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/*
fat.c (09.11.10)
File Allocation Table creation code.
Free exFAT implementation.
Copyright (C) 2011-2015 Andrew Nayenko
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.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "fat.h"
#include "cbm.h"
#include "uct.h"
#include "rootdir.h"
#include <unistd.h>
static off_t fat_alignment(void)
{
return (off_t) 128 * get_sector_size();
}
static off_t fat_size(void)
{
return get_volume_size() / get_cluster_size() * sizeof(cluster_t);
}
static cluster_t fat_write_entry(struct exfat_dev* dev, cluster_t cluster,
cluster_t value)
{
le32_t fat_entry = cpu_to_le32(value);
if (exfat_write(dev, &fat_entry, sizeof(fat_entry)) < 0)
{
exfat_error("failed to write FAT entry 0x%x", value);
return 0;
}
return cluster + 1;
}
static cluster_t fat_write_entries(struct exfat_dev* dev, cluster_t cluster,
uint64_t length)
{
cluster_t end = cluster + DIV_ROUND_UP(length, get_cluster_size());
while (cluster < end - 1)
{
cluster = fat_write_entry(dev, cluster, cluster + 1);
if (cluster == 0)
return 0;
}
return fat_write_entry(dev, cluster, EXFAT_CLUSTER_END);
}
static int fat_write(struct exfat_dev* dev)
{
cluster_t c = 0;
if (!(c = fat_write_entry(dev, c, 0xfffffff8))) /* media type */
return 1;
if (!(c = fat_write_entry(dev, c, 0xffffffff))) /* some weird constant */
return 1;
if (!(c = fat_write_entries(dev, c, cbm.get_size())))
return 1;
if (!(c = fat_write_entries(dev, c, uct.get_size())))
return 1;
if (!(c = fat_write_entries(dev, c, rootdir.get_size())))
return 1;
return 0;
}
const struct fs_object fat =
{
.get_alignment = fat_alignment,
.get_size = fat_size,
.write = fat_write,
};
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