diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/boot/boot.stage1.asm | 1 | ||||
| -rw-r--r-- | src/boot/boot.stage2.a20.asm | 135 | ||||
| -rw-r--r-- | src/boot/boot.stage2.asm | 40 | ||||
| -rw-r--r-- | src/boot/boot.stage2.print.asm | 54 |
4 files changed, 78 insertions, 152 deletions
diff --git a/src/boot/boot.stage1.asm b/src/boot/boot.stage1.asm index a67e7fa..6bed463 100644 --- a/src/boot/boot.stage1.asm +++ b/src/boot/boot.stage1.asm @@ -30,6 +30,7 @@ _start: int 0x13 ; Read disk jc _disk_read_err + mov dl, [drive] jmp 0x0000:STAGE2_ADDR diff --git a/src/boot/boot.stage2.a20.asm b/src/boot/boot.stage2.a20.asm index 3c69d79..d0b52c4 100644 --- a/src/boot/boot.stage2.a20.asm +++ b/src/boot/boot.stage2.a20.asm @@ -1,147 +1,46 @@ - ;; boot.stage2.a20.asm - section .stage2 + ;; boot.stage2.a20.asm _enable_a20: - call _check_a20 - test ax, ax - jnz .end + cli - call _enable_a20_bios - call _check_a20 - test ax, ax - jnz .end - - call _enable_a20_keyb - call _check_a20 - test ax, ax - jnz .end - - call _enable_a20_io92 - call _check_a20 - test ax, ax - jnz .end - - .halt: hlt - jmp .halt - .end: - ret - -_check_a20: - pushf - push ds - push es - push di - push si - cli ; Clear Interrupts - - xor ax, ax - mov es, ax - not ax - mov ds, ax - ;; 0500 and 0510 are guaranteed to be free - mov di, 0x0500 - mov si, 0x0510 - - ;; Save the original values - mov dl, byte [es:di] - push dx - mov dl, byte [ds:si] - push dx - - mov byte [es:di], 0x00 - mov byte [ds:si], 0xFF - cmp byte [es:di], 0xFF - - mov ax, 0 ; The A20 is disabled - je .a20_disabled - mov ax, 1 ; The A20 is enabled - .a20_disabled: - pop dx - mov byte [ds:si], dl - pop dx - mov byte [es:di], dl - - pop si - pop di - pop es - pop ds - popf - sti ; Enable interrupts again - ret - -_enable_a20_bios: - mov ax, 0x2401 - int 0x15 - jc .fast_gate - test ah, ah - jnz .failed - call _check_a20 - test ax, ax - jnz .done - - .fast_gate: - in al, 0x92 - test al, 2 - jnz .done - - or al, 2 - and al, 0xfe - out 0x92, al - - call _check_a20 - test ax, ax - jnz .done - - .done: - mov ax, 1 - ret - - .failed: - mov ax, 0 - ret - -_enable_a20_keyb: - cli + ;; Disable keyboard call .wait_io1 mov al, 0xad out 0x64, al + ;; Read from keyboard controller call .wait_io1 - mov al, 0x0d0 + mov al, 0xd0 out 0x64, al call .wait_io2 in al, 0x60 - push eax + push eax ; Save current value + + ;; Write back with the A20 bit set call .wait_io1 mov al, 0xd1 out 0x64, al call .wait_io1 + pop eax + or al, 2 ; Set A20 bit + + ;; Enable keyboard + call .wait_io1 mov al, 0xae out 0x64, al - - sti - ret + call .wait_io1 + .wait_io1: in al, 0x64 test al, 2 jnz .wait_io1 ret - - .wait_io2: + + .wait_io2: in al, 0x64 test al, 1 jz .wait_io2 ret - -_enable_a20_io92: - in al, 0x92 ; Read from port 0x92 - test al, 2 ; Check if bit 1 - jnz .end - or al, 2 - and al, 0xfe - out 0x92, al - .end: - ret diff --git a/src/boot/boot.stage2.asm b/src/boot/boot.stage2.asm index 52c73e5..968bedc 100644 --- a/src/boot/boot.stage2.asm +++ b/src/boot/boot.stage2.asm @@ -3,6 +3,8 @@ [bits 16] [org 0x7e00] + %include "common.asm" + jmp 0x0000:_s2_entry _s2_entry: @@ -10,6 +12,19 @@ _s2_entry: xor ax, ax mov ds, ax + mov si, DAP_kernel + mov ah, 0x42 + int 0x13 + jc _kernel_load_err + jmp _kernel_loaded + +_kernel_load_err: + mov si, boot_kernel_err + call _print_string + + jmp $ + +_kernel_loaded: mov si, boot_s2_msg call _print_string @@ -27,21 +42,34 @@ _s2_entry: _protected_mode: mov ax, DATA_SEG32 mov ds, ax + mov ss, ax mov esp, 0x90000 + and esp, 0xFFFFFFF0 ; Align to 16-byte boundary mov esi, boot_protmode_msg call _print_string_pm_vga call 0x10000 - - jmp $ +boot_s2_msg: + db "Entering Stage 2", 13, 10, 0 +boot_protmode_msg: + db "Enabling Protected Mode", 13, 10, 0 +boot_kernel_err: + db "Error loading kernel from disk", 13, 10, 0 + + + align 16 +DAP_kernel: + db 0x10 + db 0 + dw 1 ; Number of sectors + dw 0x0000 + dw 0x1000 ; Offset + dq 66 ; Starting sector + %include "boot.stage1.print.asm" %include "boot.stage2.a20.asm" %include "boot.stage2.gdt32.asm" %include "boot.stage2.print.asm" -boot_s2_msg: - db "Entering Stage 2", 13, 10, 0 -boot_protmode_msg: - db "Enabling Protected Mode", 13, 10, 0 diff --git a/src/boot/boot.stage2.print.asm b/src/boot/boot.stage2.print.asm index d567d6d..4527b87 100644 --- a/src/boot/boot.stage2.print.asm +++ b/src/boot/boot.stage2.print.asm @@ -1,39 +1,37 @@ ;; boot.stage2.print.asm - - section .stage2 %define VGA_BUFFER 0xb8000 %define WB_COLOR 0xf _print_string_pm_vga: - mov eax, [esi] - lea esi, [esi+1] - cmp al, 0 - jne .print_char_pm_vga - add byte [pos_x], 0 - add byte [pos_y], 1 - ret + pusha + mov edi, VGA_BUFFER + mov ah, WB_COLOR + xor ecx, ecx + xor edx, edx - .print_char_pm_vga: - mov ah, WB_COLOR ; White on black - mov ecx, eax - movzx eax, byte [pos_y] - mov edx, 160 - mul edx - movzx ebx, byte [pos_x] - shl ebx, 1 - - mov edi, VGA_BUFFER ; Video memory start - add edi, ebx ; Add X offset - add edi, eax ; Add Y offset - - mov eax, ecx ; Restore char - mov word [ds:edi], ax - add byte [pos_x], 1 ; Advance to right - ret + .print_loop: + lodsb + test al, al + jz .done -pos_x: db 0 -pos_y: db 0 + push eax + mov eax, edx + imul eax, eax, 160 + lea edi, [VGA_BUFFER + eax] + lea edi, [edi + ecx * 2] + pop eax + ;; Advance cursor + inc cl + cmp cl, 80 + jb .print_loop + xor cl, cl + inc dl + + jmp .print_loop + .done: + popa + ret |