fat_file.c

fat16文件系统源码。需要的请下

  		old_cluster = new_cluster;

  		if (index == nb_frag)
  		{ /* end of chain reached */
   		 	/* last fragment always contains a single cluster */
    		chain[nb_frag].number = 0;          /* end of chain marker */
    		fat_last_clust_index = nb_frag;
    		return  KO;                         /* file too much fragmented */
  		}
  		else
  		{
    		/* read new entry */
      		//((Byte *)&new_cluster)[1]= gl_buffer[0+fat_buf_count];
	  		//((Byte *)&new_cluster)[0]= gl_buffer[1+fat_buf_count];
	  		
	  		new_cluster = fat_U8_to_U16_LH(gl_buffer[fat_buf_count], gl_buffer[fat_buf_count + 1]);
  		}
	}	

	fat_last_clust_index = index;
//	fat_get_clusters_end(chain,index);
	return OK;
}
#endif //COMPILE_FAT_16



//////////////////////////////////////////////////////////////////////////////////
//
//
//
//
//
//////////////////////////////////////////////////////////////////////////////////
byte fat_get_clusters (fat_st_clust_chain  *chain, Byte nb_frag)
{
	if(fat_type_id == FAT_IS_16)
	{
        #if COMPILE_FAT_16 == TRUE
		if(fat16_get_clusters (chain,  nb_frag) == KO)
			return KO;	
        #endif
	}
	else if(fat_type_id == FAT_IS_12)
	{
        #if COMPILE_FAT_12 == TRUE	
	    if(fat12_get_clusters (chain,  nb_frag) == KO)
			return KO;	
        #endif
	}
	else if(fat_type_id == FAT_IS_32)
	{
        #if COMPILE_FAT_32 == TRUE
		if(fat32_get_clusters (chain,  nb_frag) == KO)
			return KO;
        #endif
	}

  	phy_read_close();
  	/* end of file: last fragment must always contain a single cluster */
  	if (chain[fat_last_clust_index].number == 1)
  	{ /* last cluster is the current one */
 //   	fat_last_clust_index = index;
    	chain[fat_last_clust_index].number = 0; /* end of chain marker */
  	}
  	else
  	{ 	
    	chain[fat_last_clust_index ].number--;
		fat_last_clust_index++;  // = index + 1;
    	chain[fat_last_clust_index].cluster.l = chain[fat_last_clust_index - 1].cluster.l + chain[fat_last_clust_index - 1].number;
    	chain[fat_last_clust_index].number = 0; /* end of chain marker */
  	}

  	return OK;
}

/*F**************************************************************************
* NAME: fat_fopen
*----------------------------------------------------------------------------
* PARAMS:
*   mode: READ:   open file for read
*         WRITE:  open file for write
* return:
*   - OK: file opened
*   - KO: file not opened: - file is empty
*                          - low level read error
*----------------------------------------------------------------------------
* PURPOSE:
*   Open the file in read or write mode
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
Byte fat_fopen (Byte mode)
{
  	fat_sector_flag = 0;
  	fat_nb_clust = 0 ;
  	if (mode == FILE_READ)
  	{
    	if (fat_cache.current.size.l == 0)
    	{
      		return KO;                            /* file empty */
    	}
    	else
    	{
      		fat_fchain_nb_clust = 0;              /* start on first contiguous cl */
      		fat_fclust_byte_count = 0;            /* byte 0 of cluster */
      		fat_fchain_index = 0;           /* reset the allocation list variable */
            
      		/* get file allocation list */
      		fat_get_clusters(fclusters, MAX_FILE_FRAGMENT_NUMBER);
  
      		/* seek to the beginning of the file */
      		fat_open_mode = FILE_READ;
		}
  	}
 	return  OK;
}

/*F**************************************************************************
* NAME: fat_fclose
*----------------------------------------------------------------------------
* PURPOSE:
*   Close opened file
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
void fat_fclose (void)
{
    if (fat_open_mode == FILE_READ)
    {
        phy_read_close();                      /* close reading */
    }
    else
    {
    #if COMPILE_FAT_WRITE == TRUE
      	fat_fclust_byte_count=0;
	  	flag_end_disk_file = 0;
        fat_open_mode = FILE_READ;
	 	fat_file_size.l = fat_current_file_size;
	 	if(fat_current_file_size == 0)
	    	return ;
	 	else 
	 	{
		 	if(fat_file_size.l > 0x6400000)
		    	fat_file_size.l = 0x6400000;
	 	}

	 	fat_update_fats(FALSE,&fclusters);            /* Update entry and fat */ 
	 	fat_create_file_name();    
    #endif//COMPILE_FAT_WRITE     
    }
}



/*F**************************************************************************
* NAME: fat_fgetsector
*----------------------------------------------------------------------------
* return:
*   page read
*----------------------------------------------------------------------------
* PURPOSE:
*   Read one page from file
*----------------------------------------------------------------------------
* NOTE:
*   As this function is called very often it must be short and optimized
*   in execution time
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
void fat_fgetsector (void)
{
  	Uint32 sectornum;
  	
  	if((fat_nb_clust % fat_cluster_size) == 0)
  	{
		fat_nb_clust = 0;
		/* extract if necessary the next cluster from the allocation list */
		if ((fclusters[fat_fchain_index].number == fat_fchain_nb_clust)&&(fclusters[0].number != 0))
		{ /* new fragment */
			fat_fchain_index++;
			fat_fchain_nb_clust = 1;
	        //sectornum = fat_ptr_data + ((fclusters[fat_fchain_index].cluster.l) * fat_cluster_size);
			if(fat_type_id == FAT_IS_32)
			{
				sectornum = fat_ptr_data + ((fclusters[fat_fchain_index].cluster.l) * fat_cluster_size);
			}
			else
			{
				sectornum = fat_ptr_data + ((fclusters[fat_fchain_index].cluster.w[0]) * ((Uint32)fat_cluster_size));
			}                                                             /////////w[1]///////////////
			phy_read_open(sectornum);
		}
		else
		{ /* not new fragment */
            if((fat_fchain_index == 0)&&(fat_fchain_nb_clust == 0))
			{
			    //sectornum = fat_ptr_data + (fclusters[fat_fchain_index].cluster.l * fat_cluster_size);
				if(fat_type_id == FAT_IS_32)
				{
					sectornum = fat_ptr_data + ((fclusters[fat_fchain_index].cluster.l) * fat_cluster_size);
				}
				else
				{
					sectornum = fat_ptr_data + ((fclusters[fat_fchain_index].cluster.w[0]) * ((Uint32)fat_cluster_size));
				}                                                            ////////////w[1]////////////////
			  	phy_read_open(sectornum);
			}
			fat_fchain_nb_clust++;                /* one more cluster read */
		}
  	}
  	phy_read_sector();
  	fat_nb_clust ++;
  	fat_fclust_byte_count += fat_sector_size;                  /* one more byte read */     
}


/*F**************************************************************************
* NAME: fat_feof
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*----------------------------------------------------------------------------
* PURPOSE:
*   Return the file end flag
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
Byte fat_feof (void)
{
  	if (fat_fchain_index == fat_last_clust_index)
  	{
    	if (fat_open_mode == FILE_READ)
        	return (fat_fclust_byte_count >= (fat_cache.current.size.l ));
    	else
        	return flag_end_disk_file;
  	}
  	else
  	{	
    	return FALSE;
  	}
}



/*F**************************************************************************
* NAME: fat_fseek_abs
*----------------------------------------------------------------------------
* PARAMS:
*   offset: absolute seek offset in file
*
* return:
*----------------------------------------------------------------------------
* PURPOSE:
*   Move ahead file read pointer of an openned file
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/
void fat_fseek_abs (Uint32 offset)
{
	 Uint16   cluster_offset;                    /* offset size in clusters */
	 Byte    index;

	cluster_offset = offset / (((Uint32)fat_sector_size) * fat_cluster_size);
	index = 0;

	//fat_nb_clust = cluster_offset % fat_cluster_size;
	
	while(cluster_offset > fclusters[index].number)
	{
		cluster_offset -= fclusters[index].number;
		index++;
	}

	/* init file byte counter */
	fat_fclust_byte_count = offset;

	/* set the allocation list variable */
  	fat_fchain_nb_clust = cluster_offset;
	fat_fchain_index = index;
	fat_nb_clust = (offset/fat_sector_size) % fat_cluster_size ;

	if(fat_type_id != FAT_IS_32)
	{
		fclusters[index].cluster.w[0] = 0; //w[1]////////////////////////////////////BIG LITTLE ENDIAN
	}

	phy_read_open(((Uint32)(fclusters[index].cluster.l + cluster_offset) * fat_cluster_size)
                   + (offset / fat_sector_size) % fat_cluster_size + fat_ptr_data);
	
}



/*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:
*****************************************************************************/ 

Byte fat_goto_next (void)
{
  	if(fat_dir_list_index >= (fat_dir_list_last - 1))
      	return KO;
  	fat_dir_list_index++;
  	fat_scan_dir(FALSE);

	//fat_save_file_info(SEARCH_FILE);

    if (fat_dir_seek(((Uint32)fat_dir_all_count) * DIR_SIZE) == OK)
    {
      	fat_get_dir_entry(&fat_cache.current);// update current file info 
      	return OK;
    }
    else
	{
      	return KO;                            // low level error 
	}
}

/*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
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 

Byte fat_goto_prev (void)
{
	Byte min;
  
  	if ((dir_is_root == FALSE)&&((fat_global_id & FILE_DIR) == FILE_DIR))
     	min = 2;
  	else
     	min = 0;

  	if(fat_dir_list_index <= min)
      	return KO;

    fat_dir_list_index--;
	fat_scan_dir(FALSE);

	//fat_save_file_info(SEARCH_FILE);
       
    if (fat_dir_seek(((Uint32)fat_dir_all_count) * DIR_SIZE) == OK)
    { // go to previous file 
      	fat_get_dir_entry(&fat_cache.current);// update current file info 
      	return OK;
    }
    else
      	return KO;                            // low level error 
}

/*F**************************************************************************
* NAME: fat_goto_last
*----------------------------------------------------------------------------
* return:
*   OK: last file available
*   KO: low level error
*----------------------------------------------------------------------------
* PURPOSE:
*   Fetch the last directory info in cache
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 

Byte fat_goto_last (void)
{
  	if(fat_dir_list_last == 0)
      	return KO;

  	fat_dir_list_index = fat_dir_list_last - 1;

  	fat_scan_dir(FALSE);

	//fat_save_file_info(SEARCH_FILE);

  	if (fat_dir_seek(((Uint32)fat_dir_all_count) * DIR_SIZE) == OK)
  	{
    	fat_get_dir_entry(&fat_cache.current);
    	return OK;
  	}
  	else
    	return KO;                              // low level error
}



/*F**************************************************************************
* NAME: fat_goto_first
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*   - OK: first file found
*   - KO: low level error
*----------------------------------------------------------------------------
* PURPOSE:
*   Fetch the first directory info in cache
*----------------------------------------------------------------------------
* REQUIREMENTS:
*****************************************************************************/ 

Byte fat_goto_first (void)
{      
  	if((dir_is_root == FALSE)&&((fat_global_id & FILE_DIR) == FILE_DIR))
  	{ // not root dir 
    	if(fat_dir_list_last <= 2)
			return KO;
    	fat_dir_list_index = 1;                 // point ".." entry
    	if (fat_dir_seek(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
  	{ // root diretory 
    	if(fat_dir_list_last == 0)
	    	return KO;
    	fat_dir_list_index = 0;                 // point first root entry 
		fat_scan_dir(FALSE);
	
	//	fat_save_file_info(SEARCH_FILE);

    	if (fat_dir_seek(((Uint32)fat_dir_all_count) * DIR_SIZE) == OK)
    	{
      		fat_get_dir_entry(&fat_cache.current);// update first file info       
      		return OK;
    	}
    	else
    	{
      		return KO;                            // low level error 
    	}
  	}
}