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

*                                                                             *

* License Agreement                                                           *

*                                                                             *

* Copyright (c) 2006 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 <unistd.h>

#include <fcntl.h>

#include "sys/alt_errno.h"

#include "sys/alt_warning.h"

#include "priv/alt_file.h"

#include "os/alt_syscall.h"

/*

 * The read() system call is used to read a block of data from a file or device.

 * This function simply vectors the request to the device driver associated

 * with the input file descriptor "file".

 *

 * ALT_READ is mapped onto the read() system call in alt_syscall.h

 */

#ifdef ALT_USE_DIRECT_DRIVERS

#include "system.h"

#include "sys/alt_driver.h"

/*

 * Provide minimal version that just reads from the stdin device when provided.

 */

int ALT_READ (int file, void *ptr, size_t len)

{

#ifdef ALT_STDIN_PRESENT

    ALT_DRIVER_READ_EXTERNS(ALT_STDIN_DEV);

#endif

#if !defined(ALT_STDIN_PRESENT)

    /* Generate a link time warning, should this function ever be called. */

    ALT_STUB_WARNING(read);

#endif

    switch (file) {

#ifdef ALT_STDIN_PRESENT

    case 0: /* stdin file descriptor */

        return ALT_DRIVER_READ(ALT_STDIN_DEV, ptr, len, 0);

#endif /* ALT_STDIN_PRESENT */

    default:

        ALT_ERRNO = EBADFD;

        return -1;

    }

}

#else /* !ALT_USE_DIRECT_DRIVERS */

int ALT_READ (int file, void *ptr, size_t len)

{

  alt_fd*  fd;

  int      rval;

  /*

   * A common error case is that when the file descriptor was created, the call

   * to open() failed resulting in a negative file descriptor. This is trapped

   * below so that we don't try and process an invalid file descriptor.

   */

  fd = (file < 0) ? NULL : &alt_fd_list[file];

  if (fd)

  {

    /*

     * If the file has not been opened with read access, or if the driver does

     * not provide an implementation of read(), generate an error. Otherwise

     * call the drivers read() function to process the request.

     */

    if (((fd->fd_flags & O_ACCMODE) != O_WRONLY) &&

        (fd->dev->read))

      {

        if ((rval = fd->dev->read(fd, ptr, len)) < 0)

        {

          ALT_ERRNO = -rval;

          return -1;

        }

        return rval;

      }

      else

      {

        ALT_ERRNO = EACCES;

      }

    }

  else

  {

    ALT_ERRNO = EBADFD;

  }

  return -1;

}

#endif /* ALT_USE_DIRECT_DRIVERS */