/*++ 
Copyright (c) 2010 WonderMedia Technologies, Inc.

This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software 
Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.  See the GNU General Public License for more details. You
should have received a copy of the GNU General Public License along with this
program. If not, see http://www.gnu.org/licenses/>.

WonderMedia Technologies, Inc.
10F, 529, Chung-Cheng Road, Hsin-Tien, Taipei 231, R.O.C.
--*/
/*
 * fat.c
 *
 * R/O (V)FAT 12/16/32 filesystem implementation by Marcus Sundberg
 *
 * 2002-07-28 - rjones@nexus-tech.net - ported to ppcboot v1.1.6
 * 2003-03-10 - kharris@nexus-tech.net - ported to uboot
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <config.h>
#include <exports.h>
#include <fat.h>
#include <asm/byteorder.h>
#include <part.h>
#include <malloc.h>
#include <linux/compiler.h>

/*
 * Convert a string to lowercase.
 */
static void downcase(char *str)
{
	while (*str != '\0') {
		TOLOWER(*str);
		str++;
	}
}

static block_dev_desc_t *cur_dev;
static unsigned int cur_part_nr;
static disk_partition_t cur_part_info;
static int total_sector;


#define DOS_BOOT_MAGIC_OFFSET	0x1fe
#define DOS_FS_TYPE_OFFSET	0x36
#define DOS_FS32_TYPE_OFFSET	0x52

static int disk_read(__u32 block, __u32 nr_blocks, void *buf)
{
	if (!cur_dev || !cur_dev->block_read)
		return -1;

	return cur_dev->block_read(cur_dev->dev,
			cur_part_info.start + block, nr_blocks, buf);
}




int fatpre_register_device(block_dev_desc_t * dev_desc, int part_no)
{
	/* First close any currently found FAT filesystem */
	cur_dev = NULL;

#if (defined(CONFIG_CMD_IDE) || \
     defined(CONFIG_CMD_SATA) || \
     defined(CONFIG_CMD_SCSI) || \
     defined(CONFIG_CMD_USB) || \
     defined(CONFIG_MMC) || \
     defined(CONFIG_SYSTEMACE) )

	/* Read the partition table, if present */
	if (!get_partition_info(dev_desc, part_no, &cur_part_info)) {
		cur_dev = dev_desc;
		cur_part_nr = part_no;
	}
#endif

	/* Otherwise it might be a superfloppy (whole-disk FAT filesystem) */
	if (!cur_dev) {
		/*if (part_no != 0) {
			printf("** Partition %d not valid on device %d **\n",
					part_no, dev_desc->dev);
			return -1;
		}*/

		cur_dev = dev_desc;
		cur_part_nr = 1;
		cur_part_info.start = 0;
		cur_part_info.size = dev_desc->lba;
		cur_part_info.blksz = dev_desc->blksz;
		memset(cur_part_info.name, 0, sizeof(cur_part_info.name));
		memset(cur_part_info.type, 0, sizeof(cur_part_info.type));
	}
	total_sector = cur_part_info.size;
	return 0;
}

int fat_register_device(block_dev_desc_t * dev_desc, int part_no)
{
	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, dev_desc->blksz);
#if 0
	/* First close any currently found FAT filesystem */
	cur_dev = NULL;

#if (defined(CONFIG_CMD_IDE) || \
     defined(CONFIG_CMD_SATA) || \
     defined(CONFIG_CMD_SCSI) || \
     defined(CONFIG_CMD_USB) || \
     defined(CONFIG_MMC) || \
     defined(CONFIG_SYSTEMACE) )

	/* Read the partition table, if present */
	if (!get_partition_info(dev_desc, part_no, &cur_part_info)) {
		cur_dev = dev_desc;
		cur_part_nr = part_no;
	}
#endif

	/* Otherwise it might be a superfloppy (whole-disk FAT filesystem) */
	if (!cur_dev) {
		if (part_no != 0) {
			printf("** Partition %d not valid on device %d **\n",
					part_no, dev_desc->dev);
			return -1;
		}

		cur_dev = dev_desc;
		cur_part_nr = 1;
		cur_part_info.start = 0;
		cur_part_info.size = dev_desc->lba;
		cur_part_info.blksz = dev_desc->blksz;
		memset(cur_part_info.name, 0, sizeof(cur_part_info.name));
		memset(cur_part_info.type, 0, sizeof(cur_part_info.type));
	}
#endif
	if (fatpre_register_device(dev_desc, part_no))
		return -1;

	/* Make sure it has a valid FAT header */
	if (disk_read(0, 1, buffer) != 1) {
		cur_dev = NULL;
		printf("Cannot read from disk\n");
		return -1;
	}

	/* Check if it's actually a DOS volume */
	if (memcmp(buffer + DOS_BOOT_MAGIC_OFFSET, "\x55\xAA", 2)) {
		printf("It is not a DOS volume\n");
		cur_dev = NULL;
		return -1;
	}

	/* Check for FAT12/FAT16/FAT32 filesystem */
	if (!memcmp(buffer + DOS_FS_TYPE_OFFSET, "FAT", 3))
		return 0;
	if (!memcmp(buffer + DOS_FS32_TYPE_OFFSET, "FAT32", 5))
		return 0;

	printf("The volume cannot be recognized\n");
	cur_dev = NULL;
	return -1;
}

/*
 * Get the first occurence of a directory delimiter ('/' or '\') in a string.
 * Return index into string if found, -1 otherwise.
 */
static int dirdelim(char *str)
{
	char *start = str;

	while (*str != '\0') {
		if (ISDIRDELIM(*str))
			return str - start;
		str++;
	}
	return -1;
}

/*
 * Extract zero terminated short name from a directory entry.
 */
static void get_name(dir_entry *dirent, char *s_name)
{
	char *ptr;

	memcpy(s_name, dirent->name, 8);
	s_name[8] = '\0';
	ptr = s_name;
	while (*ptr && *ptr != ' ')
		ptr++;
	if (dirent->ext[0] && dirent->ext[0] != ' ') {
		*ptr = '.';
		ptr++;
		memcpy(ptr, dirent->ext, 3);
		ptr[3] = '\0';
		while (*ptr && *ptr != ' ')
			ptr++;
	}
	*ptr = '\0';
	if (*s_name == DELETED_FLAG)
		*s_name = '\0';
	else if (*s_name == aRING)
		*s_name = DELETED_FLAG;
	downcase(s_name);
}

/*
 * Get the entry at index 'entry' in a FAT (12/16/32) table.
 * On failure 0x00 is returned.
 */
static __u32 get_fatent(fsdata *mydata, __u32 entry)
{
	__u32 bufnum;
	__u32 off16, offset;
	__u32 ret = 0x00;
	__u16 val1, val2;

	switch (mydata->fatsize) {
	case 32:
		bufnum = entry / FAT32BUFSIZE;
		offset = entry - bufnum * FAT32BUFSIZE;
		break;
	case 16:
		bufnum = entry / FAT16BUFSIZE;
		offset = entry - bufnum * FAT16BUFSIZE;
		break;
	case 12:
		bufnum = entry / FAT12BUFSIZE;
		offset = entry - bufnum * FAT12BUFSIZE;
		break;

	default:
		/* Unsupported FAT size */
		return ret;
	}

	debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
	       mydata->fatsize, entry, entry, offset, offset);

	/* Read a new block of FAT entries into the cache. */
	if (bufnum != mydata->fatbufnum) {
		__u32 getsize = FATBUFBLOCKS;
		__u8 *bufptr = mydata->fatbuf;
		__u32 fatlength = mydata->fatlength;
		__u32 startblock = bufnum * FATBUFBLOCKS;

		if (startblock + getsize > fatlength)
			getsize = fatlength - startblock;

		startblock += mydata->fat_sect;	/* Offset from start of disk */

		if (disk_read(startblock, getsize, bufptr) < 0) {
			debug("Error reading FAT blocks\n");
			return ret;
		}
		mydata->fatbufnum = bufnum;
	}

	/* Get the actual entry from the table */
	switch (mydata->fatsize) {
	case 32:
		ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
		break;
	case 16:
		ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
		break;
	case 12:
		off16 = (offset * 3) / 4;

		switch (offset & 0x3) {
		case 0:
			ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
			ret &= 0xfff;
			break;
		case 1:
			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
			val1 &= 0xf000;
			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
			val2 &= 0x00ff;
			ret = (val2 << 4) | (val1 >> 12);
			break;
		case 2:
			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
			val1 &= 0xff00;
			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
			val2 &= 0x000f;
			ret = (val2 << 8) | (val1 >> 8);
			break;
		case 3:
			ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
			ret = (ret & 0xfff0) >> 4;
			break;
		default:
			break;
		}
		break;
	}
	debug("FAT%d: ret: %08x, offset: %04x\n",
	       mydata->fatsize, ret, offset);

	return ret;
}

/*
 * Read at most 'size' bytes from the specified cluster into 'buffer'.
 * Return 0 on success, -1 otherwise.
 */
static int
get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
{
	__u32 idx = 0;
	__u32 startsect;
	int ret;

	if (clustnum > 0) {
		startsect = mydata->data_begin +
				clustnum * mydata->clust_size;
		if (mydata->fatsize!=32) {//this is for windows format
			if (startsect < mydata->rootdir_sect){
				debug("get_cluster\n");
				startsect=mydata->rootdir_sect;
			}
		}
	} else {
		startsect = mydata->rootdir_sect;
	}

	debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect);

	if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);

		printf("FAT: Misaligned buffer address (%p)\n", buffer);

		while (size >= mydata->sect_size) {
			ret = disk_read(startsect++, 1, tmpbuf);
			if (ret != 1) {
				debug("Error reading data (got %d)\n", ret);
				return -1;
			}

			memcpy(buffer, tmpbuf, mydata->sect_size);
			buffer += mydata->sect_size;
			size -= mydata->sect_size;
		}
	} else {
		idx = size / mydata->sect_size;
		ret = disk_read(startsect, idx, buffer);
		if (ret != idx) {
			debug("Error reading data (got %d)\n", ret);
			return -1;
		}
		startsect += idx;
		idx *= mydata->sect_size;
		buffer += idx;
		size -= idx;
	}
	if (size) {
		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);

		ret = disk_read(startsect, 1, tmpbuf);
		if (ret != 1) {
			debug("Error reading data (got %d)\n", ret);
			return -1;
		}

		memcpy(buffer, tmpbuf, size);
	}

	return 0;
}

/*
 * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr'
 * into 'buffer'.
 * Return the number of bytes read or -1 on fatal errors.
 */
__u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
	__aligned(ARCH_DMA_MINALIGN);

static long
get_contents(fsdata *mydata, dir_entry *dentptr, unsigned long pos,
	     __u8 *buffer, unsigned long maxsize)
{
	unsigned long filesize = FAT2CPU32(dentptr->size), gotsize = 0;
	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
	__u32 curclust = START(dentptr);
	__u32 endclust, newclust;
	unsigned long actsize;

	debug("Filesize: %ld bytes\n", filesize);

	if (pos >= filesize) {
		debug("Read position past EOF: %lu\n", pos);
		return gotsize;
	}

	if (maxsize > 0 && filesize > pos + maxsize)
		filesize = pos + maxsize;

	debug("%ld bytes\n", filesize);

	actsize = bytesperclust;

	/* go to cluster at pos */
	while (actsize <= pos) {
		curclust = get_fatent(mydata, curclust);
		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			debug("Invalid FAT entry\n");
			return gotsize;
		}
		actsize += bytesperclust;
	}

	/* actsize > pos */
	actsize -= bytesperclust;
	filesize -= actsize;
	pos -= actsize;

	/* align to beginning of next cluster if any */
	if (pos) {
		actsize = min(filesize, bytesperclust);
		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
				(int)actsize) != 0) {
			printf("Error reading cluster\n");
			return -1;
		}
		filesize -= actsize;
		actsize -= pos;
		memcpy(buffer, get_contents_vfatname_block + pos, actsize);
		gotsize += actsize;
		if (!filesize)
			return gotsize;
		buffer += actsize;

		curclust = get_fatent(mydata, curclust);
		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			debug("Invalid FAT entry\n");
			return gotsize;
		}
	}

	actsize = bytesperclust;
	endclust = curclust;

	do {
		/* search for consecutive clusters */
		while (actsize < filesize) {
			newclust = get_fatent(mydata, endclust);
			if ((newclust - 1) != endclust)
				goto getit;
			if (CHECK_CLUST(newclust, mydata->fatsize)) {
				debug("curclust: 0x%x\n", newclust);
				debug("Invalid FAT entry\n");
				return gotsize;
			}
			endclust = newclust;
			actsize += bytesperclust;
		}

		/* get remaining bytes */
		actsize = filesize;
		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
			printf("Error reading cluster\n");
			return -1;
		}
		gotsize += actsize;
		return gotsize;
getit:
		if (get_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
			printf("Error reading cluster\n");
			return -1;
		}
		gotsize += (int)actsize;
		filesize -= actsize;
		buffer += actsize;

		curclust = get_fatent(mydata, endclust);
		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			printf("Invalid FAT entry\n");
			return gotsize;
		}
		actsize = bytesperclust;
		endclust = curclust;
	} while (1);
}

#ifdef CONFIG_SUPPORT_VFAT
/*
 * Extract the file name information from 'slotptr' into 'l_name',
 * starting at l_name[*idx].
 * Return 1 if terminator (zero byte) is found, 0 otherwise.
 */
static int slot2str(dir_slot *slotptr, char *l_name, int *idx)
{
	int j;

	for (j = 0; j <= 8; j += 2) {
		l_name[*idx] = slotptr->name0_4[j];
		if (l_name[*idx] == 0x00)
			return 1;
		(*idx)++;
	}
	for (j = 0; j <= 10; j += 2) {
		l_name[*idx] = slotptr->name5_10[j];
		if (l_name[*idx] == 0x00)
			return 1;
		(*idx)++;
	}
	for (j = 0; j <= 2; j += 2) {
		l_name[*idx] = slotptr->name11_12[j];
		if (l_name[*idx] == 0x00)
			return 1;
		(*idx)++;
	}

	return 0;
}

/*
 * Extract the full long filename starting at 'retdent' (which is really
 * a slot) into 'l_name'. If successful also copy the real directory entry
 * into 'retdent'
 * Return 0 on success, -1 otherwise.
 */
static int
get_vfatname(fsdata *mydata, int curclust, __u8 *cluster,
	     dir_entry *retdent, char *l_name)
{
	dir_entry *realdent;
	dir_slot *slotptr = (dir_slot *)retdent;
	__u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
							PREFETCH_BLOCKS :
							mydata->clust_size);
	__u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
	int idx = 0;

	if (counter > VFAT_MAXSEQ) {
		debug("Error: VFAT name is too long\n");
		return -1;
	}

	while ((__u8 *)slotptr < buflimit) {
		if (counter == 0)
			break;
		if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
			return -1;
		slotptr++;
		counter--;
	}

	if ((__u8 *)slotptr >= buflimit) {
		dir_slot *slotptr2;

		if (curclust == 0)
			return -1;
		curclust = get_fatent(mydata, curclust);
		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			printf("Invalid FAT entry\n");
			return -1;
		}

		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
				mydata->clust_size * mydata->sect_size) != 0) {
			debug("Error: reading directory block\n");
			return -1;
		}

		slotptr2 = (dir_slot *)get_contents_vfatname_block;
		while (counter > 0) {
			if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
			    & 0xff) != counter)
				return -1;
			slotptr2++;
			counter--;
		}

		/* Save the real directory entry */
		realdent = (dir_entry *)slotptr2;
		while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
			slotptr2--;
			slot2str(slotptr2, l_name, &idx);
		}
	} else {
		/* Save the real directory entry */
		realdent = (dir_entry *)slotptr;
	}

	do {
		slotptr--;
		if (slot2str(slotptr, l_name, &idx))
			break;
	} while (!(slotptr->id & LAST_LONG_ENTRY_MASK));

	l_name[idx] = '\0';
	if (*l_name == DELETED_FLAG)
		*l_name = '\0';
	else if (*l_name == aRING)
		*l_name = DELETED_FLAG;
	downcase(l_name);

	/* Return the real directory entry */
	memcpy(retdent, realdent, sizeof(dir_entry));

	return 0;
}

/* Calculate short name checksum */
static __u8 mkcksum(const char *str)
{
	int i;

	__u8 ret = 0;

	for (i = 0; i < 11; i++) {
		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + str[i];
	}

	return ret;
}
#endif	/* CONFIG_SUPPORT_VFAT */

/*
 * Get the directory entry associated with 'filename' from the directory
 * starting at 'startsect'
 */
__u8 get_dentfromdir_block[MAX_CLUSTSIZE]
	__aligned(ARCH_DMA_MINALIGN);
char fat_fwc[260];

static dir_entry *get_dentfromdir(fsdata *mydata, int startsect,
				  char *filename, dir_entry *retdent,
				  int dols)
{
	__u16 prevcksum = 0xffff;
	__u32 curclust = START(retdent);
	int files = 0, dirs = 0;

	debug("get_dentfromdir: %s\n", filename);

	while (1) {
		dir_entry *dentptr;

		int i;

		if (get_cluster(mydata, curclust, get_dentfromdir_block,
				mydata->clust_size * mydata->sect_size) != 0) {
			debug("Error: reading directory block\n");
			return NULL;
		}

		dentptr = (dir_entry *)get_dentfromdir_block;

		for (i = 0; i < DIRENTSPERCLUST; i++) {
			char s_name[14], l_name[VFAT_MAXLEN_BYTES];

			l_name[0] = '\0';
			if (dentptr->name[0] == DELETED_FLAG) {
				dentptr++;
				continue;
			}
			if ((dentptr->attr & ATTR_VOLUME)) {
#ifdef CONFIG_SUPPORT_VFAT
				if ((dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
					prevcksum = ((dir_slot *)dentptr)->alias_checksum;
					get_vfatname(mydata, curclust,
						     get_dentfromdir_block,
						     dentptr, l_name);
					if (dols) {
						int isdir;
						char dirc;
						int doit = 0;

						isdir = (dentptr->attr & ATTR_DIR);

						if (isdir) {
							dirs++;
							dirc = '/';
							doit = 1;
						} else {
							dirc = ' ';
							if (l_name[0] != 0) {
								files++;
								doit = 1;
							}
						}
						if (doit) {
							if (dirc == ' ') {
								printf(" %8ld   %s%c\n",
									(long)FAT2CPU32(dentptr->size),
									l_name,
									dirc);
								if ((l_name[0] == '+') && (strstr(l_name, ".fwc") > 0)) {
									strcpy(fat_fwc, l_name);
								}
							} else {
								printf("            %s%c\n",
									l_name,
									dirc);
							}
						}
						dentptr++;
						continue;
					}
					debug("vfatname: |%s|\n", l_name);
				} else
#endif
				{
					/* Volume label or VFAT entry */
					dentptr++;
					continue;
				}
			}
			if (dentptr->name[0] == 0) {
				if (dols) {
					printf("\n%d file(s), %d dir(s)\n\n",
						files, dirs);
				}
				debug("Dentname == NULL - %d\n", i);
				return NULL;
			}
#ifdef CONFIG_SUPPORT_VFAT
			if (dols && mkcksum(dentptr->name) == prevcksum) {
				prevcksum = 0xffff;
				dentptr++;
				continue;
			}
#endif
			get_name(dentptr, s_name);
			if (dols) {
				int isdir = (dentptr->attr & ATTR_DIR);
				char dirc;
				int doit = 0;

				if (isdir) {
					dirs++;
					dirc = '/';
					doit = 1;
				} else {
					dirc = ' ';
					if (s_name[0] != 0) {
						files++;
						doit = 1;
					}
				}

				if (doit) {
					if (dirc == ' ') {
						printf(" %8ld   %s%c\n",
							(long)FAT2CPU32(dentptr->size),
							s_name, dirc);
					} else {
						printf("            %s%c\n",
							s_name, dirc);
					}
				}

				dentptr++;
				continue;
			}

			if (strcmp(filename, s_name)
			    && strcmp(filename, l_name)) {
				debug("Mismatch: |%s|%s|\n", s_name, l_name);
				dentptr++;
				continue;
			}

			memcpy(retdent, dentptr, sizeof(dir_entry));

			debug("DentName: %s", s_name);
			debug(", start: 0x%x", START(dentptr));
			debug(", size:  0x%x %s\n",
			      FAT2CPU32(dentptr->size),
			      (dentptr->attr & ATTR_DIR) ? "(DIR)" : "");

			return retdent;
		}

		curclust = get_fatent(mydata, curclust);
		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			printf("Invalid FAT entry\n");
			return NULL;
		}
	}

	return NULL;
}

/*
 * Read boot sector and volume info from a FAT filesystem
 */
static int
read_bootsectandvi(boot_sector *bs, volume_info *volinfo, int *fatsize)
{
	__u8 *block;
	volume_info *vistart;
	int ret = 0;

	if (cur_dev == NULL) {
		debug("Error: no device selected\n");
		return -1;
	}

	block = memalign(ARCH_DMA_MINALIGN, cur_dev->blksz);
	if (block == NULL) {
		debug("Error: allocating block\n");
		return -1;
	}

	if (disk_read(0, 1, block) < 0) {
		debug("Error: reading block\n");
		goto fail;
	}

	memcpy(bs, block, sizeof(boot_sector));
	bs->reserved = FAT2CPU16(bs->reserved);
	bs->fat_length = FAT2CPU16(bs->fat_length);
	bs->secs_track = FAT2CPU16(bs->secs_track);
	bs->heads = FAT2CPU16(bs->heads);
	bs->total_sect = FAT2CPU32(bs->total_sect);

	/* FAT32 entries */
	if (bs->fat_length == 0) {
		/* Assume FAT32 */
		bs->fat32_length = FAT2CPU32(bs->fat32_length);
		bs->flags = FAT2CPU16(bs->flags);
		bs->root_cluster = FAT2CPU32(bs->root_cluster);
		bs->info_sector = FAT2CPU16(bs->info_sector);
		bs->backup_boot = FAT2CPU16(bs->backup_boot);
		vistart = (volume_info *)(block + sizeof(boot_sector));
		*fatsize = 32;
	} else {
		vistart = (volume_info *)&(bs->fat32_length);
		*fatsize = 0;
	}
	memcpy(volinfo, vistart, sizeof(volume_info));

	if (*fatsize == 32) {
		if (strncmp(FAT32_SIGN, vistart->fs_type, SIGNLEN) == 0)
			goto exit;
	} else {
		if (strncmp(FAT12_SIGN, vistart->fs_type, SIGNLEN) == 0) {
			*fatsize = 12;
			goto exit;
		}
		if (strncmp(FAT16_SIGN, vistart->fs_type, SIGNLEN) == 0) {
			*fatsize = 16;
			goto exit;
		}
	}

	debug("Error: broken fs_type sign\n");
fail:
	ret = -1;
exit:
	free(block);
	return ret;
}

__u8 do_fat_read_at_block[MAX_CLUSTSIZE]
	__aligned(ARCH_DMA_MINALIGN);

long
do_fat_read_at(const char *filename, unsigned long pos, void *buffer,
	       unsigned long maxsize, int dols)
{
	char fnamecopy[2048];
	boot_sector bs;
	volume_info volinfo;
	fsdata datablock;
	fsdata *mydata = &datablock;
	dir_entry *dentptr = NULL;
	__u16 prevcksum = 0xffff;
	char *subname = "";
	__u32 cursect;
	int idx, isdir = 0;
	int files = 0, dirs = 0;
	long ret = -1;
	int firsttime;
	__u32 root_cluster = 0;
	int rootdir_size = 0;
	int j;

	if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
		debug("Error: reading boot sector\n");
		return -1;
	}

	if (mydata->fatsize == 32) {
		root_cluster = bs.root_cluster;
		mydata->fatlength = bs.fat32_length;
	} else {
		mydata->fatlength = bs.fat_length;
	}

	mydata->fat_sect = bs.reserved;

	cursect = mydata->rootdir_sect
		= mydata->fat_sect + mydata->fatlength * bs.fats;

	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
	mydata->clust_size = bs.cluster_size;
	if (mydata->sect_size != cur_part_info.blksz) {
		printf("Error: FAT sector size mismatch (fs=%hu, dev=%lu)\n",
				mydata->sect_size, cur_part_info.blksz);
		return -1;
	}

	if (mydata->fatsize == 32) {
		mydata->data_begin = mydata->rootdir_sect -
					(mydata->clust_size * 2);
	} else {
		rootdir_size = ((bs.dir_entries[1]  * (int)256 +
				 bs.dir_entries[0]) *
				 sizeof(dir_entry)) /
				 mydata->sect_size;
		mydata->data_begin = mydata->rootdir_sect +
					rootdir_size -
					(mydata->clust_size * 2);
	}

	mydata->fatbufnum = -1;
	mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
	if (mydata->fatbuf == NULL) {
		debug("Error: allocating memory\n");
		return -1;
	}

#ifdef CONFIG_SUPPORT_VFAT
	debug("VFAT Support enabled\n");
#endif
	debug("FAT%d, fat_sect: %d, fatlength: %d\n",
	       mydata->fatsize, mydata->fat_sect, mydata->fatlength);
	debug("Rootdir begins at cluster: %d, sector: %d, offset: %x\n"
	       "Data begins at: %d\n",
	       root_cluster,
	       mydata->rootdir_sect,
	       mydata->rootdir_sect * mydata->sect_size, mydata->data_begin);
	debug("Sector size: %d, cluster size: %d\n", mydata->sect_size,
	      mydata->clust_size);

	/* "cwd" is always the root... */
	while (ISDIRDELIM(*filename))
		filename++;

	/* Make a copy of the filename and convert it to lowercase */
	strcpy(fnamecopy, filename);
	downcase(fnamecopy);

	if (*fnamecopy == '\0') {
		if (!dols)
			goto exit;

		dols = LS_ROOT;
	} else if ((idx = dirdelim(fnamecopy)) >= 0) {
		isdir = 1;
		fnamecopy[idx] = '\0';
		subname = fnamecopy + idx + 1;

		/* Handle multiple delimiters */
		while (ISDIRDELIM(*subname))
			subname++;
	} else if (dols) {
		isdir = 1;
	}

	j = 0;
	while (1) {
		int i;

		if (j == 0) {
			debug("FAT read sect=%d, clust_size=%d, DIRENTSPERBLOCK=%zd\n",
				cursect, mydata->clust_size, DIRENTSPERBLOCK);

			if (disk_read(cursect,
					(mydata->fatsize == 32) ?
					(mydata->clust_size) :
					PREFETCH_BLOCKS,
					do_fat_read_at_block) < 0) {
				debug("Error: reading rootdir block\n");
				goto exit;
			}

			dentptr = (dir_entry *) do_fat_read_at_block;
		}

		for (i = 0; i < DIRENTSPERBLOCK; i++) {
			char s_name[14], l_name[VFAT_MAXLEN_BYTES];

			l_name[0] = '\0';
			if (dentptr->name[0] == DELETED_FLAG) {
				dentptr++;
				continue;
			}
			if ((dentptr->attr & ATTR_VOLUME)) {
#ifdef CONFIG_SUPPORT_VFAT
				if ((dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
					prevcksum =
						((dir_slot *)dentptr)->alias_checksum;

					get_vfatname(mydata,
						     root_cluster,
						     do_fat_read_at_block,
						     dentptr, l_name);

					if (dols == LS_ROOT) {
						char dirc;
						int doit = 0;
						int isdir =
							(dentptr->attr & ATTR_DIR);

						if (isdir) {
							dirs++;
							dirc = '/';
							doit = 1;
						} else {
							dirc = ' ';
							if (l_name[0] != 0) {
								files++;
								doit = 1;
							}
						}
						if (doit) {
							if (dirc == ' ') {
								printf(" %8ld   %s%c\n",
									(long)FAT2CPU32(dentptr->size),
									l_name,
									dirc);
							} else {
								printf("            %s%c\n",
									l_name,
									dirc);
							}
						}
						dentptr++;
						continue;
					}
					debug("Rootvfatname: |%s|\n",
					       l_name);
				} else
#endif
				{
					/* Volume label or VFAT entry */
					dentptr++;
					continue;
				}
			} else if (dentptr->name[0] == 0) {
				debug("RootDentname == NULL - %d\n", i);
				if (dols == LS_ROOT) {
					printf("\n%d file(s), %d dir(s)\n\n",
						files, dirs);
					ret = 0;
				}
				goto exit;
			}
#ifdef CONFIG_SUPPORT_VFAT
			else if (dols == LS_ROOT &&
				 mkcksum(dentptr->name) == prevcksum) {
				prevcksum = 0xffff;
				dentptr++;
				continue;
			}
#endif
			get_name(dentptr, s_name);

			if (dols == LS_ROOT) {
				int isdir = (dentptr->attr & ATTR_DIR);
				char dirc;
				int doit = 0;

				if (isdir) {
					dirc = '/';
					if (s_name[0] != 0) {
						dirs++;
						doit = 1;
					}
				} else {
					dirc = ' ';
					if (s_name[0] != 0) {
						files++;
						doit = 1;
					}
				}
				if (doit) {
					if (dirc == ' ') {
						printf(" %8ld   %s%c\n",
							(long)FAT2CPU32(dentptr->size),
							s_name, dirc);
					} else {
						printf("            %s%c\n",
							s_name, dirc);
					}
				}
				dentptr++;
				continue;
			}

			if (strcmp(fnamecopy, s_name)
			    && strcmp(fnamecopy, l_name)) {
				debug("RootMismatch: |%s|%s|\n", s_name,
				       l_name);
				dentptr++;
				continue;
			}

			if (isdir && !(dentptr->attr & ATTR_DIR))
				goto exit;

			debug("RootName: %s", s_name);
			debug(", start: 0x%x", START(dentptr));
			debug(", size:  0x%x %s\n",
			       FAT2CPU32(dentptr->size),
			       isdir ? "(DIR)" : "");

			goto rootdir_done;	/* We got a match */
		}
		debug("END LOOP: j=%d   clust_size=%d\n", j,
		       mydata->clust_size);

		/*
		 * On FAT32 we must fetch the FAT entries for the next
		 * root directory clusters when a cluster has been
		 * completely processed.
		 */
		++j;
		int rootdir_end = 0;
		if (mydata->fatsize == 32) {
			if (j == mydata->clust_size) {
				int nxtsect = 0;
				int nxt_clust = 0;

				nxt_clust = get_fatent(mydata, root_cluster);
				rootdir_end = CHECK_CLUST(nxt_clust, 32);

				nxtsect = mydata->data_begin +
					(nxt_clust * mydata->clust_size);

				root_cluster = nxt_clust;

				cursect = nxtsect;
				j = 0;
			}
		} else {
			if (j == PREFETCH_BLOCKS)
				j = 0;

			rootdir_end = (++cursect - mydata->rootdir_sect >=
				       rootdir_size);
		}

		/* If end of rootdir reached */
		if (rootdir_end) {
			if (dols == LS_ROOT) {
				printf("\n%d file(s), %d dir(s)\n\n",
				       files, dirs);
				ret = 0;
			}
			goto exit;
		}
	}
rootdir_done:

	firsttime = 1;

	while (isdir) {
		int startsect = mydata->data_begin
			+ START(dentptr) * mydata->clust_size;
		dir_entry dent;
		char *nextname = NULL;

		dent = *dentptr;
		dentptr = &dent;

		idx = dirdelim(subname);

		if (idx >= 0) {
			subname[idx] = '\0';
			nextname = subname + idx + 1;
			/* Handle multiple delimiters */
			while (ISDIRDELIM(*nextname))
				nextname++;
			if (dols && *nextname == '\0')
				firsttime = 0;
		} else {
			if (dols && firsttime) {
				firsttime = 0;
			} else {
				isdir = 0;
			}
		}

		if (get_dentfromdir(mydata, startsect, subname, dentptr,
				     isdir ? 0 : dols) == NULL) {
			if (dols && !isdir)
				ret = 0;
			goto exit;
		}

		if (isdir && !(dentptr->attr & ATTR_DIR))
			goto exit;

		if (idx >= 0)
			subname = nextname;
	}

	ret = get_contents(mydata, dentptr, pos, buffer, maxsize);
	debug("Size: %d, got: %ld\n", FAT2CPU32(dentptr->size), ret);

exit:
	free(mydata->fatbuf);
	return ret;
}

long
do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols)
{
	return do_fat_read_at(filename, 0, buffer, maxsize, dols);
}

int file_fat_detectfs(void)
{
	boot_sector bs;
	volume_info volinfo;
	int fatsize;
	char vol_label[12];

	if (cur_dev == NULL) {
		printf("No current device\n");
		return 1;
	}

#if defined(CONFIG_CMD_IDE) || \
    defined(CONFIG_CMD_SATA) || \
    defined(CONFIG_CMD_SCSI) || \
    defined(CONFIG_CMD_USB) || \
    defined(CONFIG_MMC)
	printf("Interface:  ");
	switch (cur_dev->if_type) {
	case IF_TYPE_IDE:
		printf("IDE");
		break;
	case IF_TYPE_SATA:
		printf("SATA");
		break;
	case IF_TYPE_SCSI:
		printf("SCSI");
		break;
	case IF_TYPE_ATAPI:
		printf("ATAPI");
		break;
	case IF_TYPE_USB:
		printf("USB");
		break;
	case IF_TYPE_DOC:
		printf("DOC");
		break;
	case IF_TYPE_MMC:
		printf("MMC");
		break;
	default:
		printf("Unknown");
	}

	printf("\n  Device %d: ", cur_dev->dev);
	dev_print(cur_dev);
#endif

	if (read_bootsectandvi(&bs, &volinfo, &fatsize)) {
		printf("\nNo valid FAT fs found\n");
		return 1;
	}

	memcpy(vol_label, volinfo.volume_label, 11);
	vol_label[11] = '\0';
	volinfo.fs_type[5] = '\0';

	printf("Partition %d: Filesystem: %s \"%s\"\n", cur_part_nr,
		volinfo.fs_type, vol_label);

	return 0;
}

int file_fat_ls(const char *dir)
{
	return do_fat_read(dir, NULL, 0, LS_YES);
}

long file_fat_read_at(const char *filename, unsigned long pos, void *buffer,
		      unsigned long maxsize)
{
	printf("reading %s\n", filename);
	return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO);
}

long file_fat_read(const char *filename, void *buffer, unsigned long maxsize)
{
	return file_fat_read_at(filename, 0, buffer, maxsize);
}

static void uppercase(char *str, int len)
{
	int i;

	for (i = 0; i < len; i++) {
		TOUPPER(*str);
		str++;
	}
}

static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
{
	if (!cur_dev || !cur_dev->block_write)
		return -1;

	if (cur_part_info.start + block + nr_blocks >
		cur_part_info.start + total_sector) {
		printf("error: overflow occurs\n");
		return -1;
	}

	return cur_dev->block_write(cur_dev->dev,
			cur_part_info.start + block, nr_blocks,	buf);
}

/*
 * Set short name in directory entry
 */
static void set_name(dir_entry *dirent, const char *filename)
{
	char s_name[VFAT_MAXLEN_BYTES];
	char *period;
	int period_location, len, i, ext_num;

	if (filename == NULL)
		return;

	len = strlen(filename);
	if (len == 0)
		return;

	memcpy(s_name, filename, len);
	uppercase(s_name, len);

	period = strchr(s_name, '.');
	if (period == NULL) {
		period_location = len;
		ext_num = 0;
	} else {
		period_location = period - s_name;
		ext_num = len - period_location - 1;
	}

	/* Pad spaces when the length of file name is shorter than eight */
	if (period_location < 8) {
		memcpy(dirent->name, s_name, period_location);
		for (i = period_location; i < 8; i++)
			dirent->name[i] = ' ';
	} else if (period_location == 8) {
		memcpy(dirent->name, s_name, period_location);
	} else {
		memcpy(dirent->name, s_name, 6);
		dirent->name[6] = '~';
		dirent->name[7] = '1';
	}

	if (ext_num < 3) {
		memcpy(dirent->ext, s_name + period_location + 1, ext_num);
		for (i = ext_num; i < 3; i++)
			dirent->ext[i] = ' ';
	} else
		memcpy(dirent->ext, s_name + period_location + 1, 3);

	debug("name : %s\n", dirent->name);
	debug("ext : %s\n", dirent->ext);
}

static __u8 num_of_fats;
/*
 * Write fat buffer into block device
 */
static int flush_fat_buffer(fsdata *mydata)
{
	int getsize = FATBUFBLOCKS;
	__u32 fatlength = mydata->fatlength;
	__u8 *bufptr = mydata->fatbuf;
	__u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;

	fatlength *= mydata->sect_size;
	startblock += mydata->fat_sect;

	if (getsize > fatlength)
		getsize = fatlength;

	/* Write FAT buf */
	if (disk_write(startblock, getsize, bufptr) < 0) {
		debug("error: writing FAT blocks\n");
		return -1;
	}

	if (num_of_fats == 2) {
		/* Update corresponding second FAT blocks */
		startblock += mydata->fatlength;
		if (disk_write(startblock, getsize, bufptr) < 0) {
			debug("error: writing second FAT blocks\n");
			return -1;
		}
	}

	return 0;
}

/*
 * Get the entry at index 'entry' in a FAT (12/16/32) table.
 * On failure 0x00 is returned.
 * When bufnum is changed, write back the previous fatbuf to the disk.
 */
static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
{
	__u32 bufnum;
	__u32 off16, offset;
	__u32 ret = 0x00;
	__u16 val1, val2;

	switch (mydata->fatsize) {
	case 32:
		bufnum = entry / FAT32BUFSIZE;
		offset = entry - bufnum * FAT32BUFSIZE;
		break;
	case 16:
		bufnum = entry / FAT16BUFSIZE;
		offset = entry - bufnum * FAT16BUFSIZE;
		break;
	case 12:
		bufnum = entry / FAT12BUFSIZE;
		offset = entry - bufnum * FAT12BUFSIZE;
		break;

	default:
		/* Unsupported FAT size */
		return ret;
	}

	debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
	       mydata->fatsize, entry, entry, offset, offset);

	/* Read a new block of FAT entries into the cache. */
	if (bufnum != mydata->fatbufnum) {
		int getsize = FATBUFBLOCKS;
		__u8 *bufptr = mydata->fatbuf;
		__u32 fatlength = mydata->fatlength;
		__u32 startblock = bufnum * FATBUFBLOCKS;

		if (getsize > fatlength)
			getsize = fatlength;

		fatlength *= mydata->sect_size;	/* We want it in bytes now */
		startblock += mydata->fat_sect;	/* Offset from start of disk */

		/* Write back the fatbuf to the disk */
		if (mydata->fatbufnum != -1) {
			if (flush_fat_buffer(mydata) < 0)
				return -1;
		}

		if (disk_read(startblock, getsize, bufptr) < 0) {
			debug("Error reading FAT blocks\n");
			return ret;
		}
		mydata->fatbufnum = bufnum;
	}

	/* Get the actual entry from the table */
	switch (mydata->fatsize) {
	case 32:
		ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
		break;
	case 16:
		ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
		break;
	case 12:
		off16 = (offset * 3) / 4;

		switch (offset & 0x3) {
		case 0:
			ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
			ret &= 0xfff;
			break;
		case 1:
			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
			val1 &= 0xf000;
			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
			val2 &= 0x00ff;
			ret = (val2 << 4) | (val1 >> 12);
			break;
		case 2:
			val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
			val1 &= 0xff00;
			val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
			val2 &= 0x000f;
			ret = (val2 << 8) | (val1 >> 8);
			break;
		case 3:
			ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
			ret = (ret & 0xfff0) >> 4;
			break;
		default:
			break;
		}
		break;
	}
	debug("FAT%d: ret: %08x, entry: %08x, offset: %04x\n",
	       mydata->fatsize, ret, entry, offset);

	return ret;
}

#ifdef CONFIG_SUPPORT_VFAT
/*
 * Set the file name information from 'name' into 'slotptr',
 */
static int str2slot(dir_slot *slotptr, const char *name, int *idx)
{
	int j, end_idx = 0;

	for (j = 0; j <= 8; j += 2) {
		if (name[*idx] == 0x00) {
			slotptr->name0_4[j] = 0;
			slotptr->name0_4[j + 1] = 0;
			end_idx++;
			goto name0_4;
		}
		slotptr->name0_4[j] = name[*idx];
		(*idx)++;
		end_idx++;
	}
	for (j = 0; j <= 10; j += 2) {
		if (name[*idx] == 0x00) {
			slotptr->name5_10[j] = 0;
			slotptr->name5_10[j + 1] = 0;
			end_idx++;
			goto name5_10;
		}
		slotptr->name5_10[j] = name[*idx];
		(*idx)++;
		end_idx++;
	}
	for (j = 0; j <= 2; j += 2) {
		if (name[*idx] == 0x00) {
			slotptr->name11_12[j] = 0;
			slotptr->name11_12[j + 1] = 0;
			end_idx++;
			goto name11_12;
		}
		slotptr->name11_12[j] = name[*idx];
		(*idx)++;
		end_idx++;
	}

	if (name[*idx] == 0x00)
		return 1;

	return 0;
/* Not used characters are filled with 0xff 0xff */
name0_4:
	for (; end_idx < 5; end_idx++) {
		slotptr->name0_4[end_idx * 2] = 0xff;
		slotptr->name0_4[end_idx * 2 + 1] = 0xff;
	}
	end_idx = 5;
name5_10:
	end_idx -= 5;
	for (; end_idx < 6; end_idx++) {
		slotptr->name5_10[end_idx * 2] = 0xff;
		slotptr->name5_10[end_idx * 2 + 1] = 0xff;
	}
	end_idx = 11;
name11_12:
	end_idx -= 11;
	for (; end_idx < 2; end_idx++) {
		slotptr->name11_12[end_idx * 2] = 0xff;
		slotptr->name11_12[end_idx * 2 + 1] = 0xff;
	}

	return 1;
}

static int is_next_clust(fsdata *mydata, dir_entry *dentptr);
static void flush_dir_table(fsdata *mydata, dir_entry **dentptr);

/*
 * Fill dir_slot entries with appropriate name, id, and attr
 * The real directory entry is returned by 'dentptr'
 */
static void
fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
{
	dir_slot *slotptr = (dir_slot *)get_contents_vfatname_block;
	__u8 counter = 0, checksum;
	int idx = 0, ret;
	char s_name[16];

	/* Get short file name and checksum value */
	strncpy(s_name, (*dentptr)->name, 16);
	checksum = mkcksum(s_name);

	do {
		memset(slotptr, 0x00, sizeof(dir_slot));
		ret = str2slot(slotptr, l_name, &idx);
		slotptr->id = ++counter;
		slotptr->attr = ATTR_VFAT;
		slotptr->alias_checksum = checksum;
		slotptr++;
	} while (ret == 0);

	slotptr--;
	slotptr->id |= LAST_LONG_ENTRY_MASK;

	while (counter >= 1) {
		if (is_next_clust(mydata, *dentptr)) {
			/* A new cluster is allocated for directory table */
			flush_dir_table(mydata, dentptr);
		}
		memcpy(*dentptr, slotptr, sizeof(dir_slot));
		(*dentptr)++;
		slotptr--;
		counter--;
	}

	if (is_next_clust(mydata, *dentptr)) {
		/* A new cluster is allocated for directory table */
		flush_dir_table(mydata, dentptr);
	}
}

static __u32 dir_curclust;

/*
 * Extract the full long filename starting at 'retdent' (which is really
 * a slot) into 'l_name'. If successful also copy the real directory entry
 * into 'retdent'
 * If additional adjacent cluster for directory entries is read into memory,
 * then 'get_contents_vfatname_block' is copied into 'get_dentfromdir_block' and
 * the location of the real directory entry is returned by 'retdent'
 * Return 0 on success, -1 otherwise.
 */
static int
get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster,
	      dir_entry **retdent, char *l_name)
{
	dir_entry *realdent;
	dir_slot *slotptr = (dir_slot *)(*retdent);
	dir_slot *slotptr2 = NULL;
	__u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
							PREFETCH_BLOCKS :
							mydata->clust_size);
	__u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
	int idx = 0, cur_position = 0;

	if (counter > VFAT_MAXSEQ) {
		debug("Error: VFAT name is too long\n");
		return -1;
	}

	while ((__u8 *)slotptr < buflimit) {
		if (counter == 0)
			break;
		if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
			return -1;
		slotptr++;
		counter--;
	}

	if ((__u8 *)slotptr >= buflimit) {
		if (curclust == 0)
			return -1;
		curclust = get_fatent_value(mydata, dir_curclust);
		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			printf("Invalid FAT entry\n");
			return -1;
		}

		dir_curclust = curclust;

		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
				mydata->clust_size * mydata->sect_size) != 0) {
			debug("Error: reading directory block\n");
			return -1;
		}

		slotptr2 = (dir_slot *)get_contents_vfatname_block;
		while (counter > 0) {
			if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
			    & 0xff) != counter)
				return -1;
			slotptr2++;
			counter--;
		}

		/* Save the real directory entry */
		realdent = (dir_entry *)slotptr2;
		while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
			slotptr2--;
			slot2str(slotptr2, l_name, &idx);
		}
	} else {
		/* Save the real directory entry */
		realdent = (dir_entry *)slotptr;
	}

	do {
		slotptr--;
		if (slot2str(slotptr, l_name, &idx))
			break;
	} while (!(slotptr->id & LAST_LONG_ENTRY_MASK));

	l_name[idx] = '\0';
	if (*l_name == DELETED_FLAG)
		*l_name = '\0';
	else if (*l_name == aRING)
		*l_name = DELETED_FLAG;
	downcase(l_name);

	/* Return the real directory entry */
	*retdent = realdent;

	if (slotptr2) {
		memcpy(get_dentfromdir_block, get_contents_vfatname_block,
			mydata->clust_size * mydata->sect_size);
		cur_position = (__u8 *)realdent - get_contents_vfatname_block;
		*retdent = (dir_entry *) &get_dentfromdir_block[cur_position];
	}

	return 0;
}

#endif

/*
 * Set the entry at index 'entry' in a FAT (16/32) table.
 */
static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
{
	__u32 bufnum, offset;
	__u32 off16;
	__u16 val;
	
	switch (mydata->fatsize) {
	case 32:
		bufnum = entry / FAT32BUFSIZE;
		offset = entry - bufnum * FAT32BUFSIZE;
		break;
	case 16:
		bufnum = entry / FAT16BUFSIZE;
		offset = entry - bufnum * FAT16BUFSIZE;
		break;
	case 12:
		bufnum = entry / FAT12BUFSIZE;
		offset = entry - bufnum * FAT12BUFSIZE;
		break;
	default:
		/* Unsupported FAT size */
		return -1;
	}

	/* Read a new block of FAT entries into the cache. */
	if (bufnum != mydata->fatbufnum) {
		int getsize = FATBUFBLOCKS;
		__u8 *bufptr = mydata->fatbuf;
		__u32 fatlength = mydata->fatlength;
		__u32 startblock = bufnum * FATBUFBLOCKS;

		fatlength *= mydata->sect_size;
		startblock += mydata->fat_sect;

		if (getsize > fatlength)
			getsize = fatlength;

		if (mydata->fatbufnum != -1) {
			if (flush_fat_buffer(mydata) < 0)
				return -1;
		}

		if (disk_read(startblock, getsize, bufptr) < 0) {
			debug("Error reading FAT blocks\n");
			return -1;
		}
		mydata->fatbufnum = bufnum;
	}

	/* Set the actual entry */
	switch (mydata->fatsize) {
	case 32:
		((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
		break;
	case 16:
		((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
		break;
	case 12:
		off16 = (offset * 3) / 4;

		switch (offset & 0x3) {
		case 0:
			val = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]&0xf000);
			((__u16 *) mydata->fatbuf)[off16]= val|(cpu_to_le16(entry_value)&0x0fff);		
			break;
		case 1:
			val = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]&0x0fff);
			((__u16 *)mydata->fatbuf)[off16] =val|((cpu_to_le16(entry_value)&0x000f)<<12);
			val = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]&0xff00);
			((__u16 *)mydata->fatbuf)[off16+1] =val|((cpu_to_le16(entry_value)&0x0ff0)>>4);
			break;
		case 2:
			val = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]&0x00ff);
			((__u16 *)mydata->fatbuf)[off16] =val|((cpu_to_le16(entry_value)&0x00ff)<<8);
			val = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]&0xfff0);
			((__u16 *)mydata->fatbuf)[off16+1] =val|((cpu_to_le16(entry_value)&0x0f00)>>8);
			break;
		case 3:
			val = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]&0x000f);
			((__u16 *) mydata->fatbuf)[off16]= val|((cpu_to_le16(entry_value)&0x0fff)<<4);		
			break;
		default:
			break;
		}
		break;
	default:
		return -1;
	}

	return 0;
}

/*
 * Determine the entry value at index 'entry' in a FAT (16/32) table
 */
static __u32 determine_fatent(fsdata *mydata, __u32 entry)
{
	__u32 next_fat, next_entry = entry + 1;

	while (1) {
		next_fat = get_fatent_value(mydata, next_entry);
		if (next_fat == 0) {
			set_fatent_value(mydata, entry, next_entry);
			break;
		}
		next_entry++;
	}
	debug("FAT%d: entry: %08x, entry_value: %04x\n",
	       mydata->fatsize, entry, next_entry);

	return next_entry;
}

/*
 * Write at most 'size' bytes from 'buffer' into the specified cluster.
 * Return 0 on success, -1 otherwise.
 */
static int
set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
	     unsigned long size)
{
	int idx = 0;
	__u32 startsect;

	if (clustnum > 0) {
		startsect = mydata->data_begin +
				clustnum * mydata->clust_size;
		
		if (mydata->fatsize!=32) {//this is for windows format
			if (startsect < mydata->rootdir_sect){
				debug("set_cluster\n");
				startsect=mydata->rootdir_sect;
			}
		}
	}
	else
		startsect = mydata->rootdir_sect;

	debug("clustnum: %d, startsect: %d\n", clustnum, startsect);

	if (disk_write(startsect, size / mydata->sect_size, buffer) < 0) {
		debug("Error writing data\n");
		return -1;
	}

	if (size % mydata->sect_size) {
		__u8 tmpbuf[mydata->sect_size];

		idx = size / mydata->sect_size;
		buffer += idx * mydata->sect_size;
		memcpy(tmpbuf, buffer, size % mydata->sect_size);

		if (disk_write(startsect + idx, 1, tmpbuf) < 0) {
			debug("Error writing data\n");
			return -1;
		}

		return 0;
	}

	return 0;
}

/*
 * Find the first empty cluster
 */
static int find_empty_cluster(fsdata *mydata)
{
	__u32 fat_val, entry = 3;

	while (1) {
		fat_val = get_fatent_value(mydata, entry);
		if (fat_val == 0)
			break;
		entry++;
	}

	return entry;
}

/*
 * Write directory entries in 'get_dentfromdir_block' to block device
 */
static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
{
	int dir_newclust = 0;

	if (set_cluster(mydata, dir_curclust,
		    get_dentfromdir_block,
		    mydata->clust_size * mydata->sect_size) != 0) {
		printf("error: wrinting directory entry\n");
		return;
	}
	dir_newclust = find_empty_cluster(mydata);
	set_fatent_value(mydata, dir_curclust, dir_newclust);
	if (mydata->fatsize == 32)
		set_fatent_value(mydata, dir_newclust, 0xffffff8);
	else if (mydata->fatsize == 16)
		set_fatent_value(mydata, dir_newclust, 0xfff8);
	else if (mydata->fatsize == 12)
		set_fatent_value(mydata, dir_newclust, 0xff8);

	dir_curclust = dir_newclust;

	if (flush_fat_buffer(mydata) < 0)
		return;

	memset(get_dentfromdir_block, 0x00,
		mydata->clust_size * mydata->sect_size);

	*dentptr = (dir_entry *) get_dentfromdir_block;
}

/*
 * Set empty cluster from 'entry' to the end of a file
 */
static int clear_fatent(fsdata *mydata, __u32 entry)
{
	__u32 fat_val;

	while (1) {
		fat_val = get_fatent_value(mydata, entry);
		if (fat_val != 0)
			set_fatent_value(mydata, entry, 0);
		else
			break;

		if (fat_val == 0xfffffff || fat_val == 0xffff)
			break;

		entry = fat_val;
	}

	/* Flush fat buffer */
	if (flush_fat_buffer(mydata) < 0)
		return -1;

	return 0;
}

/*
 * Write at most 'maxsize' bytes from 'buffer' into
 * the file associated with 'dentptr'
 * Return the number of bytes read or -1 on fatal errors.
 */
static int
set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
	      unsigned long maxsize)
{
	unsigned long filesize = FAT2CPU32(dentptr->size), gotsize = 0;
	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
	__u32 curclust = START(dentptr);
	__u32 endclust = 0, newclust = 0;
	unsigned long actsize;

	debug("Filesize: %ld bytes\n", filesize);
	if (maxsize > 0 && filesize > maxsize)
		filesize = maxsize;

	debug("%ld bytes\n", filesize);

	actsize = bytesperclust;
	endclust = curclust;
	do {
		/* search for consecutive clusters */
		while (actsize < filesize) {
			newclust = determine_fatent(mydata, endclust);

			if ((newclust - 1) != endclust)
				goto getit;

			if (CHECK_CLUST(newclust, mydata->fatsize)) {
				debug("curclust: 0x%x\n", newclust);
				debug("Invalid FAT entry\n");
				return gotsize;
			}
			endclust = newclust;
			actsize += bytesperclust;
		}
		/* actsize >= file size */
		actsize -= bytesperclust;
		/* set remaining clusters */
		if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
			debug("error: writing cluster\n");
			return -1;
		}

		/* set remaining bytes */
		gotsize += (int)actsize;
		filesize -= actsize;
		buffer += actsize;
		actsize = filesize;

		if (set_cluster(mydata, endclust, buffer, (int)actsize) != 0) {
			debug("error: writing cluster\n");
			return -1;
		}
		gotsize += actsize;

		/* Mark end of file in FAT */
		if (mydata->fatsize == 16)
			newclust = 0xffff;
		else if (mydata->fatsize == 32)
			newclust = 0xfffffff;
		else if (mydata->fatsize == 12)
			newclust = 0x0fff;
		debug("fatsize %d\n", mydata->fatsize);
		debug("data_begin 0x%x fatlength 0x%x fat_sect 0x%x clust_size 0x%x\n", 
			mydata->data_begin, mydata->fatlength, mydata->fat_sect,
			mydata->clust_size);

			
		set_fatent_value(mydata, endclust, newclust);
		debug("rootdir_sect 0x%x\n", mydata->rootdir_sect);

		return gotsize;
getit:
		if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
			debug("error: writing cluster\n");
			return -1;
		}
		gotsize += (int)actsize;
		filesize -= actsize;
		buffer += actsize;

		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			debug("Invalid FAT entry\n");
			return gotsize;
		}
		actsize = bytesperclust;
		curclust = endclust = newclust;
	} while (1);
}

/*
 * Fill dir_entry
 */
static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
	const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
{
	if (mydata->fatsize == 32)
		dentptr->starthi =
			cpu_to_le16((start_cluster & 0xffff0000) >> 16);
	dentptr->start = cpu_to_le16(start_cluster & 0xffff);
	dentptr->size = cpu_to_le32(size);

	dentptr->attr = attr;

	set_name(dentptr, filename);
}

/*
 * Check whether adding a file makes the file system to
 * exceed the size of the block device
 * Return -1 when overflow occurs, otherwise return 0
 */
static int check_overflow(fsdata *mydata, __u32 clustnum, unsigned long size)
{
	__u32 startsect, sect_num;

	if (clustnum > 0) {
		startsect = mydata->data_begin +
				clustnum * mydata->clust_size;
		
		if (mydata->fatsize!=32) {//this is for windows format
			if (startsect < mydata->rootdir_sect) {
				debug("check_overflow\n");
				startsect=mydata->rootdir_sect;
			}
		}
	} else {
		startsect = mydata->rootdir_sect;
	}

	sect_num = size / mydata->sect_size;
	if (size % mydata->sect_size)
		sect_num++;

	if (startsect + sect_num > cur_part_info.start + total_sector)
		return -1;

	return 0;
}

/*
 * Check if adding several entries exceed one cluster boundary
 */
static int is_next_clust(fsdata *mydata, dir_entry *dentptr)
{
	int cur_position;

	cur_position = (__u8 *)dentptr - get_dentfromdir_block;

	if (cur_position >= mydata->clust_size * mydata->sect_size)
		return 1;
	else
		return 0;
}

static dir_entry *empty_dentptr;
/*
 * Find a directory entry based on filename or start cluster number
 * If the directory entry is not found,
 * the new position for writing a directory entry will be returned
 */
static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
	char *filename, dir_entry *retdent, __u32 start)
{
	__u32 curclust = (startsect - mydata->data_begin) / mydata->clust_size;
	//if (mydata->fatsize != 32) {
	//	curclust=0;
	//}
	debug("get_dentfromdir: %s\n", filename);

	while (1) {
		dir_entry *dentptr;

		int i;

		if (get_cluster(mydata, curclust, get_dentfromdir_block,
			    mydata->clust_size * mydata->sect_size) != 0) {
			printf("Error: reading directory block\n");
			return NULL;
		}

		dentptr = (dir_entry *)get_dentfromdir_block;

		dir_curclust = curclust;

		for (i = 0; i < DIRENTSPERCLUST; i++) {
			char s_name[14], l_name[VFAT_MAXLEN_BYTES];

			l_name[0] = '\0';
			if (dentptr->name[0] == DELETED_FLAG) {
				dentptr++;
				if (is_next_clust(mydata, dentptr))
					break;
				continue;
			}
			if ((dentptr->attr & ATTR_VOLUME)) {
#ifdef CONFIG_SUPPORT_VFAT
				if ((dentptr->attr & ATTR_VFAT) &&
				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
					get_long_file_name(mydata, curclust,
						     get_dentfromdir_block,
						     &dentptr, l_name);
					debug("vfatname: |%s|\n", l_name);
				} else
#endif
				{
					/* Volume label or VFAT entry */
					dentptr++;
					if (is_next_clust(mydata, dentptr))
						break;
					continue;
				}
			}
			if (dentptr->name[0] == 0) {
				debug("Dentname == NULL - %d\n", i);
				empty_dentptr = dentptr;
				return NULL;
			}

			get_name(dentptr, s_name);

			if (strcmp(filename, s_name)
			    && strcmp(filename, l_name)) {
				debug("Mismatch: |%s|%s|\n",
					s_name, l_name);
				dentptr++;
				if (is_next_clust(mydata, dentptr))
					break;
				continue;
			}

			memcpy(retdent, dentptr, sizeof(dir_entry));

			debug("DentName: %s", s_name);
			debug(", start: 0x%x", START(dentptr));
			debug(", size:  0x%x %s\n",
			      FAT2CPU32(dentptr->size),
			      (dentptr->attr & ATTR_DIR) ?
			      "(DIR)" : "");

			return dentptr;
		}

		curclust = get_fatent_value(mydata, dir_curclust);
		if ((curclust >= 0xffffff8) || (curclust >= 0xfff8)) {
			empty_dentptr = dentptr;
			return NULL;
		}
		if (CHECK_CLUST(curclust, mydata->fatsize)) {
			debug("curclust: 0x%x\n", curclust);
			debug("Invalid FAT entry\n");
			return NULL;
		}
	}

	return NULL;
}

static int do_fat_write(const char *filename, void *buffer,
	unsigned long size)
{
	dir_entry *dentptr, *retdent;
	__u32 startsect;
	__u32 start_cluster;
	boot_sector bs;
	volume_info volinfo;
	fsdata datablock;
	fsdata *mydata = &datablock;
	int cursect;
	int ret = -1, name_len;
	char l_filename[VFAT_MAXLEN_BYTES];
	int write_size = size;

	dir_curclust = 0;

	if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
		debug("error: reading boot sector\n");
		return -1;
	}

	total_sector = bs.total_sect;
	if (total_sector == 0)
		total_sector = cur_part_info.size;

	if (mydata->fatsize == 32)
		mydata->fatlength = bs.fat32_length;
	else
		mydata->fatlength = bs.fat_length;

	mydata->fat_sect = bs.reserved;

	cursect = mydata->rootdir_sect
		= mydata->fat_sect + mydata->fatlength * bs.fats;
	debug("fat_sect %d numfat %d\n", mydata->fat_sect, bs.fats);
	num_of_fats = bs.fats;

	mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
	mydata->clust_size = bs.cluster_size;

	if (mydata->fatsize == 32) {
		mydata->data_begin = mydata->rootdir_sect -
					(mydata->clust_size * 2);
	} else {
		int rootdir_size;

		rootdir_size = ((bs.dir_entries[1]  * (int)256 +
				 bs.dir_entries[0]) *
				 sizeof(dir_entry)) /
				 mydata->sect_size;
		debug("rootdir_size 0x%x\n",rootdir_size);
		mydata->data_begin = mydata->rootdir_sect +
					rootdir_size -
					(mydata->clust_size * 2);
		debug("pre data_begin 0x%x\n", mydata->data_begin);
	}
	
	mydata->fatbufnum = -1;
	mydata->fatbuf = malloc(FATBUFSIZE);
	if (mydata->fatbuf == NULL) {
		debug("Error: allocating memory\n");
		return -1;
	}

	if (disk_read(cursect,
		(mydata->fatsize == 32) ?
		(mydata->clust_size) :
		PREFETCH_BLOCKS, do_fat_read_at_block) < 0) {
		debug("Error: reading rootdir block\n");
		goto exit;
	}
	dentptr = (dir_entry *) do_fat_read_at_block;

	name_len = strlen(filename);
	if (name_len >= VFAT_MAXLEN_BYTES)
		name_len = VFAT_MAXLEN_BYTES - 1;

	memcpy(l_filename, filename, name_len);
	l_filename[name_len] = 0; /* terminate the string */
	downcase(l_filename);

	startsect = mydata->rootdir_sect;
	debug("mydata->roodir_sect %d\n", startsect);
	retdent = find_directory_entry(mydata, startsect,
				l_filename, dentptr, 0);
	if (retdent) {
		/* Update file size and start_cluster in a directory entry */
		retdent->size = cpu_to_le32(size);
		start_cluster = FAT2CPU16(retdent->start);
		if (mydata->fatsize == 32)
			start_cluster |=
				(FAT2CPU16(retdent->starthi) << 16);

		ret = check_overflow(mydata, start_cluster, size);
		if (ret) {
			printf("Error: %ld overflow\n", size);
			goto exit;
		}

		ret = clear_fatent(mydata, start_cluster);
		if (ret) {
			printf("Error: clearing FAT entries\n");
			goto exit;
		}

		ret = set_contents(mydata, retdent, buffer, size);
		if (ret < 0) {
			printf("Error: writing contents\n");
			goto exit;
		}
		write_size = ret;
		debug("attempt to write 0x%x bytes\n", write_size);

		/* Flush fat buffer */
		ret = flush_fat_buffer(mydata);
		if (ret) {
			printf("Error: flush fat buffer\n");
			goto exit;
		}

		/* Write directory table to device */
		ret = set_cluster(mydata, dir_curclust,
			    get_dentfromdir_block,
			    mydata->clust_size * mydata->sect_size);
		if (ret) {
			printf("Error: writing directory entry\n");
			goto exit;
		}
	} else {
		/* Set short name to set alias checksum field in dir_slot */
		set_name(empty_dentptr, filename);
		fill_dir_slot(mydata, &empty_dentptr, filename);

		ret = start_cluster = find_empty_cluster(mydata);
		if (ret < 0) {
			printf("Error: finding empty cluster\n");
			goto exit;
		}

		ret = check_overflow(mydata, start_cluster, size);
		if (ret) {
			printf("Error: %ld overflow\n", size);
			goto exit;
		}

		/* Set attribute as archieve for regular file */
		fill_dentry(mydata, empty_dentptr, filename,
			start_cluster, size, 0x20);

		ret = set_contents(mydata, empty_dentptr, buffer, size);
		if (ret < 0) {
			printf("Error: writing contents\n");
			goto exit;
		}
		write_size = ret;
		debug("attempt to write 0x%x bytes\n", write_size);

		/* Flush fat buffer */
		ret = flush_fat_buffer(mydata);
		if (ret) {
			printf("Error: flush fat buffer\n");
			goto exit;
		}

		/* Write directory table to device */
		ret = set_cluster(mydata, dir_curclust,
			    get_dentfromdir_block,
			    mydata->clust_size * mydata->sect_size);
		if (ret) {
			printf("Error: writing directory entry\n");
			goto exit;
		}
	}

exit:
	free(mydata->fatbuf);
	return ret < 0 ? ret : write_size;
}

int file_fat_write(const char *filename, void *buffer, unsigned long maxsize)
{
	printf("writing %s\n", filename);
	return do_fat_write(filename, buffer, maxsize);
}





enum {
// Perhaps this should remain constant
	info_sector_number = 1,
// TODO: make these cmdline options
// dont forget sanity check: backup_boot_sector + 3 <= reserved_sect
	backup_boot_sector = 3,
	reserved_sect      = 6,
};

#define	NUM_FATS        2
#define MAX_CLUST_32    0x0FFFFFF0
#define MAX_CLUST_12    0x0FF0

#define FAT_FSINFO_SIG1 0x41615252
#define FAT_FSINFO_SIG2 0x61417272
#define BOOT_SIGN 0xAA55
#define MARK_CLUSTER(cluster, value) \
	((uint32_t *)fat)[cluster] = cpu_to_le32(value)
#define EOF_FAT32       0x0FFFFFF8
#define reserved_sect16or12 1

int
format_fat32(void)
{
	uint32_t sect_per_clust=1;
	uint32_t sect_per_fat=1;
	uint32_t total_clust;
	const char *volume_label = "";
	unsigned bufsize = reserved_sect;
	void *buffer;
	boot_sector32 *bs;
	fat32_fsinfo *fsinfo;

	if ((!strcmp(cur_part_info.type, "5")) ||
			(!strcmp(cur_part_info.type, "15"))||
			(!strcmp(cur_part_info.type, "133"))){
		printf("Cannot format extended partition!\n");
		return -1;
	}



	/* For FAT32, try to do the same as M$'s format command
	 * (see http://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf p. 20):
	 * fs size <= 260M: 0.5k clusters
	 * fs size <=	8G: 4k clusters
	 * fs size <=  16G: 8k clusters
	 * fs size >   16G: 16k clusters
	 */
	if (cur_part_info.size< 32.5*1024*2) {
		printf("The size of the device is too small for FAT32, please use FAT16/FAT12\n");
		return -1;
	} else if (cur_part_info.size> 260*1024*2) {
		sect_per_clust=8;
		if (cur_part_info.size>8*1024*1024*2) {
			sect_per_clust=16;
			if (cur_part_info.size>16*1024*1024*2) {
				sect_per_clust=32;
				if (cur_part_info.size>32*1024*1024*2) {
					sect_per_clust=64;
					if (cur_part_info.size>2*1024*1024*1024*2) {
						printf("FAT32 doesn't support larger than 2T\n");
						return -1;
					}
				}
			}
		}
		
	}
	sect_per_fat = 1;
	while (1) {
		while (1) {
			int spf_adj;
			unsigned int tcl = (cur_part_info.size - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust;
			// tcl may be > MAX_CLUST_32 here, but it may be
			// because sect_per_fat is underestimated,
			// and with increased sect_per_fat it still may become
			// <= MAX_CLUST_32. Therefore, we do not check
			// against MAX_CLUST_32, but against a bigger const:
			if (tcl > 0x80ffffff)
				goto next;
			total_clust = tcl; // fits in uint32_t
			// Every cluster needs 4 bytes in FAT. +2 entries since
			// FAT has space for non-existent clusters 0 and 1.
			// Let's see how many sectors that needs.
			//May overflow at "*4":
			//spf_adj = ((total_clust+2) * 4 + bytes_per_sect-1) / bytes_per_sect - sect_per_fat;
			//Same in the more obscure, non-overflowing form:
			spf_adj = ((total_clust+2) + (512/4)-1) / (512/4) - sect_per_fat;
#if 0
			printf("sect_per_clust:%u sect_per_fat:%u total_clust:%u",
					sect_per_clust, sect_per_fat, (int)tcl);
			printf("adjust to sect_per_fat:%d", spf_adj);
#endif
			if (spf_adj <= 0) {
				// do not need to adjust sect_per_fat.
				// so, was total_clust too big after all?
				if (total_clust <= MAX_CLUST_32)
					goto found_total_clust; // no
				// yes, total_clust is _a bit_ too big
				goto next;
			}
			// adjust sect_per_fat, go back and recalc total_clust
			// (note: just "sect_per_fat += spf_adj" isn't ok)
			sect_per_fat += ((unsigned)spf_adj / 2) | 1;
		}
 next:
		if (sect_per_clust == 128) {
			printf("can't make FAT32 with >128 sectors/cluster");
			return -1;
		}
		sect_per_clust *= 2;
		sect_per_fat = (sect_per_fat / 2) | 1;
	}
found_total_clust:	


	bufsize |= 2; // use this instead
	bufsize |= sect_per_clust;
	//printf("buffer size is 0x%x\n", bufsize);
	buffer = memalign(ARCH_DMA_MINALIGN, bufsize*512);
	if (buffer == NULL) {
		printf("Error: allocating block\n");
		return -1;
	}


	memset(buffer, 0, bufsize*512);
	bs=(void*)buffer;
	fsinfo=(void*)(buffer + 512);
	
	strcpy(bs->ignored, "\xeb\x58\x90" "MSWIN4.1"); // system_id[8] included :)
	STORE_LE(bs->sector_size[0], 0x00);//(__u16)cur_part_info.blksz);
	STORE_LE(bs->sector_size[1], 0x02);//(__u16)cur_part_info.blksz);
	STORE_LE(bs->cluster_size, (__u8)sect_per_clust);
	// cast in needed on big endian to suppress a warning
	STORE_LE(bs->reserved, (uint16_t)reserved_sect);
	STORE_LE(bs->fats, 2);
	//STORE_LE(bs->dir_entries[0], 0); // for FAT32, stays 0
	//STORE_LE(bs->dir_entries[1], 0); // for FAT32, stays 0
	//if (cur_part_info.size <= 0xffff) {
	//	STORE_LE(bs->sectors[0], (__u8)(cur_part_info.size&0xff));
	//	STORE_LE(bs->sectors[1], (__u8)((cur_part_info.size&0xff00)>>8));
	//}
	STORE_LE(bs->media, 0xf8);
	//STORE_LE(bs->fat_length, 0);
	STORE_LE(bs->secs_track, 63);
	STORE_LE(bs->heads, 255);
	STORE_LE(bs->hidden, 0);
	STORE_LE(bs->total_sect, cur_part_info.size);
	STORE_LE(bs->fat32_length, sect_per_fat);
	STORE_LE(bs->flags, 0);
	//STORE_LE(bs->version[0], 0);
	//STORE_LE(bs->version[1], 0);
	STORE_LE(bs->root_cluster, 2);
	STORE_LE(bs->info_sector, info_sector_number);
	STORE_LE(bs->backup_boot, backup_boot_sector);
	//STORE_LE(bs->reserved2[0], 0);
	//STORE_LE(bs->reserved2[1], 0);
	//STORE_LE(bs->reserved2[2], 0);
	//STORE_LE(bs->reserved2[3], 0);
	//STORE_LE(bs->reserved2[4], 0);
	//STORE_LE(bs->reserved2[5], 0);
	STORE_LE(bs->boot_signature, 0x29);
	//STORE_LE(bs->volumeID[0], 0);
	//STORE_LE(bs->volumeID[1], 0);
	//STORE_LE(bs->volumeID[2], 0);
	//STORE_LE(bs->volumeID[3], 0);
	strncpy(bs->filesystype, "FAT32   ", sizeof(bs->filesystype));
	strncpy(bs->volumelabel, volume_label, sizeof(bs->volumelabel));
	
	STORE_LE(fsinfo->signature1, FAT_FSINFO_SIG1);
	STORE_LE(fsinfo->signature2, FAT_FSINFO_SIG2);
	// we've allocated cluster 2 for the root dir
	STORE_LE(fsinfo->free_clusters, (total_clust - 1));
	STORE_LE(fsinfo->next_cluster, 2);
	STORE_LE(fsinfo->boot_sign, BOOT_SIGN);

	//set reserved region
	{
		*((__u8*)bs+510)=0x55;
		*((__u8*)bs+511)=0xAA;	
		*((__u8*)fsinfo+510)=0x55;
		*((__u8*)fsinfo+511)=0xAA;
		if (disk_write(0, backup_boot_sector, bs) < 0) {
			printf("Error: writing block\n");
			goto fail;
		}
		if (disk_write(backup_boot_sector, reserved_sect - backup_boot_sector, bs) < 0) {
			printf("Error: writing block\n");
			goto fail;
		}
	}
	
	//set fat
	{
		unsigned i=0,j=0;
		unsigned char *fat = (void*)buffer;
		memset(bs, 0, 512 * 2);
		// initial FAT entries
		MARK_CLUSTER(0, 0x0fffff00 | 0xf8);
		MARK_CLUSTER(1, 0xffffffff);
		// mark cluster 2 as EOF (used for root dir)
		MARK_CLUSTER(2, EOF_FAT32);
		for (i = 0; i < NUM_FATS; i++) {
			if (disk_write(reserved_sect+i*sect_per_fat, 1, buffer) < 0) {
				printf("Error: writing block\n");
				goto fail;
			}
			for (j = 1; j < sect_per_fat; j++)
				if (disk_write(reserved_sect+i*sect_per_fat+j, 1, buffer+512) < 0) {
					printf("Error: writing block\n");
					goto fail;
				}
		}
		memset(buffer, 0, sect_per_clust * 512);
		for(j=0;j<sect_per_clust;j++)
			if (disk_write(reserved_sect+i*sect_per_fat+j, 1, buffer) < 0) {
					printf("Error: writing block\n");
					goto fail;
				}
	}
	
	free(buffer);
	printf("succeed\n");
	return 0;
fail:
	printf("failed\n");
	free(buffer);
	return -1;
}

static void mark_FAT_cluster(char size_fat, char* fat, int cluster, unsigned int value)
{
    switch (size_fat) {
    case 12:
	value &= 0x0fff;
	if (((cluster * 3) & 0x1) == 0) {
	    fat[3 * cluster / 2] = (unsigned char)(value & 0x00ff);
	    fat[(3 * cluster / 2) + 1] =
		(unsigned char)((fat[(3 * cluster / 2) + 1] & 0x00f0)
				| ((value & 0x0f00) >> 8));
	} else {
	    fat[3 * cluster / 2] =
		(unsigned char)((fat[3 * cluster / 2] & 0x000f) |
				((value & 0x000f) << 4));
	    fat[(3 * cluster / 2) + 1] = (unsigned char)((value & 0x0ff0) >> 4);
	}
	break;

    case 16:
	value &= 0xffff;
	fat[2 * cluster] = (unsigned char)(value & 0x00ff);
	fat[(2 * cluster) + 1] = (unsigned char)(value >> 8);
	break;

    case 32:
	value &= 0xfffffff;
	fat[4 * cluster] = (unsigned char)(value & 0x000000ff);
	fat[(4 * cluster) + 1] = (unsigned char)((value & 0x0000ff00) >> 8);
	fat[(4 * cluster) + 2] = (unsigned char)((value & 0x00ff0000) >> 16);
	fat[(4 * cluster) + 3] = (unsigned char)((value & 0xff000000) >> 24);
	break;

    default:
	printf("Bad FAT size (not 12, 16, or 32)\n");
    }
}


int
format_fat16(void)
{
	uint32_t sect_per_clust=1;
	uint32_t sect_per_fat=1;
	uint32_t total_clust;
	const char *volume_label = "";
	unsigned bufsize = reserved_sect;
	void *buffer;
	boot_sector16or12 *bs;

	if ((!strcmp(cur_part_info.type, "5")) ||
			(!strcmp(cur_part_info.type, "15"))||
			(!strcmp(cur_part_info.type, "133"))){
		printf("Cannot format extended partition!\n");
		return -1;
	}


	/* For FAT32, try to do the same as M$'s format command
	 * (see http://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf p. 20):
	 * fs size <= 260M: 0.5k clusters
	 * fs size <=	8G: 4k clusters
	 * fs size <=  16G: 8k clusters
	 * fs size >   16G: 16k clusters
	 */
	if (cur_part_info.size< 4.1*1024*2) {
		printf("The size of the device is too small for FAT16, please use FAT12\n");
		return -1;
	} else if (cur_part_info.size> 16*1024*2) {
		sect_per_clust=4;
		if (cur_part_info.size>128*1024*2) {
			sect_per_clust=8;
			if (cur_part_info.size>256*1024*2) {
				sect_per_clust=16;
				if (cur_part_info.size>512*1024*2) {
					sect_per_clust=32;
					if (cur_part_info.size>1024*1024*2) {
						sect_per_clust=64;
						if (cur_part_info.size>2*1024*1024*2){
							printf("FAT16 doesn't support larger than 2G\n");
							return -1;
						}
					}
					
				}
			}
		}
		
	}
	//we have to decide sect_per_fat
	{
		unsigned int RootDirSectors = ((512*32)+(512-1))/512;
		unsigned int TmpVal1 = cur_part_info.size-(1+RootDirSectors);
		unsigned int TmpVal2 = (256*sect_per_clust)+2;;
		unsigned int FATSz = (TmpVal1+TmpVal2-1)/TmpVal2;
		sect_per_fat = FATSz;
	}


	debug("sect_per_fat 0x%x\n", sect_per_fat);
	debug("sect_per_clust 0x%x\n", sect_per_clust);
	bufsize |= 2; // use this instead
	bufsize |= sect_per_clust;
	buffer = memalign(ARCH_DMA_MINALIGN, bufsize*512);
	if (buffer == NULL) {
		printf("Error: allocating block\n");
		return -1;
	}


	memset(buffer, 0, bufsize*512);
	bs=(void*)buffer;
	
	strcpy(bs->ignored, "\xeb\x58\x90" "MSWIN4.1"); // system_id[8] included :)
	STORE_LE(bs->sector_size[0], 0x00);//(__u16)cur_part_info.blksz);
	STORE_LE(bs->sector_size[1], 0x02);//(__u16)cur_part_info.blksz);
	STORE_LE(bs->cluster_size, (__u8)sect_per_clust);
	// cast in needed on big endian to suppress a warning
	STORE_LE(bs->reserved, 1);
	STORE_LE(bs->fats, 2);
	STORE_LE(bs->dir_entries[0], 0x00); 
	STORE_LE(bs->dir_entries[1], 0x02); 
	if (cur_part_info.size <= 0xffff) {
		STORE_LE(bs->sectors[0], (__u8)(cur_part_info.size&0xff));
		STORE_LE(bs->sectors[1], (__u8)((cur_part_info.size&0xff00)>>8));
	}
	STORE_LE(bs->media, 0xf8);
	STORE_LE(bs->fat_length, sect_per_fat);
	STORE_LE(bs->secs_track, 63);
	STORE_LE(bs->heads, 255);
	STORE_LE(bs->hidden, 0);
	STORE_LE(bs->total_sect, cur_part_info.size);
	STORE_LE(bs->drive_number, 0);
	STORE_LE(bs->boot_signature, 0x29);
	//STORE_LE(bs->volumeID[0], 0);
	//STORE_LE(bs->volumeID[1], 0);
	//STORE_LE(bs->volumeID[2], 0);
	//STORE_LE(bs->volumeID[3], 0);
	strncpy(bs->filesystype, "FAT16   ", sizeof(bs->filesystype));
	strncpy(bs->volumelabel, volume_label, sizeof(bs->volumelabel));
	

	//set reserved region
	{
		*((__u8*)bs+510)=0x55;
		*((__u8*)bs+511)=0xAA;	
		if (disk_write(0, 1, bs) < 0) {
			printf("Error: writing block\n");
			goto fail;
		}
	}
	
	
	{
		//set fat
		unsigned i=0,j=0;
		unsigned char *fat = (void*)buffer;
		memset(bs, 0, 512 * 2);
		// initial FAT entries
		mark_FAT_cluster(16, fat, 0, 0xfffffff8);
		mark_FAT_cluster(16, fat, 1, 0xffffffff);
		for (i = 0; i < NUM_FATS; i++) {
			if (disk_write(1+i*sect_per_fat, 1, buffer) < 0) {
				printf("Error: writing block\n");
				goto fail;
			}
			for (j = 1; j < sect_per_fat; j++)
				if (disk_write(1+i*sect_per_fat+j, 1, buffer+512) < 0) {
					printf("Error: writing block\n");
					goto fail;
				}
		}
		
		//set root directory region
		
		memset(buffer, 0, 512);
		for(j=0;j<32;j++)
			if (disk_write(1+NUM_FATS*sect_per_fat+j, 1, buffer) < 0) {
					printf("Error: writing block\n");
					goto fail;
			}
	}
	
	free(buffer);
	printf("succeed\n");
	return 0;
fail:
	printf("failed\n");
	free(buffer);
	return -1;
}

int
format_fat12(void)
{
		uint32_t sect_per_clust=0x40;
		uint32_t sect_per_fat=1;
		uint32_t total_clust;
		const char *volume_label = "";
		unsigned bufsize = reserved_sect;
		void *buffer;
		boot_sector16or12 *bs;

		if ((!strcmp(cur_part_info.type, "5")) ||
				(!strcmp(cur_part_info.type, "15"))||
				(!strcmp(cur_part_info.type, "133"))){
			printf("Cannot format extended partition!\n");
			return -1;
		}


	
		/* For FAT32, try to do the same as M$'s format command
		 * (see http://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf p. 20):
		 * fs size <= 260M: 0.5k clusters
		 * fs size <=	8G: 4k clusters
		 * fs size <=  16G: 8k clusters
		 * fs size >   16G: 16k clusters
		 */
		if (cur_part_info.size > 255*63) {
			printf("The size is larger than 7.8MB, Please use the FAT16/FAT32\n");
			return -1;
		}

		//we have to decide sect_per_fat
		sect_per_fat=0x0c;	
		sect_per_clust=4;
	
		bufsize |= 2; // use this instead
		bufsize |= sect_per_clust;
		buffer = memalign(ARCH_DMA_MINALIGN, bufsize*512);
		if (buffer == NULL) {
			printf("Error: allocating block\n");
			return -1;
		}
	
	
		memset(buffer, 0, bufsize*512);
		bs=(void*)buffer;
		
		strcpy(bs->ignored, "\xeb\x58\x90" "MSWIN4.1"); // system_id[8] included :)
		STORE_LE(bs->sector_size[0], 0x00);//(__u16)cur_part_info.blksz);
		STORE_LE(bs->sector_size[1], 0x02);//(__u16)cur_part_info.blksz);
		STORE_LE(bs->cluster_size, (__u8)sect_per_clust);
		// cast in needed on big endian to suppress a warning
		STORE_LE(bs->reserved, sect_per_clust);
		STORE_LE(bs->fats, 2);
		STORE_LE(bs->dir_entries[0], 0x00); 
		STORE_LE(bs->dir_entries[1], 0x02); 
		if (cur_part_info.size <= 0xffff) {
			STORE_LE(bs->sectors[0], (__u8)(cur_part_info.size&0xff));
			STORE_LE(bs->sectors[1], (__u8)((cur_part_info.size&0xff00)>>8));
		}
		STORE_LE(bs->media, 0xf8);
		STORE_LE(bs->fat_length, sect_per_fat);
		STORE_LE(bs->secs_track, 63);
		STORE_LE(bs->heads, 255);
		STORE_LE(bs->hidden, 0);
		STORE_LE(bs->total_sect, cur_part_info.size);
		STORE_LE(bs->drive_number, 0);
		STORE_LE(bs->boot_signature, 0x29);
		//STORE_LE(bs->volumeID[0], 0);
		//STORE_LE(bs->volumeID[1], 0);
		//STORE_LE(bs->volumeID[2], 0);
		//STORE_LE(bs->volumeID[3], 0);
		strncpy(bs->filesystype, "FAT12   ", sizeof(bs->filesystype));
		strncpy(bs->volumelabel, volume_label, sizeof(bs->volumelabel));
		
	
		//set reserved region
		{
			*((__u8*)bs+510)=0x55;
			*((__u8*)bs+511)=0xAA;	
			if (disk_write(0, 1, bs) < 0) {
				printf("Error: writing block\n");
				goto fail;
			}
		}
		
		
		{
			//set fat
			unsigned i=0,j=0;
			unsigned int reserver12=sect_per_clust;
			unsigned char *fat = (void*)buffer;
			memset(bs, 0, 512 * 2);
			// initial FAT entries
			mark_FAT_cluster(12, fat, 0, 0xfffffff8);
			mark_FAT_cluster(12, fat, 1, 0xffffffff);
			
			for (i = 0; i < NUM_FATS; i++) {
				if (disk_write(reserver12+i*sect_per_fat, 1, buffer) < 0) {
					printf("Error: writing block\n");
					goto fail;
				}
				for (j = 1; j < sect_per_fat; j++)
					if (disk_write(reserver12+i*sect_per_fat+j, 1, buffer+512) < 0) {
						printf("Error: writing block\n");
						goto fail;
					}
			}
			
			//set root directory region
			
			memset(buffer, 0, 512);
			for(j=0;j<32;j++)
				if (disk_write(reserver12+NUM_FATS*sect_per_fat+j, 1, buffer) < 0) {
						printf("Error: writing block\n");
						goto fail;
				}
		}
		
		free(buffer);
		printf("succeed\n");
		return 0;
	fail:
		printf("failed\n");
		free(buffer);
		return -1;

}