diff options
Diffstat (limited to 'boot')
| -rw-r--r-- | boot/entry.asm | 48 |
1 files changed, 42 insertions, 6 deletions
diff --git a/boot/entry.asm b/boot/entry.asm index c6b36f0..0379133 100644 --- a/boot/entry.asm +++ b/boot/entry.asm @@ -41,13 +41,16 @@ %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_ROOT_INODE 0x02 ; Root 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_ENTRY_LENGTH_OFFSET 0x04 ; Dirent offset of entry length +%define EXT2_FILENAME_OFFSET 0x08 ; Dirent offset of filename +%define EXT2_INODE_OFFSET 0x00 ; Dirent offset of inode number %define EXT2_SIG 0xef53 ; Signature ; Video constants (VESA) @@ -235,6 +238,12 @@ video_map: 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 +found_msg db "FOUND!", NEWLINE, RETURN, NULL + +; Filenames +loader_name db "load.bin" +loader_name_len equ $ - loader_name + drive db 0 ; Video info struct @@ -280,22 +289,49 @@ stage_two: mov [dest], bx call disk_read - ; Load kernel - mov bx, EXT2_GET_ADDRESS(EXT2_KERNEL_INODE) ; First block + ; Load root directory + mov bx, EXT2_GET_ADDRESS(EXT2_ROOT_INODE) ; First block + mov ax, [bx + EXT2_POINTER_OFFSET] ; Address of first block pointer + shl ax, 1 ; Multiply ax by 2 + mov [lba], ax + mov bx, 0x3500 ; Load to this address + mov [dest], bx + call disk_read + +.search_loop: + lea si, [bx + EXT2_FILENAME_OFFSET] ; First comparison string + mov di, loader_name ; Second comparison string + mov cx, loader_name_len ; String length + rep cmpsb ; Compare strings + je .found ; Found loader! + add bx, EXT2_ENTRY_LENGTH_OFFSET ; Add dirent struct size + jmp .search_loop ; Next dirent! +.found: + mov si, found_msg + call print ; Print success message + mov ax, word [bx + EXT2_INODE_OFFSET] ; Get inode number from dirent + ; Calculate address: (EXT2_INODE_TABLE_LOC + (inode - 1) * EXT2_INODE_SIZE) + dec ax ; (inode - 1) + mov cx, EXT2_INODE_SIZE ; Prepare for multiplication + mul cx ; Multiply inode number + mov bx, ax ; Transfer calculation + add bx, EXT2_INODE_TABLE_LOC ; bx is at the start of the inode now! mov cx, [bx + EXT2_COUNT_OFFSET] ; Number of blocks for inode + cmp cx, 0 + je disk_error 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 + call inode_load ; Set video mode call video_map jmp protected_mode_enter -kernel_load: +inode_load: mov ax, [di] ; Set ax = block pointer shl ax, 1 ; Multiply ax by 2 mov [lba], ax @@ -307,7 +343,7 @@ kernel_load: add bx, 0x400 ; 1kb increase add di, 0x4 ; Move to next block pointer sub cx, 0x2 ; Read 2 blocks - jnz kernel_load + jnz inode_load ret protected_mode_enter: |