fat.c

基于UCOS-II制作的MP3

  for (i = fat_dir_list_index + 1, gl_offset = 0; i < fat_dir_list_last; fat_dir_list_index++, i++)
    gl_offset += fat_dir_entry_list[i];

  if (fat_dseek(gl_offset * DIR_SIZE) == OK)
  {
    fat_get_dir_entry(&fat_cache.current);      
    return OK;
  }
  else
    return KO;                              /* low level error */
}

/*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)
{
Uint16 gl_offset = 0;
Uint16 i;
  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_dir_current_offs = 0;                 /* reset the global offset */

  for (i = 0; i <= fat_dir_list_index; i++)
    gl_offset += fat_dir_entry_list[i];

  return fat_dseek(gl_offset * DIR_SIZE);
}

/*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_dir_current_offs = 0;                 /* reset the global offset */

  if (dir_is_root)
  { /* root diretory */
    fat_dir_list_index = 0;                 /* point first root entry */
    if (fat_dseek((Int16)(fat_dir_entry_list[0] * DIR_SIZE)) == OK)
    {
      fat_get_dir_entry(&fat_cache.current);/* update first file info */      
      return OK;
    }
    else
    {
      return KO;                            /* low level error */
    }
  }
  else
  { /* not root dir */
    fat_dir_list_index = 1;                 /* point ".." entry */
    if (fat_dseek((Int16)(fat_dir_entry_list[1] * DIR_SIZE)) == OK)
    {
      fat_get_dir_entry(&fat_cache.parent); /* update parent dir info */
      return fat_goto_next();               /* update first file info */
    }
    else
      return KO;                            /* low level error */
  }
}


/*F**************************************************************************
* NAME: fat_goto_subdir
*----------------------------------------------------------------------------
* PARAMS:
*   id: file extension to select
*
* return:
*   - OK: subdir selected
*   - KO: current entry not a directory
*   - KO: no file in subdir
*   - 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 != 0)
    { /* go to not root dir */ 
      dir_is_root = FALSE;                  /* not the root dir */
      /* get directory allocation table */
      fat_get_clusters(&dclusters, MAX_DIR_FRAGMENT_NUMBER);

      /* Save last index position for chain cluster */
      fat_last_dclust_index = fat_last_clust_index;
      /* initialize fat pointers */
      fat_dchain_nb_clust = 0;
      fat_dchain_index = 0;
      fat_dclust_byte_count = 0;
                          
      /* computes sector address from allocation table */
      fat_dir_current_sect = (((Uint32)(dclusters[0].cluster)) * fat_cluster_size)
                           + fat_ptr_data;
    }
    else
    { /* go to root dir */
      return fat_get_root_directory(id);
    }

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

    fat_dir_list_index = 1;                 /* point ".." entry */
    if (fat_dseek((Int16)(fat_dir_entry_list[1] * DIR_SIZE)) == OK)
    {
      fat_get_dir_entry(&fat_cache.parent); /* update parent dir info */
      return fat_goto_next();               /* update first file info */
    }
    else
      return KO;                            /* low level error */
  }
  else
    return KO;                              /* current entry is not a dir */
}
  

/*F**************************************************************************
* NAME: fat_goto_parentdir
*----------------------------------------------------------------------------
* PARAMS: 
*   id: file extension to select
*
* return:
*   status: OK: parent_dir selected
*           KO: no parent dir (root)
*----------------------------------------------------------------------------
* PURPOSE:
*   Go to the parent directory
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   File pointed is sub-dir if parent dir is not root or first file if root
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 
bit fat_goto_parentdir (Byte id)
{ 
Uint16 temp_cluster;

  if (dir_is_root)
  { /* already in root dir */
    fat_seek_first();                       /* point on first file */
    return KO;
  }
  else
  { /* not in root dir */
    temp_cluster = dclusters[0].cluster + 2;/* save cluster info */
    fat_cache.current = fat_cache.parent;  /* goto the parent directory */

    /* issue the equivalent to a cd .. DOS command */
    if (fat_goto_subdir(id))
    { /* reselect the dir entry in list */
      while (temp_cluster != fat_cache.current.start_cluster)
      {
        if (fat_goto_next() == KO)
          break;
      }
      if (temp_cluster == fat_cache.current.start_cluster)
        return OK;
      else
        return KO;
    }
    else
    {
      return KO;
    }
  }
}


/*F**************************************************************************
* NAME: fat_update_fat_sector
*----------------------------------------------------------------------------
* PARAMS: 
*   sector_number : fat sector position
*
* return:
*----------------------------------------------------------------------------
* PURPOSE:
*   update a sector of fat
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*   This function check if there is 2 fats to be updated
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/  
void fat_update_fat_sector (Uint16 sector_number)
{
Uint16 i;

  /* FAT 1 update */
  Hard_write_open(fat_ptr_fats + sector_number);
  for (i = 0; i < SECTOR_SIZE; i++)
    Hard_write_byte(fat_buf_sector[i]);
  Hard_write_close();
  if (fat_2_is_present == TRUE)
  {
    /* FAT 2 update */
    Hard_write_open(fat_ptr_fats + sector_number + fat_fat_size);
    for (i = 0; i < SECTOR_SIZE; i++)
      Hard_write_byte(fat_buf_sector[i]);
    Hard_write_close();
  }      
}


    

   
/*F**************************************************************************
* NAME: fat_update_buf_fat
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*----------------------------------------------------------------------------
* PURPOSE:
*   This function check if a fat sector have to be writen.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*   fat_root_entry must be updated.
*****************************************************************************/
void fat_update_buf_fat(Uint16 cluster_old, Uint16 cluster, bit end)
{
bit fat_12_parity;
Byte sector_number;
#define i cluster_old

  fat_12_parity = ((Byte*)&cluster_old)[1] & 0x01;
  sector_number = cluster_old * 3 / 1024;
  i = (cluster_old * 3 / 2) & 0x1FF;

  if (end == TRUE)
    cluster = 0xFFF;
  if (fat_12_parity == 0)
  {
    fat_buf_sector[i++] = ((Byte*)&cluster)[1];
    if (((Byte*)&i)[0] == 0x02)
    {
      fat_update_fat_sector(sector_number); 
      sector_number++;
      fat_load_sector(fat_ptr_fats + sector_number);
      ((Byte*)&i)[0] = 0x00;
    }
    fat_buf_sector[i] &= 0xF0;
    fat_buf_sector[i] |= ((Byte*)&cluster)[0] & 0x0F;
  }
  else
  {
    fat_buf_sector[i] &= 0x0F;
    fat_buf_sector[i] |= (((Byte*)&cluster)[1] & 0x0F) << 4;
    i++;
    if (((Byte*)&i)[0] == 0x02)
    {
      fat_update_fat_sector(sector_number); 
      sector_number++;
      fat_load_sector(fat_ptr_fats + sector_number);
      ((Byte*)&i)[0] = 0x00;
    }
    fat_buf_sector[i++] = (cluster & 0x0FF0) >> 4;
    if (((Byte*)&i)[0] == 0x02)
    {
      fat_update_fat_sector(sector_number); 
      sector_number++;
      fat_load_sector(fat_ptr_fats + sector_number);
      ((Byte*)&i)[0] = 0x00;
    }
  }
  if (end == TRUE)
    fat_update_fat_sector(sector_number);
  #undef i

}
/*F**************************************************************************
* NAME: fat_update_entry_fat
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*----------------------------------------------------------------------------
* PURPOSE:
*   Update root entry and FAT after a writing file session (create or re-write)
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*   fat_root_entry must be updated.
*****************************************************************************/
void fat_update_entry_fat (void)
{
Byte index;
Byte chain_index;
Byte sector_number;
Uint16 i;
Uint16 cluster;
Uint16 nb_cluster;

/*********************/
/* Update root entry */
/*********************/
  fat_load_sector(fat_ptr_rdir + (fat_root_entry >> 4));
  i = (fat_root_entry % 16) * 32 ;               /* Position of entry in the sector */
  /* Update file size */
  if (fat_cache.current.size.l <= fat_file_size.l)
    fat_cache.current.size.l = fat_file_size.l;
  fat_buf_sector[i + 28] = fat_cache.current.size.b[3];
  fat_buf_sector[i + 29] = fat_cache.current.size.b[2];
  fat_buf_sector[i + 30] = fat_cache.current.size.b[1];
  fat_buf_sector[i + 31] = fat_cache.current.size.b[0];

  ext[0] = fat_buf_sector[i + 8];
  ext[1] = fat_buf_sector[i + 9];
  ext[2] = fat_buf_sector[i + 10];
  

  Hard_write_open(fat_ptr_rdir + (fat_root_entry >> 4));
  for (i= 0; i< SECTOR_SIZE; i++)
    Hard_write_byte(fat_buf_sector[i]);
  Hard_write_close();