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1 8 alfik
/******************************************************************************
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*                                                                             *
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* License Agreement                                                           *
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*                                                                             *
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* Copyright (c) 2004 Altera Corporation, San Jose, California, USA.           *
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* All rights reserved.                                                        *
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*                                                                             *
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* Permission is hereby granted, free of charge, to any person obtaining a     *
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* copy of this software and associated documentation files (the "Software"),  *
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* to deal in the Software without restriction, including without limitation   *
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,    *
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* and/or sell copies of the Software, and to permit persons to whom the       *
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* Software is furnished to do so, subject to the following conditions:        *
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*                                                                             *
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* The above copyright notice and this permission notice shall be included in  *
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* all copies or substantial portions of the Software.                         *
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*                                                                             *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  *
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    *
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      *
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     *
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         *
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* DEALINGS IN THE SOFTWARE.                                                   *
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*                                                                             *
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* This agreement shall be governed in all respects by the laws of the State   *
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* of California and by the laws of the United States of America.              *
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*                                                                             *
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* Altera does not recommend, suggest or require that this reference design    *
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* file be used in conjunction or combination with any other product.          *
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******************************************************************************/
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#include <stddef.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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#include "sys/alt_dev.h"
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#include "priv/alt_file.h"
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#include "alt_types.h"
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#include "system.h"
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/*
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 * This file contains the data constructs used to control access to device and
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 * filesytems.
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 */
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/*
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 * "alt_fs_list" is the head of a linked list of registered filesystems. It is
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 * initialised as an empty list. New entries can be added using the
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 * alt_fs_reg() function.
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 */
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ALT_LLIST_HEAD(alt_fs_list);
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/*
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 * "alt_dev_list" is the head of a linked list of registered devices. It is
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 * configured at startup to include a single device, "alt_dev_null". This
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 * device is discussed below.
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 */
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extern alt_dev alt_dev_null; /* forward declaration */
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alt_llist alt_dev_list = {&alt_dev_null.llist, &alt_dev_null.llist};
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/*
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 * alt_dev_null_write() is the implementation of the write() function used
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 * by the alt_dev_null device. It simple discards all data passed to it, and
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 * indicates that the data has been successfully transmitted.
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 */
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static int alt_dev_null_write (alt_fd* fd, const char* ptr, int len)
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{
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  return len;
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}
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/*
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 * "alt_dev_null" is used to allow output to be redirected to nowhere. It is
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 * the only device registered before the call to alt_sys_init(). At startup
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 * stin, stdout & stderr are all directed towards this device so that library
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 * calls like printf() will be safe but inefectual.
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 */
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alt_dev alt_dev_null = {
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   {
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     &alt_dev_list,
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     &alt_dev_list
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   },
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   "/dev/null",
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   NULL,               /* open */
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   NULL,               /* close */
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   NULL,               /* write */
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   alt_dev_null_write, /* write */
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   NULL,               /* lseek */
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   NULL,               /* fstat */
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   NULL                /* ioctl */
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 };
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/*
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 * "alt_fd_list_lock" is a semaphore used to control access to the file
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 * descriptor list. This is used to ensure that access to the list is thread
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 * safe.
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 */
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ALT_SEM(alt_fd_list_lock)
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/*
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 * "alt_max_fd" is used to make access to the file descriptor list more
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 * efficent. It is set to be the value of the highest allocated file
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 * descriptor. This saves having to search the entire pool of unallocated
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 * file descriptors when looking for a match.
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 */
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alt_32 alt_max_fd = -1;
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/*
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 * "alt_fd_list" is the file descriptor pool. The first three entries in the
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 * array are configured as standard in, standard out, and standard error. These
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 * are all initialised so that accesses are directed to the alt_dev_null
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 * device. The remaining file descriptors are initialised as unallocated.
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 *
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 * The maximum number of file descriptors within the system is specified by the
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 * user defined macro "ALT_MAX_FD". This is defined in "system.h", which is
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 * auto-genereated using the projects PTF and STF files.
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 */
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alt_fd alt_fd_list[ALT_MAX_FD] =
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  {
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    {
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      &alt_dev_null, /* standard in */
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      0,
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    },
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    {
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      &alt_dev_null, /* standard out */
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      0,
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    },
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    {
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      &alt_dev_null, /* standard error */
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      0,
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    }
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    /* all other elements are set to zero */
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  };

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