Moved driver to 'drivers' subdir

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@189 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 1315 insertions, 0 deletions

diff --git a/firmware/drivers/fat.c b/firmware/drivers/fat.c
new file mode 100644
index 0000000000..328428a941
--- /dev/null
+++ b/firmware/drivers/fat.c
@@ -0,0 +1,1315 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2002 by Linus Nielsen Feltzing
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <time.h>
+#include <sys/timeb.h>
+
+#define BLOCK_SIZE 512
+
+#include "fat.h"
+#include "ata.h"
+
+#define NUM_ROOT_DIR_ENTRIES 512
+#define NUM_FATS 2
+#define NUM_RESERVED_SECTORS 1
+#define NUM_BLOCKS 10000
+
+struct dsksz2secperclus
+{
+        unsigned int disk_size;
+        unsigned int sec_per_cluster;
+};
+
+/*
+** This is the table for FAT16 drives. NOTE that this table includes
+** entries for disk sizes larger than 512 MB even though typically
+** only the entries for disks < 512 MB in size are used.
+** The way this table is accessed is to look for the first entry
+** in the table for which the disk size is less than or equal
+** to the DiskSize field in that table entry. For this table to
+** work properly BPB_RsvdSecCnt must be 1, BPB_NumFATs
+** must be 2, and BPB_RootEntCnt must be 512. Any of these values
+** being different may require the first table entries DiskSize value
+** to be changed otherwise the cluster count may be to low for FAT16.
+*/
+struct dsksz2secperclus dsk_table_fat16 [] =
+{
+    { 8400, 0}, /* disks up to 4.1 MB, the 0 value for SecPerClusVal
+                   trips an error */
+    { 32680, 2}, /* disks up to 16 MB, 1k cluster */
+    { 262144, 4}, /* disks up to 128 MB, 2k cluster */
+    { 524288, 8}, /* disks up to 256 MB, 4k cluster */
+    { 1048576, 16}, /* disks up to 512 MB, 8k cluster */
+/* The entries after this point are not used unless FAT16 is forced */
+    { 2097152, 32}, /* disks up to 1 GB, 16k cluster */
+    { 4194304, 64}, /* disks up to 2 GB, 32k cluster */
+    { 0xFFFFFFFF, 0} /* any disk greater than 2GB,
+                        0 value for SecPerClusVal trips an error */
+};
+
+int fat_num_rootdir_sectors(struct bpb *bpb);
+int fat_first_sector_of_cluster(struct bpb *bpb, unsigned int cluster);
+int fat_get_fatsize(struct bpb* bpb);
+int fat_get_totsec(struct bpb* bpb);
+int fat_get_rootdir_sector(struct bpb *bpb);
+int fat_first_data_sector(struct bpb* bpb);
+int fat_get_bpb(struct bpb *bpb);
+int fat_bpb_is_sane(struct bpb *bpb);
+int fat_create_fat(struct bpb* bpb);
+int fat_dbg_read_block(char *name, unsigned char *buf);
+int fat_flush_fat(struct bpb *bpb);
+unsigned char *fat_cache_fat_sector(struct bpb *bpb, int secnum);
+int fat_update_entry(struct bpb *bpb, int entry, unsigned int val);
+unsigned int fat_getcurrdostime(unsigned short *dosdate,
+                                unsigned short *dostime,
+                                unsigned char *dostenth);
+int fat_create_root_dir(struct bpb *bpb);
+int fat_create_dos_name(unsigned char *name, unsigned char *newname);
+int fat_create_file(struct bpb *bpb, unsigned int currdir, char *name);
+
+unsigned char *fat_cache[256];
+int fat_cache_dirty[256];
+char current_directory[256] = "\\";
+struct bpb *global_bpb;
+struct disk_info di;
+
+extern int yyparse(void);
+
+
+#ifdef TEST_FAT
+void prompt(void)
+{
+   printf("C:%s>", current_directory);
+}
+
+int main(int argc, char *argv[])
+{
+    struct bpb bpb;
+    
+    memset(fat_cache, 0, sizeof(fat_cache));
+    memset(fat_cache_dirty, 0, sizeof(fat_cache_dirty));
+    
+    disk_init(NUM_BLOCKS);
+
+    di.num_sectors = NUM_BLOCKS;
+    di.sec_per_track = 40;
+    di.num_heads = 250;
+    di.hidden_sectors = 0;
+
+    if(read_disk("diskdump.dmp") < 0)
+    {
+        printf("*** Warning! The disk is uninitialized\n");
+    }
+    else
+    {
+        fat_get_bpb(&bpb);
+    }
+
+    global_bpb = &bpb;
+    prompt();
+    yyparse();
+
+    dump_disk("diskdump.dmp");
+    return 0;
+}
+#endif
+
+int fat_sec2cluster(struct bpb *bpb, unsigned int sec)
+{
+    int first_sec = fat_first_data_sector(bpb);
+    
+    if(sec < first_sec)
+    {
+        fprintf(stderr, "fat_sec2cluster() - Bad sector number (%d)\n", sec);
+        return -1;
+    }
+
+    return ((sec - first_sec) / bpb->bpb_secperclus) + 2;
+}
+
+int fat_last_cluster_in_chain(struct bpb *bpb, unsigned int cluster)
+{
+    int iseof = 0;
+
+    switch(bpb->fat_type)
+    {
+        case FATTYPE_FAT12:
+            if(cluster >= 0x0ff8)
+                iseof = 1;
+            break;
+        case FATTYPE_FAT16:
+            if(cluster >= 0xfff8)
+                iseof = 1;
+            break;
+        case FATTYPE_FAT32:
+            if(cluster >= 0x0ffffff8)
+                iseof = 1;
+            break;
+    }
+    return iseof;
+}
+
+int fat_cluster2sec(struct bpb *bpb, unsigned int cluster)
+{
+    int max_cluster = (fat_get_totsec(bpb) - fat_first_data_sector(bpb)) /
+        bpb->bpb_secperclus + 1;
+    
+    if(cluster > max_cluster)
+    {
+        fprintf(stderr, "fat_cluster2sec() - Bad cluster number (%d)\n",
+                cluster);
+        return -1;
+    }
+
+    return fat_first_sector_of_cluster(bpb, cluster);
+}
+
+int fat_first_sector_of_cluster(struct bpb *bpb, unsigned int cluster)
+{
+    return (cluster - 2) * bpb->bpb_secperclus + fat_first_data_sector(bpb);
+}
+
+int fat_num_rootdir_sectors(struct bpb *bpb)
+{
+    return ((bpb->bpb_rootentcnt * 32) + (bpb->bpb_bytspersec - 1)) /
+           bpb->bpb_bytspersec;
+}
+
+int fat_get_fatsize(struct bpb* bpb)
+{
+    if(bpb->bpb_fatsz16 != 0)
+        return bpb->bpb_fatsz16;
+    else
+        return bpb->bpb_fatsz32;
+}
+
+int fat_get_totsec(struct bpb* bpb)
+{
+    if(bpb->bpb_totsec16 != 0)
+        return bpb->bpb_totsec16;
+    else
+        return bpb->bpb_totsec32;
+}
+
+int fat_get_rootdir_sector(struct bpb *bpb)
+{
+    return bpb->bpb_rsvdseccnt + bpb->bpb_numfats * fat_get_fatsize(bpb);
+}
+
+int fat_first_data_sector(struct bpb* bpb)
+{
+    int fatsz;
+    int rootdirsectors;
+
+    fatsz = fat_get_fatsize(bpb);
+
+    rootdirsectors = fat_num_rootdir_sectors(bpb);
+    
+    return bpb->bpb_rsvdseccnt + bpb->bpb_numfats * fatsz + rootdirsectors;
+}
+
+int fat_format(struct disk_info *di, char *vol_name)
+{
+    unsigned char buf[BLOCK_SIZE];
+    struct bpb bpb;
+    unsigned int root_dir_sectors;
+    unsigned int tmp1, tmp2;
+    int sec_per_clus = 0;
+    int fat_size;
+    int i = 0;
+    int err;
+
+    while(di->num_sectors > dsk_table_fat16[i].disk_size)
+    {
+        i++;
+    }
+
+    sec_per_clus = dsk_table_fat16[i].sec_per_cluster;
+    
+    if(sec_per_clus == 0)
+    {
+        fprintf(stderr, "fat_format() - Bad disk size (%u)\n",
+                di->num_sectors);
+        return -1;
+    }
+
+    /* First calculate how many sectors we need for
+       the root directory */
+    root_dir_sectors = ((NUM_ROOT_DIR_ENTRIES * 32) +
+                        (BLOCK_SIZE - 1)) / BLOCK_SIZE;
+
+    /* Now calculate the FAT size */
+    tmp1 = di->num_sectors - (NUM_RESERVED_SECTORS + root_dir_sectors);
+    tmp2 = (256 * sec_per_clus) + NUM_FATS;
+
+    fat_size = (tmp1 + (tmp2 - 1)) / tmp2;
+
+    /* Now create the BPB. We must be careful, so we really make
+       it little endian. */
+    memset(buf, 0xff, BLOCK_SIZE);
+
+    strncpy(&buf[BS_OEMNAME], "MSWIN4.1", 8);
+    buf[BPB_BYTSPERSEC] = BLOCK_SIZE & 0xff;
+    buf[BPB_BYTSPERSEC+1] = BLOCK_SIZE >> 8;
+    buf[BPB_SECPERCLUS] = sec_per_clus;
+    buf[BPB_RSVDSECCNT] = 1;
+    buf[BPB_RSVDSECCNT+1] = 0;
+    buf[BPB_NUMFATS] = 2;
+    buf[BPB_ROOTENTCNT] = NUM_ROOT_DIR_ENTRIES & 0xff;
+    buf[BPB_ROOTENTCNT+1] = NUM_ROOT_DIR_ENTRIES >> 8;
+    buf[BPB_TOTSEC16] = di->num_sectors & 0xff;
+    buf[BPB_TOTSEC16+1] = di->num_sectors >> 8;
+    buf[BPB_MEDIA] = 0xf0;
+    buf[BPB_FATSZ16] = fat_size & 0xff;
+    buf[BPB_FATSZ16+1] = fat_size >> 8;
+    buf[BPB_SECPERTRK] = di->sec_per_track & 0xff;
+    buf[BPB_SECPERTRK+1] = di->sec_per_track >> 8;
+    buf[BPB_NUMHEADS] = di->num_heads & 0xff;
+    buf[BPB_NUMHEADS+1] = di->num_heads >> 8;
+    buf[BPB_HIDDSEC] = di->hidden_sectors & 0xff;
+    buf[BPB_HIDDSEC+1] = (di->hidden_sectors >> 8) & 0xff;
+    buf[BPB_HIDDSEC+2] = (di->hidden_sectors >> 16) & 0xff;
+    buf[BPB_HIDDSEC+3] = (di->hidden_sectors >> 24) & 0xff;
+    buf[BPB_TOTSEC32] = 0;
+    buf[BPB_TOTSEC32+1] = 0;
+    buf[BPB_TOTSEC32+2] = 0;
+    buf[BPB_TOTSEC32+3] = 0;
+
+    buf[BS_DRVNUM] = 0;
+    buf[BS_RESERVED1] = 0;
+    buf[BS_BOOTSIG] = 0x29;
+    buf[BS_VOLID] = 0x78;
+    buf[BS_VOLID+1] = 0x56;
+    buf[BS_VOLID+2] = 0x34;
+    buf[BS_VOLID+3] = 0x12;
+    memset(&buf[BS_VOLLAB], ' ', 11);
+    strncpy(&buf[BS_VOLLAB], vol_name, MIN(11, strlen(vol_name));
+    strncpy(&buf[BS_FILSYSTYPE], "FAT16   ", 8);
+
+    /* The final signature */
+    buf[BPB_LAST_WORD] = 0x55;
+    buf[BPB_LAST_WORD+1] = 0xaa;
+
+    /* Now write the sector to disk */
+    err = ata_write_sectors(0,1,buf);
+    if(err)
+    {
+        fprintf(stderr, "fat_format() - Couldn't write BSB (error code %i)\n",
+                err);
+        return -1;
+    }
+
+    if(fat_get_bpb(&bpb) < 0)
+    {
+        fprintf(stderr, "fat_format() - Couldn't read BPB\n");
+        return -1;
+    }
+
+    if(fat_create_fat(&bpb) < 0)
+    {
+        fprintf(stderr, "fat_format() - Couldn't create FAT\n");
+        return -1;
+    }
+    
+    if(fat_create_root_dir(&bpb) < 0)
+    {
+        fprintf(stderr, "fat_format() - Couldn't write root dir sector\n");
+        return -1;
+    }
+    
+    return 0;
+}
+
+int fat_get_bpb(struct bpb *bpb)
+{
+    unsigned char buf[BLOCK_SIZE];
+    int err;
+    int fatsz;
+    int rootdirsectors;
+    int totsec;
+    int datasec;
+    int countofclusters;
+
+    /* Read the sector */
+    err = ata_read_sectors(0,1,buf);
+    if(err)
+    {
+        fprintf(stderr, "fat_get_bpb() - Couldn't read BPB (error code %i)\n",
+                err);
+        return -1;
+    }
+
+    memset(bpb, 0, sizeof(struct bpb));
+    
+    strncpy(bpb->bs_oemname, &buf[BS_OEMNAME], 8);
+    bpb->bs_oemname[8] = 0;
+
+    bpb->bpb_bytspersec = buf[BPB_BYTSPERSEC] | (buf[BPB_BYTSPERSEC+1] << 8);
+    bpb->bpb_secperclus = buf[BPB_SECPERCLUS];
+    bpb->bpb_rsvdseccnt = buf[BPB_RSVDSECCNT] | (buf[BPB_RSVDSECCNT+1] << 8);
+    bpb->bpb_numfats = buf[BPB_NUMFATS];
+    bpb->bpb_rootentcnt = buf[BPB_ROOTENTCNT] | (buf[BPB_ROOTENTCNT+1] << 8);
+    bpb->bpb_totsec16 = buf[BPB_TOTSEC16] | (buf[BPB_TOTSEC16+1] << 8);
+    bpb->bpb_media = buf[BPB_MEDIA];
+    bpb->bpb_fatsz16 = buf[BPB_FATSZ16] | (buf[BPB_FATSZ16+1] << 8);
+    bpb->bpb_secpertrk = buf[BPB_SECPERTRK] | (buf[BPB_SECPERTRK+1] << 8);
+    bpb->bpb_numheads = buf[BPB_NUMHEADS] | (buf[BPB_NUMHEADS+1] << 8);
+    bpb->bpb_hiddsec = buf[BPB_HIDDSEC] | (buf[BPB_HIDDSEC+1] << 8) |
+        (buf[BPB_HIDDSEC+2] << 16) | (buf[BPB_HIDDSEC+3] << 24);
+    bpb->bpb_totsec32 = buf[BPB_TOTSEC32] | (buf[BPB_TOTSEC32+1] << 8) |
+        (buf[BPB_TOTSEC32+2] << 16) | (buf[BPB_TOTSEC32+3] << 24);
+
+    bpb->bs_drvnum = buf[BS_DRVNUM];
+    bpb->bs_bootsig = buf[BS_BOOTSIG];
+    if(bpb->bs_bootsig == 0x29)
+    {
+        bpb->bs_volid = buf[BS_VOLID] | (buf[BS_VOLID+1] << 8) |
+            (buf[BS_VOLID+2] << 16) | (buf[BS_VOLID+3] << 24);
+        strncpy(bpb->bs_vollab, &buf[BS_VOLLAB], 11);
+        strncpy(bpb->bs_filsystype, &buf[BS_FILSYSTYPE], 8);
+    }
+
+    bpb->bpb_fatsz32 = (buf[BPB_FATSZ32] + (buf[BPB_FATSZ32+1] << 8)) |
+        (buf[BPB_FATSZ32+2] << 16) | (buf[BPB_FATSZ32+3] << 24);
+    
+    bpb->last_word = buf[BPB_LAST_WORD] | (buf[BPB_LAST_WORD+1] << 8);
+
+    /* Determine FAT type */
+    fatsz = fat_get_fatsize(bpb);
+
+    if(bpb->bpb_totsec16 != 0)
+        totsec = bpb->bpb_totsec16;
+    else
+        totsec = bpb->bpb_totsec32;
+
+    rootdirsectors = fat_num_rootdir_sectors(bpb);
+    datasec = totsec - (bpb->bpb_rsvdseccnt + bpb->bpb_numfats * fatsz +
+                        rootdirsectors);
+    countofclusters = datasec / bpb->bpb_secperclus;
+
+    if(countofclusters < 4085)
+    {
+        bpb->fat_type = FATTYPE_FAT12;
+    }
+    else
+    {
+        if(countofclusters < 65525)
+        {
+            bpb->fat_type = FATTYPE_FAT16;
+        }
+        else
+        {
+            bpb->fat_type = FATTYPE_FAT32;
+        }
+    }
+
+    if(fat_bpb_is_sane(bpb) < 0)
+    {
+        fprintf(stderr, "fat_get_bpb() - BPB is not sane\n");
+        return -1;
+    }
+
+    return 0;
+}
+
+int fat_bpb_is_sane(struct bpb *bpb)
+{
+    if(bpb->fat_type == FATTYPE_FAT32)
+    {
+        fprintf(stderr, "fat_bpb_is_sane() - Error: FAT32 not supported\n");
+        return -1;
+    }
+    
+    if(bpb->bpb_bytspersec != 512)
+    {
+        fprintf(stderr,
+                "fat_bpb_is_sane() - Warning: sector size is not 512 (%i)\n",
+                bpb->bpb_bytspersec);
+    }
+    if(bpb->bpb_secperclus * bpb->bpb_bytspersec > 32768)
+    {
+        fprintf(stderr,
+                "fat_bpb_is_sane() - Warning: cluster size is larger than 32K "
+                "(%i * %i = %i)\n",
+                bpb->bpb_bytspersec, bpb->bpb_secperclus,
+                bpb->bpb_bytspersec * bpb->bpb_secperclus);
+    }
+    if(bpb->bpb_rsvdseccnt != 1)
+    {
+        fprintf(stderr,
+                "fat_bpb_is_sane() - Warning: Reserved sectors is not 1 (%i)\n",
+                bpb->bpb_rsvdseccnt);
+    }
+    if(bpb->bpb_numfats != 2)
+    {
+        fprintf(stderr,
+                "fat_bpb_is_sane() - Warning: NumFATS is not 2 (%i)\n",
+                bpb->bpb_numfats);
+    }
+    if(bpb->bpb_rootentcnt != 512)
+    {
+        fprintf(stderr,
+                "fat_bpb_is_sane() - Warning: RootEntCnt is not 512 (%i)\n",
+                bpb->bpb_rootentcnt);
+    }
+    if(bpb->bpb_totsec16 < 200)
+    {
+        if(bpb->bpb_totsec16 == 0)
+        {
+            fprintf(stderr, "fat_bpb_is_sane() - Error: TotSec16 is 0\n");
+            return -1;
+        }
+        else
+        {
+            fprintf(stderr,
+                    "fat_bpb_is_sane() - Warning: TotSec16 "
+                    "is quite small (%i)\n",
+                    bpb->bpb_totsec16);
+        }
+    }
+    if(bpb->bpb_media != 0xf0 && bpb->bpb_media < 0xf8)
+    {
+        fprintf(stderr,
+                "fat_bpb_is_sane() - Warning: Non-standard "
+                "media type (0x%02x)\n",
+                bpb->bpb_media);
+    }
+    if(bpb->last_word != 0xaa55)
+    {
+        fprintf(stderr, "fat_bpb_is_sane() - Error: Last word is not "
+                "0xaa55 (0x%04x)\n", bpb->last_word);
+        return -1;
+    }
+    return 0;
+}
+
+int fat_create_fat(struct bpb* bpb)
+{
+    unsigned char *sec;
+    int i;
+    int secnum = 0;
+    int fatsz;
+
+    if(fat_bpb_is_sane(bpb) < 0)
+    {
+        fprintf(stderr, "fat_create_fat() - BPB is not sane\n");
+        return -1;
+    }
+
+    if(bpb->bpb_fatsz16 != 0)
+        fatsz = bpb->bpb_fatsz16;
+    else
+        fatsz = bpb->bpb_fatsz32;
+
+    sec = fat_cache_fat_sector(bpb, secnum);
+    if(!sec)
+    {
+        fprintf(stderr, "fat_create_fat() - Couldn't cache fat sector"
+                " (%d)\n", secnum);
+        return -1;
+    }
+
+    fat_cache_dirty[secnum] = 1;
+    
+    /* First entry should have the media type in the
+       low byte and the rest of the bits set to 1.
+       The second should be the EOC mark. */
+    memset(sec, 0, BLOCK_SIZE);
+    sec[0] = bpb->bpb_media;
+    if(bpb->fat_type == FATTYPE_FAT12)
+    {
+        sec[1] = 0xff;
+        sec[2] = 0xff;
+    }
+    if(bpb->fat_type == FATTYPE_FAT16)
+    {
+        sec[0] = bpb->bpb_media;
+        sec[1] = 0xff;
+        sec[2] = 0xff;
+        sec[3] = 0xff;
+    }
+    secnum++;
+        
+    for(i = 0; i < fatsz - 1;i++)
+    {
+        sec = fat_cache_fat_sector(bpb, secnum);
+        if(!sec)
+        {
+            fprintf(stderr, "fat_create_fat() - Couldn't cache fat sector"
+                    " (%d)\n", i);
+            return -1;
+        }
+        fat_cache_dirty[secnum] = 1;
+        secnum++;
+        memset(sec, 0, BLOCK_SIZE);
+    }
+
+    if(fat_flush_fat(bpb) < 0)
+    {
+        fprintf(stderr, "fat_create_fat() - Couldn't flush fat\n");
+        return -1;
+    }
+    return 0;
+}
+
+int fat_dbg_read_block(char *name, unsigned char *buf)
+{
+    FILE *f;
+
+    f = fopen(name, "rb");
+    if(f)
+    {
+        if(fread(buf, 1, 512, f) != 512)
+        {
+            fprintf(stderr, "Could not read file \"%s\"\n", name);
+            fclose(f);
+            return -1;
+        }
+        /* Now write the sector to disk */
+        ata_write_sectors(0,1,buf);
+        fclose(f);
+    }
+    else
+    {
+        fprintf(stderr, "Could not open file \"%s\"\n", name);
+        return -1;
+    }
+    return 0;
+}
+
+unsigned char *fat_cache_fat_sector(struct bpb *bpb, int secnum)
+{
+    unsigned char *sec;
+
+    sec = fat_cache[secnum];
+    /* Load the sector if it is not cached */
+    if(!sec)
+    {
+        sec = malloc(bpb->bpb_bytspersec);
+        if(!sec)
+        {
+            fprintf(stderr, "fat_cache_fat_sector() - Out of memory\n");
+            return NULL;
+        }
+        if(ata_read_sectors(secnum + bpb->bpb_rsvdseccnt,1,sec))
+        {
+            fprintf(stderr, "fat_cache_fat_sector() - Could"
+                    " not read sector %d\n",
+                    secnum);
+            free(sec);
+            return NULL;
+        }
+        fat_cache[secnum] = sec;
+    }
+    return sec;
+}
+
+int fat_update_entry(struct bpb *bpb, int entry, unsigned int val)
+{
+    unsigned char *sec;
+    unsigned char *sec2;
+    int fatsz;
+    int fatoffset;
+    int thisfatsecnum;
+    int thisfatentoffset;
+    unsigned int tmp;
+
+    fatsz = fat_get_fatsize(bpb);
+    
+    if(bpb->fat_type == FATTYPE_FAT12)
+    {
+        fatoffset = entry + (entry / 2);
+    }
+    else 
+    {
+        if(bpb->fat_type == FATTYPE_FAT16)
+            fatoffset = entry * 2;
+        else
+            fatoffset = entry * 4;
+    }
+    thisfatsecnum = fatoffset / bpb->bpb_bytspersec;
+    thisfatentoffset = fatoffset % bpb->bpb_bytspersec;
+
+    sec = fat_cache_fat_sector(bpb, thisfatsecnum);
+    /* Load the sector if it is not cached */
+    if(!sec)
+    {
+        fprintf(stderr, "fat_update_entry() - Could not cache sector %d\n",
+                thisfatsecnum);
+        return -1;
+    }
+
+    fat_cache_dirty[thisfatsecnum] = 1;
+    
+    switch(bpb->fat_type)
+    {
+        case FATTYPE_FAT12:
+            if(thisfatentoffset == bpb->bpb_bytspersec - 1)
+            {
+                /* This entry spans a sector boundary. Take care */
+                sec2 = fat_cache_fat_sector(bpb, thisfatsecnum + 1);
+                /* Load the sector if it is not cached */
+                if(!sec2)
+                {
+                    fprintf(stderr, "fat_update_entry() - Could not "
+                            "cache sector %d\n",
+                            thisfatsecnum + 1);
+                    return -1;
+                }
+                fat_cache_dirty[thisfatsecnum + 1] = 1;
+            }
+            else
+            {
+                if(entry & 1) /* Odd entry number? */
+                {
+                    tmp = sec[thisfatentoffset] & 0xf0;
+                    sec[thisfatentoffset] = tmp | (val & 0x0f);
+                    sec[thisfatentoffset+1] = (val >> 4) & 0xff;
+                }
+                else
+                {
+                    sec[thisfatentoffset] = val & 0xff;
+                    tmp = sec[thisfatentoffset+1] & 0x0f;
+                    sec[thisfatentoffset+1] = tmp | ((val >> 4) & 0xf0);
+                }
+            }
+            break;
+        case FATTYPE_FAT16:
+            *(unsigned short *)(&sec[thisfatentoffset]) = val;
+            break;
+        case FATTYPE_FAT32:
+            tmp = *(unsigned short *)(&sec[thisfatentoffset]) & 0xf000000;
+            val = tmp | (val & 0x0fffffff);
+            *(unsigned short *)(&sec[thisfatentoffset]) = val;
+            break;
+    }
+    return 0;
+}
+
+int fat_read_entry(struct bpb *bpb, int entry)
+{
+    unsigned char *sec;
+    unsigned char *sec2;
+    int fatsz;
+    int fatoffset;
+    int thisfatsecnum;
+    int thisfatentoffset;
+    int val = -1;
+
+    fatsz = fat_get_fatsize(bpb);
+    
+    if(bpb->fat_type == FATTYPE_FAT12)
+    {
+        fatoffset = entry + (entry / 2);
+    }
+    else 
+    {
+        if(bpb->fat_type == FATTYPE_FAT16)
+            fatoffset = entry * 2;
+        else
+            fatoffset = entry * 4;
+    }
+    thisfatsecnum = fatoffset / bpb->bpb_bytspersec;
+    thisfatentoffset = fatoffset % bpb->bpb_bytspersec;
+
+    sec = fat_cache_fat_sector(bpb, thisfatsecnum);
+    /* Load the sector if it is not cached */
+    if(!sec)
+    {
+        fprintf(stderr, "fat_update_entry() - Could not cache sector %d\n",
+                thisfatsecnum);
+        return -1;
+    }
+
+    switch(bpb->fat_type)
+    {
+        case FATTYPE_FAT12:
+            if(thisfatentoffset == bpb->bpb_bytspersec - 1)
+            {
+                /* This entry spans a sector boundary. Take care */
+                sec2 = fat_cache_fat_sector(bpb, thisfatsecnum + 1);
+                /* Load the sector if it is not cached */
+                if(!sec2)
+                {
+                    fprintf(stderr, "fat_update_entry() - Could not "
+                            "cache sector %d\n",
+                            thisfatsecnum + 1);
+                    return -1;
+                }
+            }
+            else
+            {
+                if(entry & 1) /* Odd entry number? */
+                {
+                    val = (sec[thisfatentoffset] & 0x0f) |
+                        (sec[thisfatentoffset+1] << 4);
+                }
+                else
+                {
+                    val = (sec[thisfatentoffset] & 0xff) |
+                        ((sec[thisfatentoffset+1] & 0x0f) << 8);
+                }
+            }
+            break;
+        case FATTYPE_FAT16:
+            val = *(unsigned short *)(&sec[thisfatentoffset]);
+            break;
+        case FATTYPE_FAT32:
+            val = *(unsigned int *)(&sec[thisfatentoffset]);
+            break;
+    }
+    return val;
+}
+
+int fat_flush_fat(struct bpb *bpb)
+{
+    int i;
+    int err;
+    unsigned char *sec;
+    int fatsz;
+    unsigned short d, t;
+    char m;
+
+    fatsz = fat_get_fatsize(bpb);
+
+    for(i = 0;i < 256;i++)
+    {
+        if(fat_cache[i] && fat_cache_dirty[i])
+        {
+            printf("Flushing FAT sector %d\n", i);
+            sec = fat_cache[i];
+            err = ata_write_sectors(i + bpb->bpb_rsvdseccnt,1,sec);
+            if(err)
+            {
+                fprintf(stderr, "fat_flush_fat() - Couldn't write"
+                        " sector (%d)\n", i + bpb->bpb_rsvdseccnt);
+                return -1;
+            }
+            err = ata_write_sectors(i + bpb->bpb_rsvdseccnt + fatsz,1,sec);
+            if(err)
+            {
+                fprintf(stderr, "fat_flush_fat() - Couldn't write"
+                        " sector (%d)\n", i + bpb->bpb_rsvdseccnt + fatsz);
+                return -1;
+            }
+            fat_cache_dirty[i] = 0;
+        }
+    }
+
+    fat_getcurrdostime(&d, &t, &m);
+    return 0;
+}
+
+unsigned int fat_getcurrdostime(unsigned short *dosdate,
+                                unsigned short *dostime,
+                                unsigned char *dostenth)
+{
+    struct timeb tb;
+    struct tm *tm;
+
+    ftime(&tb);
+    tm = localtime(&tb.time);
+
+    *dosdate = ((tm->tm_year - 80) << 9) |
+        ((tm->tm_mon + 1)  << 5) |
+        (tm->tm_mday);
+
+    *dostime = (tm->tm_hour << 11) |
+        (tm->tm_min << 5) |
+        (tm->tm_sec >> 1);
+
+    *dostenth = (tm->tm_sec & 1) * 100 + tb.millitm / 10;
+    return 0;
+}
+
+int fat_create_root_dir(struct bpb *bpb)
+{
+    unsigned char buf[BLOCK_SIZE];
+    int fatsz;
+    int sec;
+    int res;
+    int i;
+    unsigned short dosdate;
+    unsigned short dostime;
+    unsigned char dostenth;
+    int num_root_sectors;
+
+    fatsz = fat_get_fatsize(bpb);
+
+    sec = bpb->bpb_rsvdseccnt + bpb->bpb_numfats * fatsz;
+
+    memset(buf, 0, sizeof(buf));
+    
+    strncpy(&buf[FATDIR_NAME], bpb->bs_vollab, 11);
+    buf[FATDIR_ATTR] = FAT_ATTR_VOLUME_ID;
+    buf[FATDIR_NTRES] = 0;
+
+    fat_getcurrdostime(&dosdate, &dostime, &dostenth);
+    buf[FATDIR_WRTDATE] = dosdate & 0xff;
+    buf[FATDIR_WRTDATE+1] = dosdate >> 8;
+    buf[FATDIR_WRTTIME] = dostime & 0xff;
+    buf[FATDIR_WRTTIME+1] = dostime >> 8;
+
+    printf("Writing rootdir to sector %d...\n", sec);
+
+    res = ata_write_sectors(sec,1,buf);
+    if(res)
+    {
+        fprintf(stderr, "fat_create_root_dir() - Couldn't write sector (%d)\n",
+                sec);
+        return -1;
+    }
+
+    printf("Clearing the rest of the root dir.\n");
+    sec++;
+    num_root_sectors = bpb->bpb_rootentcnt * 32 / bpb->bpb_bytspersec;
+    memset(buf, 0, BLOCK_SIZE);
+    
+    for(i = 1;i < num_root_sectors;i++)
+    {
+        if(ata_write_sectors(sec++,1,buf))
+        {
+            fprintf(stderr, "fat_create_root_dir() - "
+                            " Couldn't write sector (%d)\n", sec);
+            return -1;
+        }
+    }
+    
+    return 0;
+}
+
+int fat_get_next_cluster(struct bpb *bpb, unsigned int cluster)
+{
+    int next_cluster = fat_read_entry(bpb, cluster);
+
+    if(fat_last_cluster_in_chain(bpb, next_cluster))
+        return 0;
+    else
+        return next_cluster;
+}
+
+int fat_add_dir_entry(struct bpb *bpb, unsigned int currdir,
+                      struct fat_direntry *de)
+{
+    unsigned char buf[BLOCK_SIZE];
+    unsigned char *eptr;
+    int i;
+    int err;
+    unsigned int sec;
+    unsigned int sec_cnt;
+    int need_to_update_last_empty_marker = 0;
+    int is_rootdir = (currdir == 0);
+    int done = 0;
+    unsigned char firstbyte;
+
+    if(is_rootdir)
+    {
+        sec = fat_get_rootdir_sector(bpb);
+    }
+    else
+    {
+        sec = fat_first_sector_of_cluster(bpb, currdir);
+    }
+
+    sec_cnt = 0;
+
+    while(!done)
+    {
+        /* The root dir has a fixed size */
+        if(is_rootdir)
+        {
+            if(sec_cnt >= bpb->bpb_rootentcnt * 32 / bpb->bpb_bytspersec)
+            {
+                /* We have reached the last sector of the root dir */
+                if(need_to_update_last_empty_marker)
+                {
+                    /* Since the directory is full, there is no room for
+                       a marker, so we just exit */
+                    return 0;
+                }
+                else
+                {
+                    fprintf(stderr, "fat_add_dir_entry() -"
+                            " Root dir is full\n");
+                    return -1;
+                }
+            }
+        }
+        else
+        {
+            if(sec_cnt >= bpb->bpb_secperclus)
+            {
+                /* We have reached the end of this cluster */
+                printf("Moving to the next cluster...");
+                currdir = fat_get_next_cluster(bpb, currdir);
+                printf("new cluster is %d\n", currdir);
+                
+                if(!currdir)
+                {
+                    /* This was the last in the chain,
+                       we have to allocate a new cluster */
+                    /* TODO */
+                }
+            }
+        }
+
+        printf("Reading sector %d...\n", sec);
+        /* Read the next sector in the current dir */
+        err = ata_read_sectors(sec,1,buf);
+        if(err)
+        {
+            fprintf(stderr, "fat_add_dir_entry() - Couldn't read dir sector"
+                    " (error code %i)\n", err);
+            return -1;
+        }
+
+        if(need_to_update_last_empty_marker)
+        {
+            /* All we need to do is to set the first entry to 0 */
+            printf("Clearing the first entry in sector %d\n", sec);
+            buf[0] = 0;
+            done = 1;
+        }
+        else
+        {
+            /* Look for a free slot */
+            for(i = 0;i < BLOCK_SIZE;i+=32)
+            {
+                firstbyte = buf[i];
+                if(firstbyte == 0xe5 || firstbyte == 0)
+                {
+                    printf("Found free slot at entry %d in sector %d\n",
+                           i/32, sec);
+                    eptr = &buf[i];
+                    memset(eptr, 0, 32);
+                    strncpy(&eptr[FATDIR_NAME], de->name, 11);
+                    eptr[FATDIR_ATTR] = de->attr;
+                    eptr[FATDIR_NTRES] = 0;
+                    
+                    eptr[FATDIR_CRTTIMETENTH] = de->crttimetenth;
+                    eptr[FATDIR_CRTDATE] = de->crtdate & 0xff;
+                    eptr[FATDIR_CRTDATE+1] = de->crtdate >> 8;
+                    eptr[FATDIR_CRTTIME] = de->crttime & 0xff;
+                    eptr[FATDIR_CRTTIME+1] = de->crttime >> 8;
+                    
+                    eptr[FATDIR_WRTDATE] = de->wrtdate & 0xff;
+                    eptr[FATDIR_WRTDATE+1] = de->wrtdate >> 8;
+                    eptr[FATDIR_WRTTIME] = de->wrttime & 0xff;
+                    eptr[FATDIR_WRTTIME+1] = de->wrttime >> 8;
+                    
+                    eptr[FATDIR_FILESIZE] = de->filesize & 0xff;
+                    eptr[FATDIR_FILESIZE+1] = (de->filesize >> 8) & 0xff;
+                    eptr[FATDIR_FILESIZE+2] = (de->filesize >> 16) & 0xff;
+                    eptr[FATDIR_FILESIZE+3] = (de->filesize >> 24) & 0xff;
+                    
+                    /* Advance the last_empty_entry marker */
+                    if(firstbyte == 0)
+                    {
+                        i += 32;
+                        if(i < BLOCK_SIZE)
+                        {
+                            buf[i] = 0;
+                            /* We are done */
+                            done = 1;
+                        }
+                        else
+                        {
+                            /* We must fill in the first entry
+                               in the next sector */
+                            need_to_update_last_empty_marker = 1;
+                        }
+                    }
+
+                    err = ata_write_sectors(sec,1,buf);
+                    if(err)
+                    {
+                        fprintf(stderr, "fat_add_dir_entry() - "
+                                " Couldn't write dir"
+                                " sector (error code %i)\n", err);
+                        return -1;
+                    }
+                    break;
+                }
+            }
+        }
+        sec++;
+        sec_cnt++;
+    }
+
+    return 0;
+}
+
+unsigned char fat_char2dos(unsigned char c)
+{
+    switch(c)
+    {
+        case 0xe5: /* Special kanji character */
+            c = 0x05;
+            break;
+        case 0x22:
+        case 0x2a:
+        case 0x2b:
+        case 0x2c:
+        case 0x2e:
+        case 0x3a:
+        case 0x3b:
+        case 0x3c:
+        case 0x3d:
+        case 0x3e:
+        case 0x3f:
+        case 0x5b:
+        case 0x5c:
+        case 0x5d:
+        case 0x7c:
+            /* Illegal name */
+            c = 0;
+            break;
+                
+        default:
+            if(c < 0x20)
+            {
+                /* Illegal name */
+                c = 0;
+            }
+            break;
+    }
+    return c;
+}
+
+int fat_create_dos_name(unsigned char *name, unsigned char *newname)
+{
+    unsigned char n[12];
+    unsigned char c;
+    int i;
+    char *ext;
+
+    if(strlen(name) > 12)
+    {
+        return -1;
+    }
+
+    strcpy(n, name);
+    
+    ext = strchr(n, '.');
+    if(ext)
+    {
+        *ext++ = 0;
+    }
+
+    /* The file name is either empty, or there was only an extension.
+       In either case it is illegal. */
+    if(n[0] == 0)
+    {
+        return -1;
+    }
+    
+    /* Name part */
+    for(i = 0;n[i] && (i < 8);i++)
+    {
+        c = fat_char2dos(n[i]);
+        if(c)
+        {
+            newname[i] = toupper(c);
+        }
+    }
+    while(i < 8)
+    {
+        newname[i++] = ' ';
+    }
+
+    /* Extension part */
+    for(i = 0;ext && ext[i] && (i < 3);i++)
+    {
+        c = fat_char2dos(ext[i]);
+        if(c)
+        {
+            newname[8+i] = toupper(c);
+        }
+    }
+    while(i < 3)
+    {
+        newname[8+i++] = ' ';
+    }
+    return 0;
+}
+
+int fat_create_dir(struct bpb *bpb, unsigned int currdir, char *name)
+{
+    struct fat_direntry de;
+    int err;
+
+    printf("fat_create_file()\n");
+    memset(&de, 0, sizeof(struct fat_direntry));
+    if(fat_create_dos_name(name, de.name) < 0)
+    {
+        fprintf(stderr, "fat_create_file() - Illegal file name (%s)\n", name);
+        return -1;
+    }
+
+    fat_getcurrdostime(&de.crtdate, &de.crttime, &de.crttimetenth);
+    de.wrtdate = de.crtdate;
+    de.wrttime = de.crttime;
+    de.filesize = 0;
+    de.attr = FAT_ATTR_DIRECTORY;
+    
+    err = fat_add_dir_entry(bpb, currdir, &de);
+    return 0;
+}
+
+int fat_create_file(struct bpb *bpb, unsigned int currdir, char *name)
+{
+    struct fat_direntry de;
+    int err;
+
+    printf("fat_create_file()\n");
+    memset(&de, 0, sizeof(struct fat_direntry));
+    if(fat_create_dos_name(name, de.name) < 0)
+    {
+        fprintf(stderr, "fat_create_file() - Illegal file name (%s)\n", name);
+        return -1;
+    }
+    fat_getcurrdostime(&de.crtdate, &de.crttime, &de.crttimetenth);
+    de.wrtdate = de.crtdate;
+    de.wrttime = de.crttime;
+    de.filesize = 0;
+    
+    err = fat_add_dir_entry(bpb, currdir, &de);
+    return err;
+}
+
+void fat_fill_direntry(struct fat_direntry *de, char *buf)
+{
+    memset(de, 0, sizeof(struct fat_direntry));
+    
+    strncpy(de->name, &buf[FATDIR_NAME], 11);
+    de->attr = buf[FATDIR_ATTR];
+    de->crttimetenth = buf[FATDIR_CRTTIMETENTH];
+    de->crtdate = buf[FATDIR_CRTDATE] | (buf[FATDIR_CRTDATE+1] << 8);
+    de->crttime = buf[FATDIR_CRTTIME] | (buf[FATDIR_CRTTIME+1] << 8);
+    de->wrtdate = buf[FATDIR_WRTDATE] | (buf[FATDIR_WRTDATE+1] << 8);
+    de->wrttime = buf[FATDIR_WRTTIME] | (buf[FATDIR_WRTTIME+1] << 8);
+    
+    de->filesize = buf[FATDIR_FILESIZE] |
+        (buf[FATDIR_FILESIZE+1] << 8) |
+        (buf[FATDIR_FILESIZE+2] << 16) |
+        (buf[FATDIR_FILESIZE+3] << 24);
+}
+
+int fat_opendir(struct bpb *bpb, struct fat_dirent *ent, unsigned int currdir)
+{
+    int is_rootdir = (currdir == 0);
+    unsigned int sec;
+    int err;
+
+    if(is_rootdir)
+    {
+        sec = fat_get_rootdir_sector(bpb);
+    }
+    else
+    {
+        sec = fat_first_sector_of_cluster(bpb, currdir);
+    }
+
+    /* Read the first sector in the current dir */
+    err = ata_read_sectors(sec,1,ent->cached_buf);
+    if(err)
+    {
+        fprintf(stderr, "fat_getfirst() - Couldn't read dir sector"
+                " (error code %i)\n", err);
+        return -1;
+    }
+
+    ent->entry = 0;
+    ent->cached_sec = sec;
+    ent->num_sec = 0;
+    return 0;
+}
+
+int fat_getnext(struct bpb *bpb, struct fat_dirent *ent,
+                 struct fat_direntry *entry)
+{
+    int done = 0;
+    int i;
+    int err;
+    unsigned char firstbyte;
+
+    while(!done)
+    {
+        /* Look for a free slot */
+        for(i = ent->entry;i < BLOCK_SIZE/32;i++)
+        {
+            firstbyte = ent->cached_buf[i*32];
+            if(firstbyte == 0xe5)
+            {
+                continue;
+            }
+
+            if(firstbyte == 0)
+            {
+                return -1;
+            }
+
+            fat_fill_direntry(entry, &ent->cached_buf[i*32]);
+            done = 1;
+            break;
+        }
+
+        /* Next sector? */
+        if(i >= BLOCK_SIZE/32)
+        {
+            ent->num_sec++;
+            ent->cached_sec++;
+            
+            /* Do we need to advance one cluster? */
+            if(ent->num_sec >= bpb->bpb_secperclus)
+            {
+                ent->num_sec = 0;
+                ent->cached_sec = fat_get_next_cluster(
+                    bpb, fat_sec2cluster(bpb, ent->cached_sec));
+                if(!ent->cached_sec)
+                {
+                    printf("End of cluster chain.\n");
+                    return -1;
+                }
+            }
+
+            /* Read the next sector */
+            err = ata_read_sectors(ent->cached_sec,1,ent->cached_buf);
+            if(err)
+            {
+                fprintf(stderr, "fat_getnext() - Couldn't read dir sector"
+                        " (error code %i)\n", err);
+                return -1;
+            }
+
+            i = 0;
+        }
+        else
+        {
+            i++;
+        }
+        ent->entry = i;
+    }
+    return 0;
+}