fat.c

基于UCOS-II制作的MP3

      {
        /* true DOS 8.3 entry format */
        for (i = 0; i < 8; i++)
        {
          lfn_name[i] = gl_buffer[i];
          
          if (lfn_name[i] == ' ')
          { /* space is end of name */
            break;
          }
        }
        /* append extension */
        lfn_name[i++] = '.';
        lfn_name[i++] = gl_buffer[8];
        lfn_name[i++] = gl_buffer[9];
        lfn_name[i++] = gl_buffer[10];

        for (; i != 14; i++)
        {
          lfn_name[i] = ' ';       /* append spaces for display reason */
        }
        lfn_name[i] = '\0';        /* end of string */
      }
        
      else
      { /* LFN name treatment */
        i = 0;
        /* search for the end of the string */
        while (lfn_name[i] != '\0')
        { 
          i++;
        }
        if (i <= 14)
        { /* append spaces for display reason (no scrolling) */
          while (i != 14)
          {
            lfn_name[i++] = ' ';
          }
        }
        else
        { /* append beginning of name to ease scrolling display */
          lfn_name[i++] = ' ';
          lfn_name[i++] = ' ';
          lfn_name[i++] = lfn_name[0];
          lfn_name[i++] = lfn_name[1];
          lfn_name[i++] = lfn_name[2];
          lfn_name[i++] = lfn_name[3];
          lfn_name[i++] = lfn_name[4];
          lfn_name[i++] = lfn_name[5];
          lfn_name[i++] = lfn_name[6];
          lfn_name[i++] = lfn_name[7];
          lfn_name[i++] = lfn_name[8];
          lfn_name[i++] = lfn_name[9];
          lfn_name[i++] = lfn_name[10];
          lfn_name[i++] = lfn_name[11];
          lfn_name[i++] = lfn_name[12];
        }
        lfn_name[i] = '\0';        /* end of name */
      }

      /* store extension */
      ext[0]= gl_buffer[8];
      ext[1]= gl_buffer[9];
      ext[2]= gl_buffer[10];

      /* standard computing for normal entry */
      entry->attributes = gl_buffer[11];
      entry->start_cluster = gl_buffer[26];
      entry->start_cluster += ((Uint16) gl_buffer[27]) << 8;
      entry->size.b[3] = gl_buffer[28];
      entry->size.b[2] = gl_buffer[29];
      entry->size.b[1] = gl_buffer[30];
      entry->size.b[0] = gl_buffer[31];
      /* now it's time to stop */
      exit_flag = TRUE;
    }
    else
    { /* LFN entry format */
      lfn_entry_found = TRUE;             /* a 8.3 name will follow */

      if ((gl_buffer[0] & LFN_SEQ_MASK) <= MAX_LFN_ENTRIES)   
      {                         /* Maximum number of entries for LFN? */
        for (i = 0; i < 5; i++)
		 {
	      song_name[i] = gl_buffer[2*i + 1]+gl_buffer[2*i + 1 + 1]*256;
          lfn_name[i + 13*((gl_buffer[0] & LFN_SEQ_MASK) - 1)] = gl_buffer[2*i + 1];
		  }
        for (i = 0; i < 6; i++)
		 {
		  song_name[i + 5] = gl_buffer[2*i + 14]+gl_buffer[2*i + 14 + 1]*256;
          lfn_name[i + 5 + 13*((gl_buffer[0] & LFN_SEQ_MASK) - 1)] = gl_buffer[2*i + 14];
		 }
        for (i = 0; i < 2; i++)
		 {
          lfn_name[i + 11 + 13*((gl_buffer[0] & LFN_SEQ_MASK) - 1)] = gl_buffer[2*i + 28];
		 }
      }
    }
  }  
  Hard_read_close();                        /* close physical read */
}


/*F**************************************************************************
* NAME: fat_get_dir_file_list
*----------------------------------------------------------------------------
* PARAMS:
*   id: file extension to select
*
* return:
*----------------------------------------------------------------------------
* PURPOSE:
*   Construct the file directory list
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   The value are relative position with the previous file.
*   Call to this function assume that the dir fragment chain has been created
*----------------------------------------------------------------------------
* REQUIREMENTS:
*   Maximum of 256 entries between 2 authorized file (id extension)
*   because the relative position is stored on one byte.
*   To allow more than 256 entries (-> 32768), change type of
*   fat_dir_entry_list[] from Byte to Uint16 (no overflow management)
*   and change MAX_DIRECTORY_GAP_FILE from 255 to 32767
*****************************************************************************/
void fat_get_dir_file_list (Byte id)
{
Uint16 index;                               /* chain index */
Uint16 counter_entry;                       /* entry counter: 0..MAX_DIRECTORY_FILE */
Uint16 entry_pos;                           /* relative entry position */
Uint16 entry_pos_saved;                     /* used when the file is not the id etension */
Byte   i;
   
  index = 0;
  fat_dir_list_last = 0;
  counter_entry = 0;
  entry_pos = 0;   
  fat_dir_start_sect = fat_dir_current_sect;
  fat_dir_current_offs = 0;

  Hard_read_open(fat_dir_start_sect);
  
  do /* scan all entries */
  {
    if (dir_is_root == TRUE)
    { /* root dir is linear -> Hard_read_byte() */
      for (i = 0; i < DIR_SIZE; i++)
        gl_buffer[i] = Hard_read_byte();
    }
    else
    { /* subdir can be fragmented -> dgetc() */
      for (i = 0; i < DIR_SIZE; i++)
        gl_buffer[i] = fat_dgetc();
    }
    counter_entry++;                          /* increase the # entry         */

    if ((gl_buffer[0] != FILE_DELETED) && (gl_buffer[0] != FILE_NOT_EXIST))
    { /* Existing file ? */ 
      fat_dir_entry_list[index] = entry_pos;  /* save the relative position   */

      entry_pos_saved = entry_pos;
      entry_pos = 1;                          /* reset the relative position  */
      index++;                                /* increase the index           */

      while (gl_buffer[11] == ATTR_LFN_ENTRY) /* LFN entry ?                  */
      {                                       /* then read all the LFN entry  */
        if (dir_is_root == TRUE)
        { /* root dir is linear -> Hard_read_byte() */
          for (i = 0; i < DIR_SIZE; i++)
            gl_buffer[i] = Hard_read_byte();
        }
        else
        { /* subdir can be fragmented -> dgetc() */
          for (i = 0; i < DIR_SIZE; i++)
            gl_buffer[i] = fat_dgetc();
        }

        counter_entry++;                    /* increase the # entry */
        entry_pos++;                        /* increase the relative position */
                                            /* for the next file */
      }

      /* filter on the file type */
      fat_cache.current.attributes = gl_buffer[11];
      ext[0] = gl_buffer[8];
      ext[1] = gl_buffer[9];
      ext[2] = gl_buffer[10];
      if ((fat_check_ext() & id) == FILE_XXX)
      {                                     /* Don't valid the entry */
        index--;                                              
        entry_pos += entry_pos_saved;
      }
    }
    else   /* Not an existing file */    
      entry_pos++;

    fat_dir_list_last = index;              /* update last file index */
    /* For sub-directory, there is no logical limit for the number of entries */
    /* In order to detect the last file, we check gl_buffer[0]                */
    /* We can put in the chain directory MAX_DIRECTORY_FILE selected file     */
    if (gl_buffer[0] == FILE_NOT_EXIST)
      index = MAX_DIRECTORY_FILE;
    /* Overflow of entry_pos */
    if (entry_pos > MAX_DIRECTORY_GAP_FILE)
      index = MAX_DIRECTORY_FILE;
    /* For Root directory, the maximum entries is 512!                        */
    if ((dir_is_root == TRUE) && (counter_entry == MAX_DIRECTORY_FILE))
      index = MAX_DIRECTORY_FILE;

    if (dir_is_root == FALSE)
    {
      /* check if we are at the end of the directory */
      if ((((Byte*)&fat_dclust_byte_count)[1] == 0x00) &&
      ((((Byte*)&fat_dclust_byte_count)[0] & fat_cluster_mask) == 0x00) && 
      (fat_last_dclust_index == fat_dchain_index))
        index = MAX_DIRECTORY_FILE;
    }
  }
  while (index < MAX_DIRECTORY_FILE);

  fat_dir_current_sect = fat_dir_start_sect;
  Hard_read_close();
}


/*F**************************************************************************
* NAME: fat_get_root_directory
*----------------------------------------------------------------------------
* PARAMS:
*   id: file extension to select
*
* return:
*   - OK: file available
*   - KO: no requested file found
*   - KO: low_level memory error
*----------------------------------------------------------------------------
* PURPOSE:
*   Select first available file/dir in root diretory
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   Fill all the cache information for the first time
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
bit fat_get_root_directory (Byte id)
{
  /* select first root dir entry */
  fat_dir_current_sect = fat_ptr_rdir;
  fat_dclust_byte_count = 0;
  dir_is_root = TRUE;

  fat_get_dir_file_list(id);                /* create list of entries */

  if (fat_dir_list_last == 0)
    return KO;                              /* no requested (id) entry */

  fat_dir_list_index = 0;                   /* point on first root entry */

  /* extract info from table */
  if (fat_dseek(fat_dir_entry_list[0] * DIR_SIZE) == OK)
  {
    fat_get_dir_entry(&fat_cache.current);  /* update current file info */
    /* parent dir is also root */
    fat_cache.parent.start_cluster = 0;   
    fat_cache.parent.attributes = ATTR_ROOT_DIR;  /* mark as root dir */
    return OK;
  }
  else
    return KO;                              /* low level error */
}


/*F**************************************************************************
* NAME: fat_goto_next
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*   - OK: next file available
*   - KO: last file reached
*   - KO: low_level memory error
*----------------------------------------------------------------------------
* PURPOSE:
*   Fetch the next dir/file info in cache
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 
bit fat_goto_next (void)
{
  
  if (fat_dir_list_index < (fat_dir_list_last - 1))
  {
    fat_dir_list_index++;
 
    if (fat_dseek((Int16)(fat_dir_entry_list[fat_dir_list_index ] * DIR_SIZE))== OK)
    { 
      fat_get_dir_entry(&fat_cache.current);/* update current file info */
      return OK;
    }
    else
      return KO;                            /* low level error */
  }
  else
    return KO;                              /* already on last file */
}


/*F**************************************************************************
* NAME: fat_goto_prev
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*   - OK: previous file available
*   - KO: first file reached
*   - KO: low_level memory error
*----------------------------------------------------------------------------
* PURPOSE:
*   Fetch the previous directory info in cache
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 
bit fat_goto_prev (void)
{
Byte min;
  
  if (dir_is_root)
    min = 0;
  else
    min = 2;

  if (fat_dir_list_index != min)            /* first file of the directory? */
  {
    if (fat_dseek((Int16)(fat_dir_entry_list[fat_dir_list_index] * (-DIR_SIZE))) == OK)
    { /* go to previous file */
      fat_dir_list_index--;
      fat_get_dir_entry(&fat_cache.current);/* update current file info */
      return OK;
    }
    else
      return KO;                            /* low level error */
  }
  else
    return KO;                              /* already on first file */
}

/*F**************************************************************************
* NAME: fat_seek_last
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*   OK: last file available
*   KO: low level error
*----------------------------------------------------------------------------
* PURPOSE:
*   Fetch the last directory info in cache
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 
bit fat_seek_last (void)
{
Uint16 gl_offset;
Uint16 i;