atomic_read (&pp->irqc))
            mask |= POLLIN | POLLRDNORM;

      return mask;
}

static struct class *ppdev_class;

static const struct file_operations pp_fops = {
      .owner            = THIS_MODULE,
      .llseek           = no_llseek,
      .read       = pp_read,
      .write            = pp_write,
      .poll       = pp_poll,
      .ioctl            = pp_ioctl,
      .open       = pp_open,
      .release    = pp_release,
};

static void pp_attach(struct parport *port)
{
      device_create(ppdev_class, port->dev, MKDEV(PP_MAJOR, port->number),
                  "parport%d", port->number);
}

static void pp_detach(struct parport *port)
{
      device_destroy(ppdev_class, MKDEV(PP_MAJOR, port->number));
}

static struct parport_driver pp_driver = {
      .name       = CHRDEV,
      .attach           = pp_attach,
      .detach           = pp_detach,
};

static int __init ppdev_init (void)
{
      int err = 0;

      if (register_chrdev (PP_MAJOR, CHRDEV, &pp_fops)) {
            printk (KERN_WARNING CHRDEV ": unable to get major %d\n",
                  PP_MAJOR);
            return -EIO;
      }
      ppdev_class = class_create(THIS_MODULE, CHRDEV);
      if (IS_ERR(ppdev_class)) {
            err = PTR_ERR(ppdev_class);
            goto out_chrdev;
      }
      if (parport_register_driver(&pp_driver)) {
            printk (KERN_WARNING CHRDEV ": unable to register with parport\n");
            goto out_class;
      }

      printk (KERN_INFO PP_VERSION "\n");
      goto out;

out_class:
      class_destroy(ppdev_class);
out_chrdev:
      unregister_chrdev(PP_MAJOR, CHRDEV);
out:
      return err;
}

static void __exit ppdev_cleanup (void)
{
      /* Clean up all parport stuff */
      parport_unregister_driver(&pp_driver);
      class_destroy(ppdev_class);
      unregister_chrdev (PP_MAJOR, CHRDEV);
}

module_init(ppdev_init);
module_exit(ppdev_cleanup);

MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(PP_MAJOR);

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