fdefrag.h

嵌入式系统中文件系统源代码

#ifndef _FAT1X_DEFRAG_H
#define _FAT1X_DEFRAG_H


struct defrag_dir {
	
  unsigned short startCluster;
  unsigned short parentCluster;
  unsigned long block;
  unsigned long entry;
  
};

/*************************************************************
Fuction : FAT_defrag
	defrag FAT1x disk
	
	// method
	introduction:
	   1. Record all directories in defragDirList
	   2. Start defragging from root directory. 
	      a) We move all entries upwards by removing all deleted entries
	      b) We defrag root directory entries, sorting every entry from
	      	 cluster number 2.
	   3. Then according to defragDirList, we go through the same
	      steps as we do to root directory. Finally, we update the cluster
	      values of '.' and '..' that might be swapped during defragging
	   4. Because we keep swapping and modifying fat tables from the above
	      three steps, we need to update fat tables by writing the fat buffer
	      back to flash.
	      
	ex: (original)
	   dir/file		clusterNo
	   ---------------------------------
	   \f1.txt		246
	   \f2.txt		247
	   \f3.txt		248
	   \4dos		249
	   \4dos\fat1x.txt	250
	   \4dos\abc		2
	   \4dos\abc\fat1x.txt	3, 4

	ex: (after defragging)
	   dir/file		clusterNo
	   ---------------------------------
	   \f1.txt		2
	   \f2.txt		3
	   \f3.txt		4
	   \4dos		5
	   \4dos\fat1x.txt	6
	   \4dos\abc		7
	   \4dos\abc\fat1x.txt	8, 9
	// method
Input:
Output:
	        0: no error is found
	       -1: error (see FATError)
**************************************************************/
int FAT_defrag(void);

/*************************************************************
Fuction : FAT_set_defragDirList
	Record all the directories in the global variable "defragDirList"
	(from root directory to all its subdirectories sorted in order)
Input:
	drive - drive number
Output:
	        0: no error is found
	       -1: error (see FATError)
**************************************************************/
int FAT_set_defragDirList(short drive);

/*************************************************************
Fuction : FAT_defrag_root
	defrag root directory
Input:
	drive - drive number
Output:
	        0: no error is found
	       -1: error (see FATError)
**************************************************************/
int FAT_defrag_root(short drive);

/*************************************************************
Fuction : FAT_swap_cluster_data
	swap the cluster data
Input:
	drive - drive number
	clusterNo1 - cluster number 1 that's going to be swapped
	clusterNo2 - cluster number 2 that's going to be swapped
Output:
	        0: no error is found
	       -1: error (see FATError)
**************************************************************/
int FAT_swap_cluster_data(short drive, unsigned short clusterNo1, unsigned short clusterNo2);

/*************************************************************
Fuction : FAT_swap_fat_cluster
	swap the cluster value in fat tables and directory entries
Input:
	drive - drive number
	clusterNo1 - cluster number 1 that's going to be swapped
	clusterNo2 - cluster number 2 that's going to be swapped
Output:
	        0: no error is found
	       -1: error (see FATError)
**************************************************************/
int FAT_swap_fat_cluster(short drive, unsigned short clusterNo1, unsigned short clusterNo2);

/*************************************************************
Fuction : FAT_find_entry_location_by_startCluster
	Search the block where startCluster value locates
Input:
	drive - drive number
	startCluster - cluster value that's going to be searched
Output:
        0: no error is found
       -1: error (see FATError)
       
       block: the block number
       entry: the entry in the block
       isRoot: in the root directory?
**************************************************************/
int FAT_find_entry_location_by_startCluster(short drive, unsigned short startCluster, \
	unsigned long *block, unsigned long *entry, int *isRoot);
	
/*************************************************************
Fuction : FAT_free_dirLinkList
	free resources from directory linking list(defragDirList),
	including the memory pointed to by the elementPointer
Input:
	list - the pointer to the linking list
Output:
        0: no error is found
       -1: error (see FATError)
       
**************************************************************/
void FAT_free_dirLinkList(struct dLinkList *list);

/*************************************************************
Fuction : FAT_defrag_subdir
	defrag all subdirectories
Input:
	drive - drive number
Output:
        0: no error is found
       -1: error (see FATError)
**************************************************************/
int FAT_defrag_subdir(short drive);

/*************************************************************
Fuction : FAT_update_clustersInDefragList
	update startCluster and parentCluster in defrag_dir if 
	they are swapped while defragging
Input:
	swapClusterNo1 - cluster number 1 that's going to be swapped with swapClusterNo2
	swapClusterNo2 - cluster number 2 that's going to be swapped with swapClusterNo1
Output:
**************************************************************/
void FAT_update_clustersInDefragList(unsigned short oldClusterNo, unsigned short newClusterNo);

/*************************************************************
Fuction : read_fat_cluster_from_fatBuffer
	read cluster value from fat buffer
Input:
	drive - drive number
	clusterNo - the clusterNo-th entry in fat tables
Output:
	the next cluster value
**************************************************************/
unsigned short read_fat_cluster_from_fatBuffer(short drive, unsigned short clusterNo);

/*************************************************************
Fuction : write_fat_cluster_to_fatBuffer
	write cluster value to fat buffer
Input:
	drive - drive number
	clusterNo - the clusterNo-th entry in fat tables
	cluster - the cluster value that's going to be written
Output:
**************************************************************/
void write_fat_cluster_to_fatBuffer(short drive, unsigned short clusterNo, unsigned short cluster);


#endif