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basic fs type stuff, fat16, removing stack segment and using data segment

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This commit is contained in:
Benji Dial 2020-05-24 21:55:12 -04:00
parent 02f14113cb
commit 021ea9b271
13 changed files with 252 additions and 79 deletions
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1
doc/internal/gdt.txt
View file

@ -1,3 +1,2 @@
0x08: 0x0000.0000 - 0x0007.ffff (code)
0x10: 0x0000.0000 - 0x000f.ffff (data)
0x18: 0x0003.8000 - 0x0003.ffff (stack)

9
doc/internal/mem.txt
View file

@ -1,8 +1,7 @@
0x0001.0000 - 0x0002.5fff: unused
0x0002.6000 - 0x0002.bfff: fat
0x0001.0000 - 0x0001.ffff: unused
0x0002.0000 - 0x0002.7fff: fat
0x0002.8000 - 0x0002.bfff: unused
0x0002.c000 - 0x0002.ffff: file buffers
0x0003.0000 - 0x0003.7fff: kernel
0x0003.8000 - 0x0003.ffff: stack
0x0004.0000 - 0x0007.ffff: unused
0x0008.0000 - 0x000d.9fff: ramd
0x000d.a000 - 0xffff.ffff: unused
0x0004.0000 - 0x000f.ffff: unused

2
makefile
View file

@ -1,6 +1,6 @@
disk: kernel boot
mkdir -p obj out
/sbin/mkfs.fat -C -f 1 -F 12 -n "PORTLAND OS" -R 17 obj/shadow.img 8192
/sbin/mkfs.fat -C -f 1 -F 16 -n "PORTLAND OS" -R 17 -s 1 -S 512 obj/shadow.img 8192
echo -n -e '\xeb\x3c' > obj/jmp.bin
dd if=obj/jmp.bin of=obj/shadow.img obs=2 conv=notrunc
dd if=out/boot.bin of=obj/shadow.img obs=1 seek=62 conv=notrunc

4
src/boot.asm
View file

@ -39,9 +39,8 @@ bits 32
pmode:
mov ax, 0x10
mov ds, ax
mov ax, 0x18
mov ss, ax
mov esp, 0x00008000
mov esp, 0x00040000
xor ebp, ebp
call kernel_segment * 16
@ -57,7 +56,6 @@ gdt:
dq 0x0000_0000_0000_0000
dq 0x00c0_9a00_0000_007f
dq 0x00c0_9200_0000_00ff
dq 0x0040_9203_8000_7fff
.e:
times $$ + 448 - $ db 0

82
src/kernel/fat.c
View file

@ -1,21 +1,87 @@
#include "fat.h"
#include "ata.h"
#include "panic.h"
#include "fs.h"
void load_fat() {
read_sectors(FAT_INFO->reserved_sectors, FAT_INFO->sectors_per_fat, FAT);
}
uint16_t get_cluster(uint16_t n) {
uint32_t t = *(uint32_t *)(FAT + (n / 2) * 3);
return (n % 2 ? (t >> 12) : t) & 0xfff;
bool check_fat_name(uint8_t *fname, uint8_t *sname) {
panic("Not implemented (check_fat_name)");
}
void set_cluster(uint16_t n, uint16_t v) {
uint32_t *t = (uint32_t *)(FAT + (n / 2) * 3);
*t = (*t & (n % 2 ? 0xff000fff : 0xfffff000)) | (n % 2 ? v << 12 : v);
bool check_fat_names(uint8_t *lname, uint8_t *rname) {
return (* (uint32_t *)lname == *(uint32_t *)rname) &&
(*((uint32_t *)lname + 1) == *((uint32_t *)rname + 1)) &&
(*((uint16_t *)lname + 4) == *((uint16_t *)rname + 4)) &&
(*( lname + 10) == *( rname + 10));
}
uint16_t get_start_cluster(uint8_t *path) {
panic("Not implemented (get_start_cluster).");
struct directory_entry buffer[16];
uint16_t dir_start, buffer_from;
void load_root() {
dir_start = FAT_INFO->reserved_sectors + FAT_INFO->sectors_per_fat;
}
struct directory_entry *load_subentry(uint8_t *name) {
struct directory_entry *ptr = buffer;
uint16_t dir_current = dir_start;
do
if (((ptr == buffer + 16) && !read_sectors(buffer_from = dir_current++, 1, ptr = buffer)) || !ptr->name[0])
return 0;
while (!check_fat_name(ptr->name, name));
return ptr;
}
bool load_subdir(uint8_t *name) {
struct directory_entry *e = load_subentry(name);
if (!e)
return true;
dir_start = e->first_cluster;
return false;
}
struct directory_entry *load_entry(uint8_t *path) {
load_root();
for (uint8_t *ptr = path; ptr; ++ptr)
if (*ptr = '/') {
*ptr = 0;
if (load_subdir(path))
return 0;
path = ptr + 1;
}
return load_subentry(path);
}
bool get_entry(uint8_t *path, struct directory_entry *at) {
struct directory_entry *e = load_entry(path);
if (!e)
return true;
*at = *e;
return false;
}
bool update_entry(uint8_t *path, struct directory_entry *value) {
struct directory_entry *e = load_entry(path);
if (!e)
return true;
*e = *value;
write_sectors(buffer_from, 1, buffer);
return false;
}
bool create_entry(uint8_t *dir_path, struct directory_entry *value) {
fs_handle h = fs_open(dir_path);
struct directory_entry *check;
while (fs_read(h, 32, check))
if (check_fat_names(check->name, value->name)) {
fs_close(h);
return true;
}
fs_write(h, 32, value);
fs_close(h);
return false;
}

39
src/kernel/fat.h
View file

@ -1,4 +1,5 @@
#include <stdint.h>
#include <stdbool.h>
#define FAT_INFO ((struct fat_info *)0x7c03)
@ -24,9 +25,37 @@ struct fat_info {
uint8_t fs_type[8];
} __attribute__ ((packed));
#define FAT ((void *)0x00026000)
void load_fat();
uint16_t get_cluster(uint16_t n);
void set_cluster(uint16_t n, uint16_t v);
enum {
FA_READ_ONLY = 0x01,
FA_HIDDEN = 0x02,
FA_SYSTEM = 0x04,
FA_LABEL = 0x08,
FA_DIRECTORY = 0x10,
FA_ARCHIVE = 0x20,
uint16_t get_start_cluster(uint8_t *path);
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));
#define FAT ((uint16_t *)0x00020000)
void load_fat();
#define CTOS(c) (FAT_INFO->reserved_sectors + FAT_INFO->sectors_per_fat + (FAT_INFO->root_entries >> 4) + (c) - 2)
bool get_entry(uint8_t *path, struct directory_entry *at);
bool update_entry(uint8_t *path, struct directory_entry *value);
bool create_entry(uint8_t *path, struct directory_entry *value);

106
src/kernel/fs.c
View file

@ -4,17 +4,26 @@
#include "fat.h"
#include <stdbool.h>
#include "panic.h"
#include "util.h"
#define MAX_HANDLES 32
#define FILE_BUFFER(h) ((void *)(0x0002be00 + (h << 9)))
#define HANDLE(h) ((handles - 1)[h])
#define HEAD(h) (FILE_BUFFER(h) + HANDLE(h).seek % 512)
enum {
FH_DIRTY = 0x01,
FH_NO_WRITE = 0x02,
FH_NO_EXPAND = 0x04,
FH_ROOT = 0x08
};
struct handle_info {
uint16_t start_cluster;
uint16_t seek;
uint16_t first_cluster;
uint16_t loaded_cluster;
bool dirty;
uint32_t seek;
uint32_t length;
uint8_t flags;
};
struct handle_info handles[MAX_HANDLES];
@ -22,61 +31,114 @@ struct handle_info handles[MAX_HANDLES];
void clear_fs_handles() {
struct handle_info *f = handles;
while (f < handles + MAX_HANDLES)
(f++)->start_cluster = 0;
(f++)->first_cluster = 0;
}
fs_handle next_handle() {
fs_handle r = 0;
while (HANDLE(++r).start_cluster)
while (HANDLE(++r).first_cluster)
if (r == MAX_HANDLES)
return 0;
return r;
}
void write_buffer(fs_handle handle) {
HANDLE(handle).dirty = false;
panic("Not implemented (write_buffer).");
HANDLE(handle).flags &= ~FH_DIRTY;
if (HANDLE(handle).flags & FH_ROOT)
write_sectors(HANDLE(handle).loaded_cluster, 1, FILE_BUFFER(handle));
else
write_sectors(CTOS(HANDLE(handle).loaded_cluster), 1, FILE_BUFFER(handle));
}
void read_buffer(fs_handle handle) {
if (HANDLE(handle).dirty)
if (HANDLE(handle).flags & FH_DIRTY)
write_buffer(handle);
HANDLE(handle).loaded_cluster = HANDLE(handle).seek >> 9;
panic("Not implemented (read_buffer).");
uint16_t s = HANDLE(handle).seek >> 9;
if (HANDLE(handle).flags & FH_ROOT) {
HANDLE(handle).loaded_cluster = HANDLE(handle).first_cluster + s;
read_sectors(HANDLE(handle).first_cluster + s, 1, FILE_BUFFER(handle));
}
else {
uint16_t c = HANDLE(handle).first_cluster;
while (s--)
c = FAT[c];
HANDLE(handle).loaded_cluster = c;
read_sectors(CTOS(c), 1, FILE_BUFFER(handle));
}
}
fs_handle fs_open(uint8_t *path) {
fs_handle next = next_handle();
if (!next)
return 0;
uint16_t s = get_start_cluster(path);
if (!s)
struct directory_entry e;
if (get_entry(path, &e))
return 0;
HANDLE(next).start_cluster = s;
HANDLE(next).first_cluster = e.first_cluster;
HANDLE(next).seek = 0;
HANDLE(next).dirty = false;
HANDLE(next).length = e.length;
HANDLE(next).flags = (e.attrib & FA_READ_ONLY ? FH_NO_WRITE : 0) |
(e.attrib & FA_SYSTEM ? FH_NO_EXPAND : 0);
read_buffer(next);
return next;
}
int16_t fs_seek(fs_handle handle, int16_t by) {
uint16_t old = HANDLE(handle).seek;
uint16_t to = -by > old ? 0 : old + by;
fs_handle fs_open_root() {
fs_handle next = next_handle();
if (!next)
return 0;
HANDLE(next).first_cluster = FAT_INFO->reserved_sectors + FAT_INFO->sectors_per_fat;
HANDLE(next).seek = 0;
HANDLE(next).length = FAT_INFO->root_entries * 32;
HANDLE(next).flags = FH_NO_EXPAND | FH_ROOT;
read_buffer(next);
return next;
}
int32_t fs_seek(fs_handle handle, int32_t by) {
uint32_t old = HANDLE(handle).seek;
uint32_t to = -by > old ? 0 : old + by > HANDLE(handle).length ? HANDLE(handle).length : old + by;
HANDLE(handle).seek = to;
if ((to ^ old) & 0xfe00)
read_buffer(handle);
return to - old;
}
uint16_t fs_read(fs_handle handle, uint16_t max, void *buffer) {
panic("Not implemented (fs_read).");
uint32_t fs_read(fs_handle handle, uint32_t max, void *buffer) {
max = HANDLE(handle).seek + max > HANDLE(handle).length ? HANDLE(handle).length - HANDLE(handle).seek : max;
uint32_t left = max, eos = 512 - (HANDLE(handle).seek & 0x1ff);
if (left < eos) {
memcpy(buffer, FILE_BUFFER(handle) + (HANDLE(handle).seek & 0x1ff), left);
HANDLE(handle).seek += left;
return max;
}
memcpy(buffer, FILE_BUFFER(handle) + (HANDLE(handle).seek & 0x1ff), eos);
left -= eos;
buffer += eos;
HANDLE(handle).seek += eos;
while (left >= 512) {
read_buffer(handle);
memcpy(buffer, FILE_BUFFER(handle), 512);
left -= 512;
buffer += 512;
HANDLE(handle).seek += 512;
}
if (left) {
read_buffer(handle);
memcpy(buffer, FILE_BUFFER(handle), left);
HANDLE(handle).seek += left;
}
return max;
}
uint16_t fs_write(fs_handle handle, uint16_t max, void *buffer) {
uint32_t fs_write(fs_handle handle, uint32_t max, void *buffer) {
if (HANDLE(handle).flags & FH_NO_WRITE)
return 0;
panic("Not implemented (fs_write).");
}
void fs_close(fs_handle handle) {
if (HANDLE(handle).dirty)
if (HANDLE(handle).flags & FH_DIRTY)
write_buffer(handle);
HANDLE(handle).start_cluster = 0;
HANDLE(handle).first_cluster = 0;
}

7
src/kernel/fs.h
View file

@ -4,7 +4,8 @@ void clear_fs_handles();
typedef uint8_t fs_handle;
fs_handle fs_open(uint8_t *path);
int16_t fs_seek(fs_handle handle, int16_t by);
uint16_t fs_read(fs_handle handle, uint16_t max, void *buffer);
uint16_t fs_write(fs_handle handle, uint16_t max, void *buffer);
fs_handle fs_open_root();
int32_t fs_seek(fs_handle handle, int32_t by);
uint32_t fs_read(fs_handle handle, uint32_t max, void *buffer);
uint32_t fs_write(fs_handle handle, uint32_t max, void *buffer);
void fs_close(fs_handle handle);

44
src/kernel/main.c
View file

@ -16,21 +16,43 @@ void main() {
vga_printsz("\n Serial ready.");
load_fat();
clear_fs_handles();
vga_printsz("\n File system ready.\n\nDisk label: ");
vga_printsz("\n File system ready.\n\nDisk info:\n Disk label: ");
vga_printsn(FAT_INFO->label, 11);
vga_printsz("\n Disk size: ");
u32_dec(FAT_INFO->sectors >> 1, nbuf);
u16_dec(FAT_INFO->sectors >> 1, nbuf);
vga_printsz(nbuf);
vga_printsz("k\n\nFAT start:\n");
vga_printsz("k\n FAT size: ");
u16_dec(FAT_INFO->sectors_per_fat >> 1, nbuf);
vga_printsz(nbuf);
vga_printsz("k\n Root size: ");
u16_dec(FAT_INFO->root_entries >> 5, nbuf);
vga_printsz(nbuf);
vga_printsz("k\n\nRoot directory:");
fs_handle root = fs_open_root();
struct directory_entry e;
while(1) {
fs_read(root, 32, &e);
if (!e.name[0])
break;
if (e.attrib == FA_LFN)
continue;
uint8_t *p = (uint8_t *)&e;
nbuf[3] = 0;
for (uint8_t r = 0; r < 192; r += 24) {
for (uint8_t c = 0; c < 24; ++c) {
u8_hex(*(uint8_t *)(FAT + r + c), nbuf);
nbuf[2] = ' ';
vga_printsz("\n ");
vga_printsn((uint8_t *)&e.name, 11);
vga_printsz(" | 0x");
u8_hex(e.attrib, nbuf);
vga_printsz(nbuf);
vga_printch(' ');
vga_printch(e.attrib & FA_READ_ONLY ? 'R' : '_');
vga_printch(e.attrib & FA_HIDDEN ? 'H' : '_');
vga_printch(e.attrib & FA_SYSTEM ? 'S' : '_');
vga_printch(e.attrib & FA_LABEL ? 'L' : '_');
vga_printch(e.attrib & FA_DIRECTORY ? 'D' : '_');
vga_printch(e.attrib & FA_ARCHIVE ? 'A' : '_');
vga_printsz(" | ");
u32_dec(e.length, nbuf);
vga_printsz(nbuf);
}
vga_printch('\n');
}
while (1)
asm ("hlt");
halt();
}

5
src/kernel/panic.c
View file

@ -4,6 +4,7 @@
#include "util.h"
void halt() {
vga_printsz("\n\nHalting...");
while (1)
asm volatile ("hlt");
}
@ -20,12 +21,12 @@ void panic(uint8_t *message) {
vga_printsz("\n\nStack trace:");
uint8_t stb[6];
while (1) {
uint32_t ip = *(uint32_t *)(0x38000 + frame + 4);
uint32_t ip = *((uint32_t *)frame + 1);
if (!ip)
halt();
vga_printsz("\n 0x");
u16_hex(ip - 0x30000 - 5, stb);//assumes would return to just after a call instruction
vga_printsz(stb);
frame = *(uint32_t *)(0x38000 + frame);
frame = *(uint32_t *)frame;
}
}

11
src/kernel/util.c
View file

@ -2,8 +2,15 @@
#include "panic.h"
#include <stdbool.h>
void memcpy(void *from, void *to, uint32_t n) {
panic("Not implemented (memcpy).");
void memcpy(void *to, void *from, uint32_t n) {
uint32_t *tp = to, *fp = from;
while (n >= 4) {
*(tp++) = *(fp++);
n -= 4;
}
uint8_t *tpp = (uint8_t *)tp, *fpp = (uint8_t *)fp;
while (n--)
*(tpp++) = *(fpp++);
}
void u32_dec(uint32_t n, uint8_t *b) {

2
src/kernel/util.h
View file

@ -1,6 +1,6 @@
#include <stdint.h>
void memcpy(void *from, void *to, uint32_t n);
void memcpy(void *to, void *from, uint32_t n);
void outb(uint16_t port, uint8_t value);
uint8_t inb(uint16_t port);
void outw(uint16_t port, uint16_t value);

11
src/kernel/vga.inc
View file

@ -1,11 +0,0 @@
extern vga_set_color
extern vga_blank
extern vga_scroll
extern vga_printch
extern vga_printsz
extern vga_printsn
extern vga_printu32
extern vga_printu16
extern vga_printu8
extern vga_printu32h
extern vga_printu8h