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[/] [ao486/] [trunk/] [syn/] [soc/] [firmware/] [exe_bsp/] [HAL/] [src/] [alt_lseek.c] - Blame information for rev 2

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/******************************************************************************
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*                                                                             *
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* License Agreement                                                           *
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*                                                                             *
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* Copyright (c) 2004-2005 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 <unistd.h>
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#include "sys/alt_errno.h"
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#include "sys/alt_warning.h"
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#include "priv/alt_file.h"
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#include "os/alt_syscall.h"
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#ifdef ALT_USE_DIRECT_DRIVERS
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off_t ALT_LSEEK (int file, off_t ptr, int dir)
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{
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  /* Generate a link time warning, should this function ever be called. */
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  ALT_STUB_WARNING(lseek);
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  /* Indicate an error */
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  ALT_ERRNO = ENOSYS;
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  return -1;
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}
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#else /* !ALT_USE_DIRECT_DRIVERS */
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/*
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 * lseek() can be called to move the read/write pointer associated with the
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 * file descriptor "file". This function simply vectors the call to the lseek()
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 * function provided by the driver associated with the file descriptor.
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 *
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 * If the driver does not provide an implementation of lseek() an error is
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 * indicated.
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 *
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 * lseek() corresponds to the standard lseek() function.
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 *
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 * ALT_LSEEK is mapped onto the lseek() system call in alt_syscall.h
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 *
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 */
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off_t ALT_LSEEK (int file, off_t ptr, int dir)
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{
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  alt_fd* fd;
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  off_t   rc = 0;
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  /*
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   * A common error case is that when the file descriptor was created, the call
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   * to open() failed resulting in a negative file descriptor. This is trapped
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   * below so that we don't try and process an invalid file descriptor.
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   */
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  fd = (file < 0) ? NULL : &alt_fd_list[file];
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  if (fd)
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  {
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    /*
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     * If the device driver provides an implementation of the lseek() function,
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     * then call that to process the request.
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     */
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    if (fd->dev->lseek)
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    {
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      rc = fd->dev->lseek(fd, ptr, dir);
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    }
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    /*
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     * Otherwise return an error.
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     */
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    else
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    {
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      rc = -ENOTSUP;
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    }
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  }
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  else
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  {
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    rc = -EBADFD;
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  }
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  if (rc < 0)
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  {
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    ALT_ERRNO = -rc;
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    rc = -1;
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  }
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  return rc;
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}
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#endif /* ALT_USE_DIRECT_DRIVERS */

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