fat.c

基于UCOS-II制作的MP3

  cluster = fclusters[0].cluster + 2;
  /* Start at first chain cluster */
  sector_number = (fat_is_fat16 == TRUE) ? cluster / 256 : cluster * 3 / 1024;
  /* Bufferize fat sector */
  fat_load_sector(fat_ptr_fats + sector_number);
  end = FALSE;
  do 
  {
    temp = (fat_is_fat16 == TRUE) ? cluster / 256 : cluster * 3 / 1024;
    if (temp != sector_number)
    {
      fat_update_fat_sector(sector_number);
      sector_number =  temp;
      fat_load_sector(fat_ptr_fats + sector_number);
    }
    if (fat_is_fat16 == TRUE)
    {
      i = (cluster * 2) & 0x1FF;
      ((Byte *)&cluster)[1] = fat_buf_sector[i];
      fat_buf_sector[i++] = 0;
      ((Byte *)&cluster)[0] = fat_buf_sector[i];
      fat_buf_sector[i] = 0;
      end = (cluster == 0xFFFF);
    }
    else
    {
      i = (cluster * 3 / 2) & 0x1FF;
      if ((cluster & 0x01) == 0)
      {
        ((Byte *)&cluster)[1] = fat_buf_sector[i];
        fat_buf_sector[i] = 0x00;
        i++;
        if (i == 512)
        {
          fat_update_fat_sector(sector_number);
          sector_number++;
          fat_load_sector(fat_ptr_fats + sector_number);
          i = 0;
        }
        ((Byte *)&cluster)[0] = fat_buf_sector[i] & 0x0F;
        fat_buf_sector[i] &= 0xF0;
      }
      else
      {
        cluster = (fat_buf_sector[i] & 0xF0) >> 4;
        fat_buf_sector[i] &=  0x0F;
        i++;
        if (i == 512)
        {
          fat_update_fat_sector(sector_number);
          sector_number++;
          fat_load_sector(fat_ptr_fats + sector_number);
          i = 0;
        }
        cluster += (fat_buf_sector[i] << 4);
        fat_buf_sector[i] = 0x00;
      }
      end = (cluster == 0xFFF);

    }

  }
  while (!end);
  fat_update_fat_sector(sector_number);
}


/*F**************************************************************************
* NAME: fat_refresh_dir_file_info
*----------------------------------------------------------------------------
* PARAMS:
*    
* return:
*   
*----------------------------------------------------------------------------
* PURPOSE:
*   Reconstruct the file directory list and seek to the file pointed by
*   fat_dir_list_index
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   
*----------------------------------------------------------------------------
* REQUIREMENTS:
*   
*****************************************************************************/
void fat_refresh_dir_file_info (Byte id)
{
  /* update fat_dir_current_sect with directory starting value */
  if (dir_is_root)
  {
    fat_dir_current_sect = fat_ptr_rdir;                          
  }
  else
  {
    fat_dir_current_sect = (((Uint32)(dclusters[0].cluster)) * fat_cluster_size)
                           + fat_ptr_data;
  }

  fat_get_dir_file_list(id);                /* Refresh file list */
  fat_seek_entry_record();                  /* Re-fetch the entry <-> fat_dir_list_index */
  fat_get_dir_entry(&fat_cache.current);    /* update current file info */  
}


/*F**************************************************************************
* NAME: fat_fdelete
*----------------------------------------------------------------------------
* PARAMS:
*    
* return:
*   - DEL_RET_OK:           delete done & dir is not empty
*   - DEL_RET_NO_MORE_FILE: dir is empty after delete or not
*   - DEL_RET_ERROR_DIR:    dir can not be deleted
*----------------------------------------------------------------------------
* PURPOSE:
*   Delete a selected file, in the root directory or in a sub-dir
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   fat_frefresh may be called after fdelete to rebuilt the dir content list
*----------------------------------------------------------------------------
* REQUIREMENTS:
*   File variables must be updated (fat_dclust_byte_count, entry record, ...)
*****************************************************************************/
Byte fat_fdelete (void)
{
Uint16 i;
Uint32 dir_sector; 

  if (((dir_is_root == TRUE) && (fat_dir_list_last == 0)) ||     
      ((dir_is_root == FALSE) && (fat_dir_list_last == 2)))      /* . and .. directory */
    return DEL_RET_NO_MORE_FILE;            /* directory already empty */

  if (fat_check_ext() != FILE_DIR)
  {
    fat_seek_entry_record();                /* Re-fetch the entry <-> fat_dir_list_index */
    Hard_read_close();

    dir_sector = fat_dir_current_sect;
    fat_root_entry = fat_dir_current_offs / 32; /* fat_dir_current_offs give the offset in byte starting */
    fat_file_size.l = fat_cache.current.size.l; /* at the beginning of directory */

    fat_load_sector(dir_sector);            /* Load directory sector  */
    i = (fat_root_entry % 16) * 32 ;        /* position of entry in the sector */
    while (fat_buf_sector[i + 11] == ATTR_LFN_ENTRY)
    {
      /* mark file as deleted */
      fat_buf_sector[i] = FILE_DELETED;
      i += 32;

      if (!dir_is_root)
        fat_dclust_byte_count += 32;

      if (i == SECTOR_SIZE)
      {
        Hard_write_open(dir_sector);
        for (i = 0; i < SECTOR_SIZE; i++)
          Hard_write_byte(fat_buf_sector[i]);
        Hard_write_close();

        if (!dir_is_root)                   /* sub-directory */
        {
          /* check if we are at the end of a cluster */
          if ((((Byte*)&fat_dclust_byte_count)[1] == 0x00) &&
            ((((Byte*)&fat_dclust_byte_count)[0] & fat_cluster_mask) == 0x00))
          {
            /* extract if necessary the next cluster from the allocation list */
            if (dclusters[fat_dchain_index].number == fat_dchain_nb_clust)
            { /* new fragment */
              fat_dchain_index++;
              fat_dchain_nb_clust = 1;
              dir_sector = (fat_ptr_data + ((Uint32)(dclusters[fat_dchain_index].cluster) * fat_cluster_size));
            }
            else
            {
              fat_dchain_nb_clust++;        /* one more cluster read */
              dir_sector++;                 /* Contiguous cluster    */
            }
          }
          else
          { /* Don't change the cluster */
            dir_sector++;
          }
        }
        else
        { /* Root directory is linear */
          dir_sector++;
        }
        fat_load_sector(dir_sector);
        i = 0;
      }
    }
    fat_buf_sector[i] = FILE_DELETED;
    Hard_write_open(dir_sector);
    for (i = 0; i < SECTOR_SIZE; i++)
      Hard_write_byte(fat_buf_sector[i]);
    Hard_write_close();

    /* FAT update */
    fat_fclust_byte_count = 0;              /* byte 0 of cluster */
    /* reset the allocation list variable */
    fat_fchain_index = 0;
    fat_fchain_nb_clust = 0;                /* start on first contiguous cl */
    /* get file allocation list */
    fat_get_clusters(&fclusters, MAX_FILE_FRAGMENT_NUMBER);
    /* Clear fat cluster */
    fat_clear_fat();
    /* NF correction */
    for (i = 0; i < 256; i++)
      gl_buffer[i] = 0x00;
    fat_dir_list_last--;                    /* one file deleted */

    if (((dir_is_root == TRUE) && (fat_dir_list_last == 0)) ||     
        ((dir_is_root == FALSE) && (fat_dir_list_last == 2)))      /* . and .. directory */
      return DEL_RET_NO_MORE_FILE;          /* directory now empty */

    if (fat_dir_list_index == fat_dir_list_last)
    {
      fat_dir_list_index--;                 /* in case of last file delete */
    }
    return DEL_RET_OK;
  }
  else
  {
    return DEL_RET_ERROR_DIR;
  }
}

/*F**************************************************************************
* NAME: fat_free_space
*----------------------------------------------------------------------------
* PARAMS:
*   
* return:
*   number of free cluster
*----------------------------------------------------------------------------
* PURPOSE:
*   Get free space   
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
fat_st_free_space fat_free_space(void)
{
Uint32 temp;
Uint32 i;
Uint16 cluster;
bdata bit fat12_parity;
xdata fat_st_free_space free_space;

  Hard_read_open(fat_ptr_fats);
  temp = 2;
  if (fat_is_fat16)     /* FAT16 management */
  {
    for (i = 0; i < fat_count_of_clusters; i++)
    {
      ((Byte*)&cluster)[1] = Hard_read_byte();
      ((Byte*)&cluster)[0] = Hard_read_byte();
      if (cluster == 0x0000)
        temp++;
    }
    Hard_read_close();
    free_space.free_cluster = temp;
    free_space.cluster_size = fat_cluster_size; 
    return free_space;
  }
  else
  {
    fat12_parity = 0;
    for (i = 0; i < fat_count_of_clusters; i++)
    {
      if (fat12_parity == 0)
      {
        ((Byte*)&cluster)[1] = Hard_read_byte();
        ((Byte*)&cluster)[0] = Hard_read_byte();
        fat12_parity = 1;
      }
      else
      {
        cluster = (cluster & 0xF000) >> 12;
        cluster += (Hard_read_byte() << 4);
        fat12_parity = 0;
      }
      if (!(cluster & 0x0FFF))
        temp++;
    }
    Hard_read_close();
    free_space.free_cluster = temp;
    free_space.cluster_size = fat_cluster_size; 
    return free_space;
  }
}


/*F**************************************************************************
* NAME: fat_read_cluster12
*----------------------------------------------------------------------------
* PARAMS:
*   init : initialize the parity bit or not
* return:
*   FAT12 cluster value
*----------------------------------------------------------------------------
* PURPOSE:
*   Read in fat12 file system a cluster value   
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
Uint16 fat_read_cluster (bit init)
{
static bit fat12_parity;
static idata Uint16 cluster;

  if (fat_is_fat16)
  {
    ((Byte*)&cluster)[1] = Hard_read_byte();
    ((Byte*)&cluster)[0] = Hard_read_byte();
    return cluster;
  }

  if (init)
  {
    fat12_parity = 0;
    cluster = 0;
  }

  if (fat12_parity == 0)
  {
    ((Byte*)&cluster)[1] = Hard_read_byte();
    ((Byte*)&cluster)[0] = Hard_read_byte();
    fat12_parity = 1;
    return (cluster & 0x0FFF);
  }
  else
  {
    cluster = (cluster & 0xF000) >> 12;
    cluster += (Hard_read_byte() << 4);
    fat12_parity = 0;
    return (cluster);
  }
}


/*F**************************************************************************
* NAME: fat_set_clusters
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*   - OK: allocation done
*   - KO: allocation cannot be done : no free cluster
*----------------------------------------------------------------------------
* PURPOSE:
*   Prepare a list of the free clusters:
*     chain[n].cluster contains the starting cluster number of a fragment
*     chain[n].number contains the number of contiguous clusters in fragment
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   Free cluster list is limited by the nb_frag parameter.
*   If memory is too much fragmented, created file may be limited in size.
*   Last list item always has single cluster
*----------------------------------------------------------------------------
* REQUIREMENTS:
************************