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#include "fat.h"
#include "ata.h"
#include "panic.h"
#include "drive.h"
#include "mem.h"
#include "util.h"
#define MAX_FAT_DRIVES 16
#define MAX_OPEN_FILES_PER_DRIVE 32
enum {
FA_READ_ONLY = 0x01,
FA_HIDDEN = 0x02,
FA_SYSTEM = 0x04,
FA_LABEL = 0x08,
FA_DIRECTORY = 0x10,
FA_ARCHIVE = 0x20,
FA_LFN = 0x0f
};
struct directory_entry {
uint8_t name[11];
uint8_t attrib;
uint8_t name_case;
uint8_t created_decimal;
uint16_t created_time;
uint16_t created_date;
uint16_t accessed_date;
uint16_t ignore;
uint16_t modified_time;
uint16_t modified_date;
uint16_t first_cluster;
uint32_t length;
} __attribute__ ((packed));
struct fat_info {
//3 bytes jump
uint8_t oem[8];
uint16_t bytes_per_sector;//Assumed to be 512
uint8_t sectors_per_cluster;//Assumed to be 1
uint16_t reserved_sectors;
uint8_t fats;//Only first is used
uint16_t root_entries;
uint16_t sectors;//Assumed not to be 0
uint8_t media_type;
uint16_t sectors_per_fat;
uint16_t sectors_per_track;
uint16_t heads;
uint32_t hidden_sectors;
uint32_t sectors_long;
uint8_t drive_number;
uint8_t reserved;
uint8_t ext_boot_marker;
uint32_t volume_id;
uint8_t label[11];
uint8_t fs_type[8];
} __attribute__ ((packed));
#define CTOS(c, fi) ((fi)->reserved_sectors + (fi)->sectors_per_fat * (fi)->fats + ((fi)->root_entries >> 4) + (c) - 2)
struct fat_drive_info {
struct fat_info *fi;
uint16_t *fat;
struct directory_entry open_files[MAX_OPEN_FILES_PER_DRIVE];
};
struct fat_drive_info infos[MAX_FAT_DRIVES];
uint8_t next_id = 0;
#define FI(n) ((struct fat_info *)(infos[n].fi + 3))
#define FN(n, f) (infos[n].open_files[f - 1])
uint8_t fat_driver_buffer[512];
struct fat_info *next_fi;
void alloc_next_fi() {
if (!((uint32_t)(next_fi = (struct fat_info *)((uint32_t)next_fi + 64)) & 0xfff))
if (!(next_fi = allocate_pages(1)))
panic("Out of memory in FAT driver.");
}
struct drive *cur_drive;
fs_id_t cur_id;
struct directory_entry *cur_dir;
//loads cluster `c`
void load_cluster(uint16_t c, void *to) {
if (c == 0) {
*(uint8_t *)to = 0;
return;
}
uint32_t s = CTOS(c, FI(cur_id));
cur_drive->read_sectors(cur_drive, s, 1, to);
}
uint16_t next_cluster(uint16_t c) {
panic("TODO: compute next sector (or 0 for none)");
}
static inline bool check_fat_names(uint8_t *a, uint8_t *b) {
return (((uint32_t *)a)[0] == ((uint32_t *)b)[0]) &&
(((uint32_t *)a)[1] == ((uint32_t *)b)[1]) &&
(((uint16_t *)a)[8] == ((uint16_t *)b)[8]) &&
(((uint8_t *)a)[10] == ((uint8_t *)b)[10]);
}
//after: cur_dir -> specified entry in root
bool try_locate_root_entry(uint8_t *fat_name) {
uint32_t cur_dir_sect = FI(cur_id)->reserved_sectors + FI(cur_id)->sectors_per_fat * FI(cur_id)->fats - 1;
cur_dir = (struct directory_entry *)(fat_driver_buffer + 512);
while (true) {
if (cur_dir == (struct directory_entry *)(fat_driver_buffer + 512)) {
cur_dir = (struct directory_entry *)fat_driver_buffer;
++cur_dir_sect;
cur_drive->read_sectors(cur_drive, cur_dir_sect, 1, cur_dir);
}
if (!*(uint8_t *)cur_dir)
return false;
if (check_fat_names(cur_dir->name, fat_name))
return true;
else
++cur_dir;
}
}
//before: cur_dir -> entry of dir to search
//after: cur_dir -> specified entry in dir
bool try_locate_entry(uint8_t *fat_name) {
uint16_t cur_dir_cluster = cur_dir->first_cluster;
load_cluster(cur_dir_cluster, fat_driver_buffer);
cur_dir = (struct directory_entry *)fat_driver_buffer;
while (true) {
if (cur_dir == (struct directory_entry *)(fat_driver_buffer + 512)) {
cur_dir = (struct directory_entry *)fat_driver_buffer;
++cur_dir_cluster;
load_cluster(cur_dir_cluster = next_cluster(cur_dir_cluster), fat_driver_buffer);
}
if (!*(uint8_t *)cur_dir)
return false;
if (check_fat_names(cur_dir -> name, fat_name))
return true;
else
++cur_dir;
}
}
drive_file_id_t fat_get_file(struct drive *d, char *path) {
cur_drive = d;
cur_id = d->drive_id;
for (drive_file_id_t n = 1; n != MAX_OPEN_FILES_PER_DRIVE + 1; ++n)
if (!*(uint8_t *)(&FN(d->drive_id, n))) {
panic("TODO: open path at FN(id, n)");
return n;
}
panic("Maximum number of files open reached for FAT drive.");
}
void fat_free_file(struct drive *d, drive_file_id_t fid) {
*(uint8_t *)(&FN(d->drive_id, fid)) = 0;
}
void fat_load_sector(struct drive *d, drive_file_id_t fid, uint32_t sector, void *at) {
cur_drive = d;
cur_id = d->drive_id;
uint16_t c = FN(d->drive_id, fid).first_cluster;
for (uint32_t i = 0; i < sector; ++i)
c = next_cluster(c);
load_cluster(c, at);
}
uint32_t fat_get_free_sectors(struct drive *d) {
panic("TODO: get free sectors of drive");
}
void init_fat() {
next_fi = allocate_pages(1);
}
bool try_fat_init_drive(struct drive *d) {
if (next_id >= MAX_FAT_DRIVES)
panic("Maximum number of FAT drives reached.");
if (!d->read_sectors(d, 0, 1, fat_driver_buffer))
return false;
memcpy(next_fi, fat_driver_buffer + 3, sizeof(struct fat_info));
uint32_t *fs_type_32 = (uint32_t *)next_fi->fs_type;
if ((fs_type_32[0] != ('F' + 'A' * 256 + 'T' + 65536 + '1' * 16777216)) ||
(fs_type_32[1] != ('6' + ' ' * 256 + ' ' + 65536 + ' ' * 16777216)))
return false;
d->fs_type = "FAT16";
d->get_file = &fat_get_file;
d->free_file = &fat_free_file;
d->load_sector = &fat_load_sector;
d->get_free_sectors = &fat_get_free_sectors;
d->fs_id = next_id;
infos[next_id].fi = next_fi;
infos[next_id].fat = allocate_pages(((next_fi->sectors_per_fat - 1) >> 3) + 1);
for (drive_file_id_t i = 0; i < MAX_OPEN_FILES_PER_DRIVE; ++i)
*(uint8_t *)&FN(next_id, i) = 0;
d->read_sectors(d, next_fi->reserved_sectors, next_fi->sectors_per_fat, infos[next_id].fat);
alloc_next_fi();
++next_id;
return true;
}
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