Independent ext2 bootloader for bigger kernels

3 files changed, 846 insertions, 0 deletions

diff --git a/boot/Makefile b/boot/Makefile
new file mode 100644
index 0000000..44743d7
--- /dev/null
+++ b/boot/Makefile
@@ -0,0 +1,18 @@
+# MIT License, Copyright (c) 2020 Marvin Borner
+
+CC = ../cross/opt/bin/i686-elf-gcc
+LD = ../cross/opt/bin/i686-elf-ld
+OC = ../cross/opt/bin/i686-elf-objcopy
+AS = nasm
+
+CFLAGS = -Wall -Wextra -nostdlib -nostdinc -ffreestanding -ffunction-sections -fno-builtin -std=c99 -m32 -pedantic-errors
+
+ASFLAGS = -f elf32
+
+all: compile
+
+compile:
+	@mkdir -p ../build/
+	@$(CC) -c $(CFLAGS) load.c -o load.o
+	@$(LD) -N -emain -Ttext 0x00040000 -o ../build/load.bin load.o --oformat binary
+	@$(AS) -f bin entry.asm -o ../build/boot.bin
diff --git a/boot/entry.asm b/boot/entry.asm
new file mode 100644
index 0000000..c6b36f0
--- /dev/null
+++ b/boot/entry.asm
@@ -0,0 +1,436 @@
+; Melvin's awesome ext2 bootloader
+; I'm not really good at assembly, there are MANY ways to improve this!
+; MIT License, Copyright (c) 2020 Marvin Borner
+
+; Definitions
+
+; General configurations
+; TODO: Find out why 2560x1600 doesn't work
+%define VIDEO_WIDTH 1920
+%define VIDEO_HEIGHT 1200
+%define VIDEO_BPP 4
+
+; Boot constants
+%define LOCATION 0x7c00 ; Bootloader location
+%define SECTOR_END 0xaa55 ; Bootsector end signature
+%define SECTOR_SIZE 510 ; 512 bytes minus signature
+
+; Interrupts
+%define VIDEO_INT 0x10 ; Video BIOS Interrupt
+%define DISK_INT 0x13 ; Disk BIOS Interrupt
+%define MISC_INT 0x15 ; Miscellaneous services BIOS Interrupt
+
+; Characters
+%define NEWLINE 0x0A ; Newline character (\n)
+%define RETURN 0x0D ; Return character (\r)
+%define NULL 0x00 ; NULL character (\0)
+
+; Video commands (VGA)
+%define VIDEO_CLEAR 0x03 ; Clear screen command
+%define VIDEO_OUT 0x0e ; Teletype output command
+
+; Disk commands
+%define DISK_EXT_CHECK 0x41 ; Disk extension check command
+%define DISK_EXT_CHECK_SIG1 0x55aa ; First extension check signature
+%define DISK_EXT_CHECK_SIG2 0xaa55 ; Second extension check signature
+%define DISK_ZERO 0x80 ; First disk - TODO: Disk detection
+%define DISK_READ 0x42 ; Disk extended read command
+
+; EXT2 constants
+%define EXT2_SB_SIZE 0x400 ; Superblock size
+%define EXT2_SIG_OFFSET 0x38 ; Signature offset in superblock
+%define EXT2_TABLE_OFFSET 0x08 ; Inode table offset after superblock
+%define EXT2_INODE_TABLE_LOC 0x1000 ; New inode table location in memory
+%define EXT2_KERNEL_INODE 0x05 ; Kernel inode
+%define EXT2_INODE_SIZE 0x80 ; Single inode size
+%define EXT2_GET_ADDRESS(inode) (EXT2_INODE_TABLE_LOC + (inode - 1) * EXT2_INODE_SIZE)
+%define EXT2_COUNT_OFFSET 0x1c ; Inode offset of number of data blocks
+%define EXT2_POINTER_OFFSET 0x28 ; Inode offset of first data pointer
+%define EXT2_IND_POINTER_OFFSET 0x2c ; Inode offset of singly indirect data pointer
+%define EXT2_DIRECT_POINTER_COUNT 0x0c ; Direct pointer count
+%define EXT2_SIG 0xef53 ; Signature
+
+; Video constants (VESA)
+%define VESA_START 0x2000 ; Struct starts at 0x2000
+%define VESA_END 0x3000 ; Struct ends at 0x3000
+%define VESA_GET_MODES 0x4f00 ; Get video modes (via 10h)
+%define VESA_GET_INFO 0x4f01 ; Get video mode info (via 10h)
+%define VESA_SET_MODE 0x4f02 ; Set video mode (via 10h)
+%define VESA_SUCCESS_SIG 0x004f ; Returns if VBE call succeeded
+%define VESA_MODE_OFFSET 0xe ; Offset to mode pointer
+%define VESA_MODE_SEGMENT 0x10 ; Mode pointer segment
+%define VESA_LIST_END 0xffff ; End of mode list
+%define VESA_PITCH_OFFSET 0x10 ; Pitch offset in mode info
+%define VESA_WIDTH_OFFSET 0x12 ; Width offset in mode info
+%define VESA_HEIGHT_OFFSET 0x14 ; Height offset in mode info
+%define VESA_BPP_OFFSET 0x19 ; Bytes Per Pixel (BPP) offset in mode info
+%define VESA_FRAMEBUFFER_OFFSET 0x2a ; Framebuffer offset in mode info
+%define VESA_LFB_FLAG 0x4000 ; Enable LFB flag
+
+; A20 constants
+%define A20_GATE 0x92 ; Fast A20 gate
+%define A20_ENABLED 0b10 ; Bit 1 defines whether A20 is enabled
+%define A20_EXCLUDE_BIT 0xfe ; Bit 0 may be write-only, causing a crash
+
+; GDT constants (bitmap)
+%define GDT_MAX_LIMIT 0xffff ; I just use the max limit lel
+%define GDT_PRESENT 0b10000000 ; Is present
+%define GDT_RING3 0b01100000 ; Privilege level 3
+%define GDT_DESCRIPTOR 0b00010000 ; Descriptor type, set for code/data
+%define GDT_EXECUTABLE 0b00001000 ; Can be executed
+%define GDT_READWRITE 0b00000010 ; Read/write access for code/data
+%define GDT_ACCESSED 0b00000001 ; Whether segment is accessed
+%define GDT_GRANULARITY (0x80 | 0x00) ; Page granularity (4KiB)
+%define GDT_SIZE (0x40 | 0x00) ; Use 32 bit selectors
+%define GDT_DATA_OFFSET 0x10 ; Offset to GDT data segment
+
+; Kernel constants
+%define STACK_POINTER 0x00900000 ; The initial stack pointer in kernel mode
+%define KERNEL_POSITION 0x00040000 ; Loaded kernel position in protected mode (* 0x10)
+
+; ENOUGH, let's go!
+
+bits 16
+org LOCATION
+
+; This is the first stage. It prints some things, checks some things
+; and jumps to the second stage. Nothing special.
+global _start
+_start:
+	; Clear screen
+	mov ax, VIDEO_CLEAR
+	int VIDEO_INT
+
+	; Check LBA support
+	mov ah, DISK_EXT_CHECK
+	mov bx, DISK_EXT_CHECK_SIG1
+	int DISK_INT
+	jc lba_error
+	cmp bx, DISK_EXT_CHECK_SIG2
+	jnz lba_error
+
+	; Check disk and move dl
+	and dl, DISK_ZERO ; Use disk 0
+	jz disk_error
+	mov [drive], dl
+
+	; Load stage two
+	mov bx, stage_two
+	mov [dest], bx
+	call disk_read
+
+	; JUMP
+	jmp stage_two
+
+print:
+	push bx
+	push ax
+	mov ah, VIDEO_OUT
+	xor bh, bh
+	print_ch:
+		lodsb
+		test al, al
+		jz print_end
+		int VIDEO_INT
+		jmp print_ch
+	print_end:
+	pop ax
+	pop bx
+	ret
+
+disk_read:
+	mov si, packet ; Address of dap
+	mov ah, DISK_READ ; Extended read
+	mov dl, [drive] ; Drive number
+	int DISK_INT
+	jc disk_error
+	ret
+
+; Errors
+disk_error:
+	mov si, disk_error_msg
+	call print
+	jmp $
+lba_error:
+	mov si, lba_error_msg
+	call print
+	jmp $
+
+; Now put some data and routines just before the end of the boot sector because
+; we've still got some space left :)
+
+; Video map routine
+video_map:
+	mov bx, VESA_START ; Set load address
+	mov di, bx
+	mov ax, VESA_GET_MODES ; Get video modes
+	int VIDEO_INT ; Ask BIOS for data!
+
+	cmp ax, VESA_SUCCESS_SIG ; Check VBE support in response
+	jne .error ; Not supported :(
+
+	mov si, [bx + VESA_MODE_OFFSET] ; Mode pointer offset
+	mov ax, [bx + VESA_MODE_SEGMENT] ; Mode pointer segment
+	mov es, ax
+
+	mov di, VESA_END ; End of VBE struct
+.loop:
+	mov bx, [es:si] ; Load bx with video mode
+	cmp bx, VESA_LIST_END ; Is this the end?
+	jae .done ; Yes, there aren't any modes left
+
+	add si, 2
+	mov [.mode], bx
+
+	mov ax, VESA_GET_INFO ; Get mode information
+	mov cx, [.mode] ; Save in here
+	int VIDEO_INT ; BIOS interrupt!
+	cmp ax, VESA_SUCCESS_SIG ; Check if call succeeded
+	jne .error ; Nope, jump to error!
+
+	mov ax, [es:di + VESA_FRAMEBUFFER_OFFSET] ; Save framebuffer
+	mov [.framebuffer], ax ; Move fb address to struct
+
+	mov ax, [es:di + VESA_PITCH_OFFSET] ; Save pitch
+	mov bx, [es:di + VESA_WIDTH_OFFSET] ; Save width
+	mov cx, [es:di + VESA_HEIGHT_OFFSET] ; Save height
+	mov dx, [es:di + VESA_BPP_OFFSET] ; Save BPP
+
+	mov [.bpp], dx ; Move bpp to struct (bigger bpp is always desired)
+	add di, 0x100
+
+	cmp ax, [.pitch] ; Compare with desired pitch
+	jne .loop ; Not equal, continue search!
+	cmp bx, [.width] ; Compare with desired height
+	jne .loop ; Not equal, continue search!
+	cmp cx, [.height] ; Compare with desired height
+	jne .loop ; Not equal, continue search!
+
+	lea ax, [es:di - 0x100]
+	mov [vid_info.array], ax
+.set_mode:
+	mov ax, VESA_SET_MODE ; Set VBE mode
+	mov bx, [.mode] ; Set mode address
+	mov [vid_info], bx ; Move mode information to array
+	or bx, VESA_LFB_FLAG ; Enable LFB
+	int VIDEO_INT ; SET!
+	cmp ax, VESA_SUCCESS_SIG ; Check if set succeeded
+	jne .error ; Nope, jump to error!
+.done:
+	ret ; Finished loop and set!
+.error: ; Something failed - print message and loop!
+	mov si, video_error_msg
+	call print
+	jmp $
+
+; Video default data
+.mode dw 0
+.width dw VIDEO_WIDTH
+.height dw VIDEO_HEIGHT
+.pitch dw (VIDEO_WIDTH * VIDEO_BPP)
+.bpp dw VIDEO_BPP
+.framebuffer dd 0
+
+; Variables
+disk_error_msg db "Disk error!", NEWLINE, RETURN, NULL
+lba_error_msg db "LBA error!", NEWLINE, RETURN, NULL
+video_error_msg db "Video error!", NEWLINE, RETURN, NULL
+drive db 0
+
+; Video info struct
+vid_info:
+.mode dd 0 ; Mode info pointer
+.array dd 0 ; Mode array pointer
+
+; Data
+packet:
+	db 0x10 ; Packet size
+	db 0 ; Always 0
+count:
+	dw 4 ; Number of sectors to transfer
+dest:
+	dw 0 ; Destination offset
+	dw 0 ; Destination segment
+lba:
+	dd 1 ; LBA number
+	dd 0 ; More storage bytes
+
+; End of boot sector
+times SECTOR_SIZE - ($ - $$) db 0
+dw SECTOR_END
+
+; This is the second stage. It tries to load the kernel (inode 5) into memory.
+; To do this, it first checks the integrity of the ext2 fs. Then it has to find
+; the address of the fifth inode and load its contents into memory.
+; After this is finished, the stage can jump into the protected mode, enable the
+; A20 line and finally jump to the kernel! ez
+stage_two:
+	; Verify signature
+	mov ax, [superblock + EXT2_SIG_OFFSET]
+	cmp ax, EXT2_SIG
+	jne disk_error
+
+	; Load inode table
+	mov ax, [superblock + EXT2_SB_SIZE + EXT2_TABLE_OFFSET] ; Inode table
+	shl ax, 1 ; Multiply ax by 2
+	mov [lba], ax ; Sector
+	mov ax, 2
+	mov [count], ax ; Read 1024 bytes
+	mov bx, EXT2_INODE_TABLE_LOC ; Copy data to 0x1000
+	mov [dest], bx
+	call disk_read
+
+	; Load kernel
+	mov bx, EXT2_GET_ADDRESS(EXT2_KERNEL_INODE) ; First block
+	mov cx, [bx + EXT2_COUNT_OFFSET] ; Number of blocks for inode
+	lea di, [bx + EXT2_POINTER_OFFSET] ; Address of first block pointer
+	mov bx, 0x4000 ; Load to this address
+	mov [dest + 2], bx
+	mov bx, 0 ; Inode location = 0xF0000
+	mov [dest], bx
+	call kernel_load
+
+	; Set video mode
+	call video_map
+
+	jmp protected_mode_enter
+
+kernel_load:
+	mov ax, [di] ; Set ax = block pointer
+	shl ax, 1 ; Multiply ax by 2
+	mov [lba], ax
+	mov [dest], bx
+	call disk_read
+	jmp .end
+
+.end:
+	add bx, 0x400 ; 1kb increase
+	add di, 0x4 ; Move to next block pointer
+	sub cx, 0x2 ; Read 2 blocks
+	jnz kernel_load
+	ret
+
+protected_mode_enter:
+	cli ; Turn off interrupts
+
+	; TODO: Check A20 support?
+	; TODO: 0x92 method may not work on every device
+	in al, A20_GATE
+	test al, A20_ENABLED
+	jnz .a20_enabled
+	or al, A20_ENABLED
+	and al, A20_EXCLUDE_BIT
+	out A20_GATE, al
+	.a20_enabled:
+
+	lgdt [gdt_desc] ; Load GDT
+
+	; Set protected mode via cr0
+	mov eax, cr0
+	or eax, 1 ; Set bit 0
+	mov cr0, eax
+
+	jmp (gdt_code - gdt):protected_mode ; JUMP!
+
+bits 32 ; Woah, so big!
+protected_mode:
+	mov ax, GDT_DATA_OFFSET ; Data segment offset of GDT
+	mov ds, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+	mov ss, ax ; Stack segment
+
+	mov esp, STACK_POINTER ; Move stack pointer
+
+	mov ax, (gdt_tss - gdt) | 0b11 ; Load TSS in ring 3
+	ltr ax
+
+	mov eax, vid_info ; Pass VBE struct to kernel
+	push eax ; Push as second kernel parameter
+
+	mov edx, KERNEL_POSITION
+	lea eax, [edx]
+	call eax
+
+; GDT
+align 32
+gdt: ; GDTs start
+gdt_null: ; Must be null
+	dd 0
+	dd 0
+gdt_code: ; Code segment
+	dw GDT_MAX_LIMIT ; Limit
+	dw 0 ; First base
+	db 0 ; Second base
+	db (GDT_PRESENT | GDT_DESCRIPTOR | GDT_EXECUTABLE | GDT_READWRITE) ; Configuration
+	db (GDT_GRANULARITY | GDT_SIZE) ; Flags
+	db 0 ; Third base
+gdt_data: ; Data segment
+	dw GDT_MAX_LIMIT ; Limit
+	dw 0 ; First base
+	db 0 ; Second base
+	db (GDT_PRESENT | GDT_DESCRIPTOR | GDT_READWRITE) ; Configuration
+	db (GDT_GRANULARITY | GDT_SIZE) ; Flags
+	db 0 ; Third base
+gdt_user_code: ; User code segment
+	dw GDT_MAX_LIMIT ; Limit
+	dw 0 ; First base
+	db 0 ; Second base
+	db (GDT_PRESENT | GDT_RING3 | GDT_DESCRIPTOR | GDT_EXECUTABLE | GDT_READWRITE) ; Configuration
+	db (GDT_GRANULARITY | GDT_SIZE) ; Flags
+	db 0 ; Third base
+gdt_user_data: ; Data segment
+	dw GDT_MAX_LIMIT ; Limit
+	dw 0 ; First base
+	db 0 ; Second base
+	db (GDT_PRESENT | GDT_RING3 | GDT_DESCRIPTOR | GDT_READWRITE) ; Configuration
+	db (GDT_GRANULARITY | GDT_SIZE) ; Flags
+	db 0 ; Third base
+gdt_tss: ; TSS segment
+	dw tss_entry + (tss_entry_end - tss_entry) ; Limit
+	dw tss_entry ; First base
+	db 0 ; Second base
+	db (GDT_PRESENT | GDT_RING3 | GDT_EXECUTABLE | GDT_ACCESSED) ; Configuration
+	db GDT_SIZE ; Flags
+	db 0 ; Third base
+gdt_end:
+gdt_desc:
+	dw gdt_end - gdt - 1
+	dd gdt
+
+; TSS
+tss_entry:
+	dd 0 ; Previous TSS
+	dd STACK_POINTER ; esp0
+	dd gdt_data - gdt ; ss0 (data offset)
+	dd 0 ; esp1
+	dd 0 ; ss1
+	dd 0 ; esp2
+	dd 0 ; ss2
+	dd 0 ; cr3
+	dd 0 ; eip
+	dd 0 ; eflags
+	dd 0 ; eax
+	dd 0 ; ecx
+	dd 0 ; edx
+	dd 0 ; ebx
+	dd 0 ; esp
+	dd 0 ; ebp
+	dd 0 ; esi
+	dd 0 ; edi
+	dd 0 ; es
+	dd 0 ; cs
+	dd 0 ; ss
+	dd 0 ; ds
+	dd 0 ; fs
+	dd 0 ; gs
+	dd 0 ; ldt
+	dw 0 ; trap
+	dw 0 ; iomap base
+tss_entry_end:
+
+times 1024 - ($ - $$) db 0
+
+; Start at LBA 2
+superblock:
diff --git a/boot/load.c b/boot/load.c
new file mode 100644
index 0000000..19ddce9
--- /dev/null
+++ b/boot/load.c
@@ -0,0 +1,392 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+// Independent ext2 loader
+
+typedef signed char s8;
+typedef unsigned char u8;
+
+typedef signed short s16;
+typedef unsigned short u16;
+
+typedef signed long s32;
+typedef unsigned long u32;
+
+typedef signed long long s64;
+typedef unsigned long long u64;
+
+#define BLOCK_SIZE 1024
+#define BLOCK_COUNT 256 // BLOCK_SIZE / sizeof(u32)
+#define SECTOR_SIZE 512
+#define IDE_BUSY (1 << 7)
+#define IDE_READY (1 << 6)
+#define IDE_DRIVE_FAULT (1 << 5)
+#define IDE_ERROR (1 << 0)
+#define IDE_IO 0x1F0
+#define IDE_DATA 0x0
+#define IDE_FEATURES 0x1
+#define IDE_SECTOR_COUNT 0x2
+#define IDE_LOW 0x3
+#define IDE_MID 0x4
+#define IDE_HIGH 0x5
+#define IDE_HEAD 0x6
+#define IDE_CMD 0x7
+#define IDE_ALTERNATE 0x3F6
+#define LBA_LOW(c) ((u8)(c & 0xFF))
+#define LBA_MID(c) ((u8)(c >> 8) & 0xFF)
+#define LBA_HIGH(c) ((u8)(c >> 16) & 0xFF)
+#define LBA_LAST(c) ((u8)(c >> 24) & 0xF)
+#define IDE_CMD_READ (BLOCK_SIZE / SECTOR_SIZE == 1) ? 0x20 : 0xC4
+#define IDE_CMD_WRITE (BLOCK_SIZE / SECTOR_SIZE == 1) ? 0x30 : 0xC5
+#define IDE_CMD_READ_MUL 0xC4
+#define IDE_CMD_WRITE_MUL 0xC5
+
+#define EXT2_BOOT 0
+#define EXT2_SUPER 1
+#define EXT2_ROOT 2
+#define EXT2_MAGIC 0x0000EF53
+
+struct superblock {
+	u32 total_inodes;
+	u32 total_blocks;
+	u32 su_res_blocks; // Superuser reserved
+	u32 free_blocks;
+	u32 free_inodes;
+	u32 superblock_block_num;
+	u32 log2_block_size;
+	u32 log2_frag_size;
+	u32 blocks_per_group;
+	u32 frags_per_group;
+	u32 inodes_per_group;
+	u32 last_mount_time;
+	u32 last_write_time;
+	u16 mounts_since_fsck;
+	u16 max_mounts_since_fsck;
+	u16 magic;
+	u16 state; // 1 clean; 2 errors
+	u16 error_action;
+	u16 minor_version;
+	u32 last_fsck_time;
+	u32 max_time_since_fsck;
+	u32 creator_os_id;
+	u32 major_version;
+	u16 res_block_uid;
+	u16 res_block_gid;
+};
+
+struct bgd {
+	u32 block_bitmap;
+	u32 inode_bitmap;
+	u32 inode_table;
+	u16 free_blocks;
+	u16 free_inodes;
+	u16 used_dirs;
+	u16 pad;
+	u8 bg_reserved[12];
+};
+
+struct inode {
+	u16 mode;
+	u16 uid;
+	u32 size;
+
+	u32 last_access_time;
+	u32 creation_time;
+	u32 last_modification_time;
+	u32 deletion_time;
+
+	u16 gid;
+	u16 link_count;
+	u32 blocks;
+	u32 flags;
+	u32 os_specific_val1;
+	u32 block[15];
+	u32 generation;
+
+	u32 reserved1;
+	u32 reserved2;
+
+	u32 fragment_addr;
+	u8 os_specific_val2[12];
+};
+
+#define INODE_SIZE (sizeof(struct inode))
+
+struct dirent {
+	u32 inode_num;
+	u16 total_len;
+	u8 name_len;
+	u8 type_indicator;
+	u8 name[];
+};
+
+struct file {
+	struct inode inode;
+	u32 pos;
+	u8 block_index;
+	u8 *buf;
+	u32 curr_block_pos;
+};
+
+static u32 heap;
+void *read_inode(struct inode *in);
+struct inode *get_inode(int i);
+int find_inode(const char *name, int dir_inode);
+void serial_install();
+void serial_print(const char *data);
+int main()
+{
+	serial_install();
+	heap = 0xf000;
+	void (*entry)();
+	*(void **)(&entry) = read_inode(get_inode(find_inode("kernel.bin", 2)));
+	if (entry) {
+		serial_print("Loaded kernel!\n");
+		entry();
+	}
+	return 0;
+}
+
+u8 inb(u16 port)
+{
+	u8 value;
+	__asm__ volatile("inb %1, %0" : "=a"(value) : "Nd"(port));
+	return value;
+}
+
+void insl(u16 port, void *addr, int n)
+{
+	__asm__ volatile("cld; rep insl"
+			 : "=D"(addr), "=c"(n)
+			 : "d"(port), "0"(addr), "1"(n)
+			 : "memory", "cc");
+}
+
+void outb(u16 port, u8 data)
+{
+	__asm__ volatile("outb %0, %1" ::"a"(data), "Nd"(port));
+}
+
+void *memcpy(void *dst, const void *src, u32 n)
+{
+	const char *sp = (const char *)src;
+	char *dp = (char *)dst;
+	for (; n != 0; n--)
+		*dp++ = *sp++;
+	return dst;
+}
+
+void *memset(void *dst, char val, u32 n)
+{
+	char *temp = (char *)dst;
+	for (; n != 0; n--)
+		*temp++ = val;
+	return dst;
+}
+
+int strncmp(const char *s1, const char *s2, u32 n)
+{
+	const u8 *c1 = (const u8 *)s1;
+	const u8 *c2 = (const u8 *)s2;
+	u8 ch;
+	int d = 0;
+
+	while (n--) {
+		d = (int)(ch = *c1++) - (int)*c2++;
+		if (d || !ch)
+			break;
+	}
+
+	return d;
+}
+
+u32 strlen(const char *s)
+{
+	const char *ss = s;
+	while (*ss)
+		ss++;
+	return ss - s;
+}
+
+void serial_install()
+{
+	outb(0x3f8 + 1, 0x00);
+	outb(0x3f8 + 3, 0x80);
+	outb(0x3f8 + 0, 0x03);
+	outb(0x3f8 + 1, 0x00);
+	outb(0x3f8 + 3, 0x03);
+	outb(0x3f8 + 2, 0xC7);
+	outb(0x3f8 + 4, 0x0B);
+}
+
+int is_transmit_empty()
+{
+	return inb(0x3f8 + 5) & 0x20;
+}
+
+void serial_put(char ch)
+{
+	while (is_transmit_empty() == 0)
+		;
+	outb(0x3f8, (u8)ch);
+}
+
+void serial_print(const char *data)
+{
+	for (u32 i = 0; i < strlen(data); i++)
+		serial_put(data[i]);
+}
+
+void *malloc(u32 size)
+{
+	return (u32 *)(heap += size);
+}
+
+int ide_wait(int check)
+{
+	char r;
+
+	// Wait while drive is busy. Once just ready is set, exit the loop
+	while (((r = (char)inb(IDE_IO | IDE_CMD)) & (IDE_BUSY | IDE_READY)) != IDE_READY)
+		;
+
+	// Check for errors
+	if (check && (r & (IDE_DRIVE_FAULT | IDE_ERROR)) != 0)
+		return 0xF;
+	return 0;
+}
+
+void *ide_read(void *b, u32 block)
+{
+	int sector_per_block = BLOCK_SIZE / SECTOR_SIZE; // 2
+	int sector = block * sector_per_block;
+
+	ide_wait(0);
+	outb(IDE_IO | IDE_SECTOR_COUNT, sector_per_block); // Number of sectors
+	outb(IDE_IO | IDE_LOW, LBA_LOW(sector));
+	outb(IDE_IO | IDE_MID, LBA_MID(sector));
+	outb(IDE_IO | IDE_HIGH, LBA_HIGH(sector));
+
+	// Slave/Master << 4 and last 4 bits
+	outb(IDE_IO | IDE_HEAD, 0xE0 | (1 << 4) | LBA_LAST(sector));
+	outb(IDE_IO | IDE_CMD, IDE_CMD_READ);
+	ide_wait(0);
+
+	// Read-only
+	insl(IDE_IO, b, BLOCK_SIZE / 4);
+
+	return b;
+}
+
+void *buffer_read(int block)
+{
+	return ide_read(malloc(BLOCK_SIZE), block);
+}
+
+struct superblock *get_superblock()
+{
+	struct superblock *sb = buffer_read(EXT2_SUPER);
+	if (sb->magic != EXT2_MAGIC)
+		return 0;
+	return sb;
+}
+
+struct bgd *get_bgd()
+{
+	return buffer_read(EXT2_SUPER + 1);
+}
+
+struct inode *get_inode(int i)
+{
+	struct superblock *s = get_superblock();
+	//assert(s);
+	struct bgd *b = get_bgd();
+	//assert(b);
+
+	int block_group = (i - 1) / s->inodes_per_group;
+	int index = (i - 1) % s->inodes_per_group;
+	int block = (index * INODE_SIZE) / BLOCK_SIZE;
+	b += block_group;
+
+	u32 *data = buffer_read(b->inode_table + block);
+	struct inode *in =
+		(struct inode *)((u32)data + (index % (BLOCK_SIZE / INODE_SIZE)) * INODE_SIZE);
+	return in;
+}
+
+u32 read_indirect(u32 indirect, u32 block_num)
+{
+	char *data = buffer_read(indirect);
+	return *(u32 *)((u32)data + block_num * sizeof(u32));
+}
+
+void *read_inode(struct inode *in)
+{
+	//assert(in);
+	if (!in)
+		return 0;
+
+	int num_blocks = in->blocks / (BLOCK_SIZE / SECTOR_SIZE);
+
+	//assert(num_blocks != 0);
+	if (!num_blocks)
+		return 0;
+
+	/* u32 sz = BLOCK_SIZE * num_blocks; */
+	/* void *buf = malloc(sz); */
+	void *buf = (void *)0x50000;
+	//assert(buf != 0);
+
+	int indirect;
+
+	int blocknum;
+	char *data;
+	for (int i = 0; i < num_blocks; i++) {
+		if (i < 12) {
+			blocknum = in->block[i];
+			data = buffer_read(blocknum);
+			memcpy((u32 *)((u32)buf + i * BLOCK_SIZE), data, BLOCK_SIZE);
+		} else if (i < BLOCK_COUNT + 12) {
+			indirect = in->block[12];
+			blocknum = read_indirect(indirect, i - 12);
+			data = buffer_read(blocknum);
+			memcpy((u32 *)((u32)buf + (i - 1) * BLOCK_SIZE), data, BLOCK_SIZE);
+		} else {
+			indirect = in->block[13];
+			blocknum = read_indirect(indirect, (i - (BLOCK_COUNT + 12)) / BLOCK_COUNT);
+			blocknum = read_indirect(blocknum, (i - (BLOCK_COUNT + 12)) % BLOCK_COUNT);
+			data = buffer_read(blocknum);
+			memcpy((u32 *)((u32)buf + (i - 1) * BLOCK_SIZE), data, BLOCK_SIZE);
+		}
+	}
+
+	return buf;
+}
+
+int find_inode(const char *name, int dir_inode)
+{
+	if (!dir_inode)
+		return -1;
+
+	struct inode *i = get_inode(dir_inode);
+
+	char *buf = malloc(BLOCK_SIZE * i->blocks / 2);
+	memset(buf, 0, BLOCK_SIZE * i->blocks / 2);
+
+	for (u32 q = 0; q < i->blocks / 2; q++) {
+		char *data = buffer_read(i->block[q]);
+		memcpy((u32 *)((u32)buf + q * BLOCK_SIZE), data, BLOCK_SIZE);
+	}
+
+	struct dirent *d = (struct dirent *)buf;
+
+	u32 sum = 0;
+	do {
+		// Calculate the 4byte aligned size of each entry
+		sum += d->total_len;
+		if (strncmp((void *)d->name, name, d->name_len) == 0) {
+			return d->inode_num;
+		}
+		d = (struct dirent *)((u32)d + d->total_len);
+
+	} while (sum < (1024 * i->blocks / 2));
+	return -1;
+}