fs.c

基于lpc2148（arm7）的wav音乐格式播放器的设计

 * Return value: If a free cluster is found it's number is returned. If none is 
 * found 0 is returned.
*/
euint32 fs_getNextFreeCluster(FileSystem *fs,euint32 startingcluster)
{
	euint32 r;
	
	while(startingcluster<fs->DataClusterCount){
		r=fat_getNextClusterAddress(fs,startingcluster,0);
		if(r==0){
			return(startingcluster);
		}
		startingcluster++;
	}
	return(0);
}
/*****************************************************************************/ 

/* ****************************************************************************  
 * euint32 fs_giveFreeClusterHint(FileSystem *fs)
 * 
 * Description: This function should return a clusternumber that is free or
 * lies close before free clusters. The result MUST be checked to see if 
 * it is free! Implementationhint: search the largest clusternumber in the
 * files in the rootdirectory.
 * 
 * Return value: Returns it's best guess.
*/
euint32 fs_giveFreeClusterHint(FileSystem *fs)
{
	return(2); /* Now THIS is a hint ;) */
}
/*****************************************************************************/ 

/* ****************************************************************************
 * esint8 fs_findFile(FileSystem *fs,eint8* filename,FileLocation *loc,euint32 *lastDir)
 *
 * Description: This function looks if the given filename is on the given fs
 * and, if found, fills in its location in loc.
 * The function will first check if the pathname starts with a slash. If so it will
 * set the starting directory to the rootdirectory. Else, it will take the firstcluster-
 * currentdir (That you can change with chdir()) as startingpoint.
 * The lastdir pointer will be the first cluster of the last directory fs_findfile
 * enters. It starts out at the root/current dir and then traverses the path along with
 * fs_findFile. 
 * It is set to 0 in case of errors (like dir/dir/dir/file/dir/dir...)
 * Return value: Returns 0 when nothing was found, 1 when the thing found
 * was a file and 2 if the thing found was a directory.
*/

esint8 fs_findFile(FileSystem *fs, eint8* filename, FileLocation *loc, euint32 *lastDir)
{
	euint32 currentDir, tmpclus;
	eint8 ffname[11], *next, it = 0, filefound = 0;
	
	if(*filename=='/')
	{
		currentDir = fs_getFirstClusterRootDir(fs);
		filename++;
		if(lastDir)*lastDir=currentDir;
		if(!*filename)
		{
			return(2);
		}
	}
	else
	{
		currentDir = fs->FirstClusterCurrentDir;
		if(lastDir)
		{
			*lastDir = currentDir;
		}
	}
	
	
	while((next = file_normalToFatName(filename, ffname)) != 0)
	{
		if((tmpclus = dir_findinDir(fs, ffname, currentDir, loc, DIRFIND_FILE)) == 0)
		{
			/* We didn't find what we wanted */
			/* We should check, to see if there is more after it, so that
			 * we can invalidate lastDir
			 */
			if((file_normalToFatName(next,ffname)) != 0)
			{
				if(lastDir)
				{
					*lastDir=0;
				}
			}			 
			return(0);
		}
		it++;
		if(loc->attrib & ATTR_DIRECTORY)
		{
			currentDir = tmpclus;
			filename = next;
			if(lastDir)
			{
				*lastDir = currentDir;

				/* what in the world is this supposed to do? commenting out - edwards 6/15/2008
				if(filefound)
				{
					*lastDir=0;
				}
				*/
			}
		}
		else
		{
			filefound = 1;
			if((file_normalToFatName(next,ffname)) != 0)
			{
				if(lastDir)
				{
					*lastDir=0;
				}
				return(0);
			}
			else
			{
				filename = next;
			}
		}
	}
	
	if(it == 0)
	{
		return(0);
	}
	
	if(loc->attrib & ATTR_DIRECTORY || !filefound)
	{
		return(2);
	}
	
	return(1);
}
/*****************************************************************************/

esint16 fs_findFreeFile(FileSystem *fs,eint8* filename,FileLocation *loc,euint8 mode)
{
	euint32 targetdir=0;
	eint8 ffname[11];
	
	if(fs_findFile(fs,filename,loc,&targetdir))return(0);
	if(!dir_getFatFileName(filename,ffname))return(0);
	if(dir_findinDir(fs,ffname,targetdir,loc,DIRFIND_FREE)){
		return(1);
	}else{
		if(dir_addCluster(fs,targetdir)){
			return(0);
		}else{
			if(dir_findinDir(fs,ffname,targetdir,loc,DIRFIND_FREE)){
				return(1);
			}
		}
	}
		
	return(0);
}
/*****************************************************************************/

/* ****************************************************************************  
 * euint32 fs_getLastCluster(FileSystem *fs,ClusterChain *Cache)
 * Description: This function searches the last cluster of a chain.
 * Return value: The LastCluster (also stored in cache);
*/
euint32 fs_getLastCluster(FileSystem *fs,ClusterChain *Cache)
{
	if(Cache->DiscCluster==0){
		Cache->DiscCluster=Cache->FirstCluster;
		Cache->LogicCluster=0;
	}
	
	if(Cache->LastCluster==0)
	{
		while(fat_getNextClusterChain(fs, Cache)==0)
		{
			Cache->LogicCluster+=Cache->Linear;
			Cache->DiscCluster+=Cache->Linear;
			Cache->Linear=0;
		}
	}
	return(Cache->LastCluster);
}
/*****************************************************************************/

euint32 fs_getFirstClusterRootDir(FileSystem *fs)
{
	switch(fs->type){
		case FAT32:
			return(fs->volumeId.RootCluster);
			break;
		default:
				return(1);
				break;
	}
}
/*****************************************************************************/

void fs_initClusterChain(FileSystem *fs,ClusterChain *cache,euint32 cluster_addr)
{
	cache->FirstCluster=cluster_addr;
	cache->DiscCluster=cluster_addr;
	cache->LogicCluster=0;
	cache->LastCluster=0; /* Warning flag here */
	cache->Linear=0;
	cache->ClusterCount=0; /* 0 means NOT known */
}
/*****************************************************************************/

void fs_setFirstClusterInDirEntry(FileRecord *rec,euint32 cluster_addr)
{
	rec->FirstClusterHigh=cluster_addr>>16;
	rec->FirstClusterLow=cluster_addr&0xFFFF;
}
/*****************************************************************************/

esint8 fs_flushFs(FileSystem *fs)
{
	return(part_flushPart(fs->part,0,fs->SectorCount));
}
/*****************************************************************************/

esint8 fs_umount(FileSystem *fs)
{
	return(fs_flushFs(fs));
}
/*****************************************************************************/

esint8 fs_clearCluster(FileSystem *fs,euint32 cluster)
{
	euint16 c;
	euint8* buf;
	
	for(c=0;c<(fs->volumeId.SectorsPerCluster);c++){
		buf = part_getSect(fs->part,fs_clusterToSector(fs,cluster)+c,IOM_MODE_READWRITE);
		memClr(buf,512);
		part_relSect(fs->part,buf);
	}
	return(0);
}

esint8 fs_getFsInfo(FileSystem *fs,euint8 force_update)
{
	euint8 *buf;
		
 	if(!fs->type==FAT32)return(0);
	buf = part_getSect(fs->part,FS_INFO_SECTOR,IOM_MODE_READONLY);
	if(ex_getb32(buf,0)!=FSINFO_MAGIC_BEGIN || ex_getb32(buf,508)!=FSINFO_MAGIC_END){
		part_relSect(fs->part,buf);
		return(-1);
	}
	fs->FreeClusterCount = ex_getb32(buf,488);
	fs->NextFreeCluster  = ex_getb32(buf,492);
	part_relSect(fs->part,buf);
	if(force_update){
		fs->FreeClusterCount=fat_countFreeClusters(fs);
	}
	return(0);
}

esint8 fs_setFsInfo(FileSystem *fs)
{
	euint8* buf;

	if(!fs->type==FAT32)return(0);
	buf = part_getSect(fs->part,FS_INFO_SECTOR,IOM_MODE_READWRITE);
	if(ex_getb32(buf,0)!=FSINFO_MAGIC_BEGIN || ex_getb32(buf,508)!=FSINFO_MAGIC_END){
		part_relSect(fs->part,buf);
		return(-1);
	}
	ex_setb32(buf,488,fs->FreeClusterCount);
	ex_setb32(buf,492,fs->NextFreeCluster);
	part_relSect(fs->part,buf);
	return(0);
}