diff options
Diffstat (limited to 'src/entry.asm')
| -rw-r--r-- | src/entry.asm | 29 |
1 files changed, 8 insertions, 21 deletions
diff --git a/src/entry.asm b/src/entry.asm index 67b5ffd..ac70091 100644 --- a/src/entry.asm +++ b/src/entry.asm @@ -4,14 +4,17 @@ ; Definitions -%define LOCATION 0x7c00 ; Bootloader location - ; 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 @@ -158,8 +161,6 @@ lba_error: ; Video map routine video_map: - xor eax, eax - mov es, ax mov bx, VESA_START ; Set load address mov di, bx mov ax, VESA_GET_MODES ; Get video modes @@ -187,7 +188,6 @@ video_map: cmp ax, VESA_SUCCESS_SIG ; Check if call succeeded jne .error ; Nope, jump to error! - xor ax, ax mov ax, [es:di + VESA_FRAMEBUFFER_OFFSET] ; Save framebuffer mov [.framebuffer], ax ; Move fb address to struct @@ -209,7 +209,6 @@ video_map: lea ax, [es:di - 0x100] mov [vid_info.array], ax .set_mode: - xor ax, ax mov ax, VESA_SET_MODE ; Set VBE mode mov bx, [.mode] ; Set mode address mov [vid_info], bx ; Move mode information to array @@ -257,8 +256,8 @@ lba: dd 0 ; More storage bytes ; End of boot sector -times 510 - ($ - $$) db 0 -dw 0xAA55 +times SECTOR_SIZE - ($ - $$) 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 @@ -297,9 +296,6 @@ stage_two: jmp protected_mode_enter kernel_load: - xor ax, ax ; Clear ax - mov dx, ax ; Clear dx - ; TODO: Add singly pointer support (until ~12KiB) ;cmp cx, EXT2_DIRECT_POINTER_COUNT ; Indirect pointer needed? ;jge .indirect ; Singly indirect pointer @@ -316,8 +312,6 @@ kernel_load: ; push bx ; push cx ; -; xor ebx, ebx -; ; ; Read singly indirect pointer ; mov bx, EXT2_GET_ADDRESS(EXT2_KERNEL_INODE) ; First block ; lea di, [bx + EXT2_IND_POINTER_OFFSET] ; Address of singly indirect pointer @@ -363,13 +357,6 @@ protected_mode_enter: out A20_GATE, al .a20_enabled: - ; Clear registers - xor ax, ax - mov ds, ax - mov es, ax - mov fs, ax - mov gs, ax - lgdt [gdt_desc] ; Load GDT ; Set protected mode via cr0 @@ -390,7 +377,7 @@ protected_mode: mov esp, STACK_POINTER ; Move stack pointer - mov ax, gdt_tss - gdt ; Load TSS + mov ax, (gdt_tss - gdt) | 0b11 ; Load TSS in ring 3 ltr ax mov eax, vid_info ; Pass VBE struct to kernel |