fm_flt.c

FDI Intel开发的FLASH文件系统,功能很强大

 *    allocate the memory needed to maintain the table.
 *
 ****************************************************************************/

FLT_Error FLT_Create()
{
   /* reset the total number of entries in & search index into the FLT */
   NumFilesInFlt = 0;
   IndexIntoFlt  = 0;
/* E.5.2.870 BEGIN */
   NextIndexIntoFlt = 0;
/* E.5.2.870 END */
   return FLT_ErrorNone;
}



/*****************************************************************************
 *
 * FLT_Destroy
 *
 * DESCRIPTION:
 *    Releases all the resources obtained by the File Lookup Table during
 *    its lifetime.  When the File Lookup Table is created at boot time (as
 *    it is in this implementation), the function resets the variables needed
 *    to maintain the table.  When the File Lookup Table is created
 *    dynamically, the function releases all the memory it obtained during
 *    its lifetime.
 *
 ****************************************************************************/

FLT_Error FLT_Destroy()
{
   /* reset the total number of entries in & search index into the FLT */
   NumFilesInFlt = 0;
   IndexIntoFlt  = 0;
/* E.5.2.870 BEGIN */
   NextIndexIntoFlt = 0;
/* E.5.2.870 END */
   return FLT_ErrorNone;
}



/*****************************************************************************
 *
 * FLT_AddEntry
 *
 * DESCRIPTION:
 *    Adds a new mapping of a File Manager File to Data Manager Parameters.
 *
 ****************************************************************************/

FLT_Error FLT_AddEntry(
   const FDI_TCHAR *    filename,
   const UINT16         id
   )
{
   FLT_Error   error;
   UINT32      key;
   UINT16      index;
   FileLookup  entry;


   /* if memory is available to add the new entry to the FLT */
   if (NumFilesInFlt < NUM_FILES)
   {
      /* generate key based on the filename */
      key = GenerateKey(filename);

      /* create a new lookup table entry */
      CreateLookupTableEntry(&entry, key, id);

      /* add the new entry to the lookup table */
      error = AddToLookupTable(
                 FileLookupTable,
                 &NumFilesInFlt,
                 &index,
                 &entry
                 );

      /* update the search index if needed */
/* E.5.2.870 BEGIN */
      if ((error == FLT_ErrorNone) && (index <= IndexIntoFlt))
      {
         if (IndexIntoFlt < UINT16_MAX)
         {
            IndexIntoFlt++;
         }
         if (NextIndexIntoFlt < UINT16_MAX)
         {
            NextIndexIntoFlt++;
         }
      }
/* E.5.2.870 END */
   }
   else
   {
      /* declare there is not enough memory to add the entry */
      error = FLT_ErrorNotEnoughMemory;
   }

   return error;
}



/*****************************************************************************
 *
 * FLT_GetNumEntries
 *
 * DESCRIPTION:
 *    Returns the number of entries currently in the File Lookup Table.
 *
 ****************************************************************************/

UINT16 FLT_GetNumEntries()
{
   return NumFilesInFlt;
}



/*****************************************************************************
 *
 * FLT_GetEntryID
 *
 * DESCRIPTION:
 *    Determines the Data Manager ID of the File Manager File.
 *
 ****************************************************************************/

FLT_Error FLT_GetEntryID(
   UINT16 *           id,
   const FDI_TCHAR *  filename
   )
{
   FLT_Error   error;
   UINT32      key;
   FileLookup  entry;


   /* generate key based on the filename */
   key = GenerateKey(filename);

   /* lookup the entry */
   error = GetLookupTableEntry(
              &entry,
              key,
              filename,
              FileLookupTable,
              NumFilesInFlt
              );

   /* if the entry is present in the FLT */
   if (error == FLT_ErrorNone)
   {
      /* set the id to that of the entry's */
      *id = entry.Id;
   }

   return error;
}



/*****************************************************************************
 *
 * FLT_GetFirstEntryID
 *
 * DESCRIPTION:
 *    Returns the Data Manager Parameter ID of the first entry in the File
 *    Lookup Table.
 *
 ****************************************************************************/

FLT_Error FLT_GetFirstEntryID(
   UINT16 *    id
   )
{
   FLT_Error   error;


   /* set the index to the first entry */
   IndexIntoFlt = 0;

/* E.5.2.870 BEGIN */
   /* set the index to the next entry, if there is 0 or 1 entry, GetNextEtnry
    * will return false if NextIndexIntoFlt is too high */
   NextIndexIntoFlt = 1;
/* E.5.2.870 END */

   /* if the FLT has at least on entry */
   if (IndexIntoFlt < NumFilesInFlt)
   {
      /* set the id to the FLT's first entry's id and declare success */
      *id   = FileLookupTable[IndexIntoFlt].Id;
      error = FLT_ErrorNone;
   }
   else
   {
      /* declare no entries in the FLT */
      error = FLT_ErrorNoMoreEntries;
   }

   return error;
}



/*****************************************************************************
 *
 * FLT_GetNextEntryID
 *
 * DESCRIPTION:
 *    Returns the Data Manager Parameter ID of the next entry in the File
 *    Lookup Table.
 *
 ****************************************************************************/

FLT_Error FLT_GetNextEntryID(
   UINT16 *    id
   )
{
   FLT_Error   error;


   /* increment the FLT index to the next entry */
/* E.5.2.870 BEGIN */
   IndexIntoFlt = NextIndexIntoFlt;
/* E.5.2.870 END */

   /* if the FLT has at least one more entry to scan */
   if (IndexIntoFlt < NumFilesInFlt)
   {
      /* set the id to the FLT's next entry's id and declare success */
      *id   = FileLookupTable[IndexIntoFlt].Id;
      error = FLT_ErrorNone;

/* E.5.2.870 BEGIN */
      /* Set index to next entry. NextIndexIntoFlt will continue being
       * incremented until it is equal to NumFilesInFlt */
      NextIndexIntoFlt++;
/* E.5.2.870 END */
   }
   else
   {
      /* declare there are no more entries */
      error = FLT_ErrorNoMoreEntries;
   }

   return error;
}



/*****************************************************************************
 *
 * FLT_GetFirstEntryName
 *
 * DESCRIPTION:
 *    Returns the File Manager filename of the first entry in the File
 *    Lookup Table.
 *
 ****************************************************************************/

FLT_Error FLT_GetFirstEntryName(
   FDI_TCHAR *    filename
   )
{
   FLT_Error   error;
   FILE_INFO   file_info;


   /* Set the index into the FLT*/
   IndexIntoFlt = 0;

/* E.5.2.870 BEGIN */
   /* set the index to the next entry, if there is 0 or 1 entry, GetNextEtnry
    * will return false if NextIndexIntoFlt is too high */
   NextIndexIntoFlt = 1;
/* E.5.2.870 END */

   /* if a single entries exists */
   if (IndexIntoFlt < NumFilesInFlt)
   {
      /* if a read from flash was successful */
      error = ReadFileInfo(&file_info, FileLookupTable[IndexIntoFlt].Id);
      if (error == FLT_ErrorNone)
      {
         /* return the filename */
         FM_CopyString(filename, file_info.file_name, (FILE_NAME_SIZE + 1));
      }
   }
   else
   {
      /* declare there are no entries in the FLT */
      error = FLT_ErrorNoMoreEntries;
   }

   return error;
}



/*****************************************************************************
 *
 * FLT_GetNextEntryName
 *
 * DESCRIPTION:
 *    Returns the File Manager filename of the next entry in the File
 *    Lookup Table.
 *
 ****************************************************************************/

FLT_Error FLT_GetNextEntryName(
   FDI_TCHAR *    filename
   )
{
   FLT_Error   error;
   FILE_INFO   file_info;


   /* increment the index into the FLT */
/* E.5.2.870 BEGIN */
   IndexIntoFlt = NextIndexIntoFlt;
/* E.5.2.870 END */

   /* if at least one more entry exists */
   if (IndexIntoFlt < NumFilesInFlt)
   {
      /* read the filename from flash */
      error = ReadFileInfo(&file_info, FileLookupTable[IndexIntoFlt].Id);
      if (error == FLT_ErrorNone)
      {
         /* return the filename */
         FM_CopyString(filename, file_info.file_name, (FILE_NAME_SIZE + 1));
/* E.5.2.870 BEGIN */
         NextIndexIntoFlt++;
/* E.5.2.870 END */
      }
   }
   else
   {
      /* declare there are no entries in the FLT */
      error = FLT_ErrorNoMoreEntries;
   }

   return error;
}



/*****************************************************************************
 *
 * FLT_DeleteEntryByID
 *
 * DESCRIPTION:
 *    Deletes the entry whose Data Manager Parameter ID matches the value
 *    specified.
 *
 ****************************************************************************/

FLT_Error FLT_DeleteEntryByID(
   const UINT16 id
   )
{
   FLT_Error error;
   UINT16    index;

   /* if there are entries in the FLT */
   if (NumFilesInFlt > 0)
   {
      /* attempt to remove the entry with the specified id */
      error = DeleteFromLookupTable(
                 FileLookupTable,
                 &NumFilesInFlt,
                 &index,
                 id
                 );

      /* update search index if needed */
/* E.5.2.870 BEGIN */
      if ((error == FLT_ErrorNone) &&
          (index <= IndexIntoFlt))
      {
         if(IndexIntoFlt > 0)
         {
            IndexIntoFlt--;
         }
         if(NextIndexIntoFlt > 0)
         {
            NextIndexIntoFlt--;
         }
      }
/* E.5.2.870 END */
   }
   else
   {
      /* declare entry does not exist */
      error = FLT_ErrorEntryDoesNotExist;
   }

   return error;
}

#endif /* FILE_MANAGER == TRUE */