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/******************************************************************************

*                                                                             *

* License Agreement                                                           *

*                                                                             *

* Copyright (c) 2004 Altera Corporation, San Jose, California, USA.           *

* All rights reserved.                                                        *

*                                                                             *

* Permission is hereby granted, free of charge, to any person obtaining a     *

* copy of this software and associated documentation files (the "Software"),  *

* to deal in the Software without restriction, including without limitation   *

* the rights to use, copy, modify, merge, publish, distribute, sublicense,    *

* and/or sell copies of the Software, and to permit persons to whom the       *

* Software is furnished to do so, subject to the following conditions:        *

*                                                                             *

* The above copyright notice and this permission notice shall be included in  *

* all copies or substantial portions of the Software.                         *

*                                                                             *

* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  *

* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    *

* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *

* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      *

* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     *

* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         *

* DEALINGS IN THE SOFTWARE.                                                   *

*                                                                             *

* This agreement shall be governed in all respects by the laws of the State   *

* of California and by the laws of the United States of America.              *

*                                                                             *

* Altera does not recommend, suggest or require that this reference design    *

* file be used in conjunction or combination with any other product.          *

******************************************************************************/

#include <stddef.h>

#include <stdio.h>

#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include "sys/alt_dev.h"

#include "priv/alt_file.h"

#include "alt_types.h"

#include "system.h"

/*

 * This file contains the data constructs used to control access to device and

 * filesytems.

 */

/*

 * "alt_fs_list" is the head of a linked list of registered filesystems. It is

 * initialised as an empty list. New entries can be added using the

 * alt_fs_reg() function.

 */

ALT_LLIST_HEAD(alt_fs_list);

/*

 * "alt_dev_list" is the head of a linked list of registered devices. It is

 * configured at startup to include a single device, "alt_dev_null". This

 * device is discussed below.

 */

extern alt_dev alt_dev_null; /* forward declaration */

alt_llist alt_dev_list = {&alt_dev_null.llist, &alt_dev_null.llist};

/*

 * alt_dev_null_write() is the implementation of the write() function used

 * by the alt_dev_null device. It simple discards all data passed to it, and

 * indicates that the data has been successfully transmitted.

 */

static int alt_dev_null_write (alt_fd* fd, const char* ptr, int len)

{

  return len;

}

/*

 * "alt_dev_null" is used to allow output to be redirected to nowhere. It is

 * the only device registered before the call to alt_sys_init(). At startup

 * stin, stdout & stderr are all directed towards this device so that library

 * calls like printf() will be safe but inefectual.

 */

alt_dev alt_dev_null = {

   {

     &alt_dev_list,

     &alt_dev_list

   },

   "/dev/null",

   NULL,               /* open */

   NULL,               /* close */

   NULL,               /* write */

   alt_dev_null_write, /* write */

   NULL,               /* lseek */

   NULL,               /* fstat */

   NULL                /* ioctl */

 };

/*

 * "alt_fd_list_lock" is a semaphore used to control access to the file

 * descriptor list. This is used to ensure that access to the list is thread

 * safe.

 */

ALT_SEM(alt_fd_list_lock)

/*

 * "alt_max_fd" is used to make access to the file descriptor list more

 * efficent. It is set to be the value of the highest allocated file

 * descriptor. This saves having to search the entire pool of unallocated

 * file descriptors when looking for a match.

 */

alt_32 alt_max_fd = -1;

/*

 * "alt_fd_list" is the file descriptor pool. The first three entries in the

 * array are configured as standard in, standard out, and standard error. These

 * are all initialised so that accesses are directed to the alt_dev_null

 * device. The remaining file descriptors are initialised as unallocated.

 *

 * The maximum number of file descriptors within the system is specified by the

 * user defined macro "ALT_MAX_FD". This is defined in "system.h", which is

 * auto-genereated using the projects PTF and STF files.

 */

alt_fd alt_fd_list[ALT_MAX_FD] =

  {

    {

      &alt_dev_null, /* standard in */

      0,

    },

    {

      &alt_dev_null, /* standard out */

      0,

    },

    {

      &alt_dev_null, /* standard error */

      0,

    }

    /* all other elements are set to zero */

  };