fat32.c

基于AT89C51SND1的MP3的程序设计(包括播放mp3和录音功能)

        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 */      
    }
    else
    {
      /* 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;
        }
      }
      if ((gl_buffer[8] == ' ') &&
          (gl_buffer[9] == ' ') &&
          (gl_buffer[10] == ' '))
        lfn_name[i++] = ' ';
      else
        lfn_name[i++] = '.';                                  /* append extension */
      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 */
    } 
    fat_cache.current.attributes = gl_buffer[11];       /* filter on the file type */
    
    ext[0]= gl_buffer[8];                                   /* store extension */
    ext[1]= gl_buffer[9];
    ext[2]= gl_buffer[10];

    fat_current_end_entry_position++;
    if ((fat_check_ext() & current_ext) == FILE_XXX)
    {
      fat_dir_current_offs += ((fat_current_end_entry_position - fat_current_start_entry_position) << 5);  
    }
  }
  while ((fat_check_ext() & current_ext) == FILE_XXX);


  entry->start_cluster  = gl_buffer[26];                    /* starting cluster value */
  entry->start_cluster += ((Uint32) gl_buffer[27]) << 8;
  entry->start_cluster += ((Uint32) gl_buffer[20]) << 16;
  entry->start_cluster += ((Uint32) gl_buffer[21]) << 24;
  entry->size.b[3]      = gl_buffer[28];                    /* file size value        */
  entry->size.b[2]      = gl_buffer[29];
  entry->size.b[1]      = gl_buffer[30];
  entry->size.b[0]      = gl_buffer[31];
  Hard_read_close();                                        /* close physical read */

}


/*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)
{
  dir_is_root = TRUE;                                       /* set directory root flag */
  fat_cache.current.start_cluster = fat_rootclus_fat32 ;    /* #cluster root directory */
  fat_get_clusters(&dclusters, MAX_DIR_FRAGMENT_NUMBER);    /* Construct root directory cluster chain */
  fat_last_dclust_index = fat_last_clust_index;             /* save last index position for chain cluster */

                      
  /* computes sector address from allocation table */
  fat_dir_current_sect = (((Uint32)(dclusters[0].cluster)) * fat_cluster_size)
                       + fat_ptr_data;

  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 = 1;                                   /* point on first root entry */
  fat_current_start_entry_position = 0;
  fat_current_end_entry_position = 0;
  fat_fetch_file_info(&fat_cache.current, FETCH_NEXT);
  fat_cache.parent.start_cluster = fat_rootclus_fat32;    /* parent dir is also root */   
  fat_cache.parent.attributes = ATTR_DIRECTORY;           /* mark as directory */
  return OK;
}


/*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)
  {
    fat_dir_list_index++;
    fat_fetch_file_info(&fat_cache.current, FETCH_NEXT);
    return OK;
  }
  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 = 1;
  else
    min = 3;

  if (fat_dir_list_index != min)            /* first file of the directory? */
  {
    fat_dir_list_index--;
    fat_fetch_file_info(&fat_cache.current, FETCH_PREV);
    return OK;
  }
  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)
{
bit result;
  do
  {
    result = fat_goto_next();
  }
  while (result == OK);
  return result;
}

/*F**************************************************************************
* NAME: fat_seek_entry_record
*----------------------------------------------------------------------------
* PARAMS:
*   fat_dir_list_index : # of the fetched entry
*   
* return:
*   OK: file available
*   KO: low level error
*----------------------------------------------------------------------------
* PURPOSE:
*   Fetch the selected entry
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 
bit fat_seek_entry_record (void)
{
bit result;
Uint16 temp;

  temp = fat_dir_list_index - 1;
  fat_seek_first();
  for (; temp != 0; temp--)
    result = fat_goto_next();
  return result;
}

/*F**************************************************************************
* NAME: fat_seek_first
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*   - OK: first file found
*   - KO: low level error
*----------------------------------------------------------------------------
* PURPOSE:
*   Fetch the first directory info in cache
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 
bit fat_seek_first (void)
{
  fat_clear_dir_info(); 
  fat_dir_current_sect = fat_dir_start_sect;
  fat_current_start_entry_position = 0;
  fat_current_end_entry_position = 0;

  if (dir_is_root)
  { /* root diretory */
    fat_dir_list_index = 1;                         
    fat_fetch_file_info(&fat_cache.current, FETCH_NEXT);  /* fetch first root entry */
    return OK;
  }
  else
  { /* not root dir */
    fat_fetch_file_info(&fat_cache.parent, FETCH_NEXT);   /* dot entry          */
    fat_fetch_file_info(&fat_cache.parent, FETCH_NEXT);   /* dotdot entry       */
    fat_dir_list_index = 2;                               /* update entry index */
    return fat_goto_next();                               /* update first file info */
  }
}


/*F**************************************************************************
* NAME: fat_goto_subdir
*----------------------------------------------------------------------------
* PARAMS:
*   id: file extension to select
*
* return:
*   - OK: subdir selected
*   - KO: current entry not a directory
*   - KO: low level error
*----------------------------------------------------------------------------
* PURPOSE:
*   Go to the subdir if current is a directory
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   Also called by goto_parentdir() with current info from parent info
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 
bit fat_goto_subdir (Byte id)
{                        
  /* check if current file is a directory */
  if ((fat_cache.current.attributes & ATTR_DIRECTORY) == ATTR_DIRECTORY)
  {
    /* computes the sector address (RELATIVE) */
    if (fat_cache.current.start_cluster == fat_rootclus_fat32)
    {
      return fat_get_root_directory(id);                    /* go to root dir */
    }

    /* go to not root dir */ 
    fat_get_clusters(&dclusters, MAX_DIR_FRAGMENT_NUMBER);  /* get directory allocation table */                                         
    fat_last_dclust_index = fat_last_clust_index;           /* save last index position for chain cluster */
    fat_dir_current_sect = (((Uint32)(dclusters[0].cluster)) * fat_cluster_size)    /* computes sector address from allocation table */
                           + fat_ptr_data;

    fat_get_dir_file_list(id);                              /* create list of entries */
    fat_dir_list_index = 1;                                 /* point on first root entry */
    fat_current_start_entry_position = 0;
    fat_current_end_entry_position = 0;    
    
    fat_fetch_file_info(&fat_cache.current, FETCH_NEXT);    /* dot entry    */   
    fat_fetch_file_info(&fat_cache.parent, FETCH_NEXT);     /* dotdot entry */
    fat_dir_list_index = 2;                                 /* update index position entry */
    if(fat_cache.parent.start_cluster == 0x00)              /* if parent dir is root */
    {
      fat_cache.parent.start_cluster = fat_rootclus_fat32;  /* then update start cluster value */
    }
    dir_is_root = FALSE;
    return fat_goto_next();
  }
  else
    return KO;                                /* current entry is not a dir */
}
  

/*F**************************************************************************
* NAME: fat_goto_parentdir
*----------------------------------------------------------------------------
* PARAMS: 
*   id: file extension to select
*
* return:
*----------------------------------------------------------------------------
* PURPOSE:
*   Go to the parent directory
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------