diff options
Diffstat (limited to 'src/stage2_functions.asm')
| -rw-r--r-- | src/stage2_functions.asm | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/src/stage2_functions.asm b/src/stage2_functions.asm new file mode 100644 index 0000000..018cf6a --- /dev/null +++ b/src/stage2_functions.asm @@ -0,0 +1,108 @@ +VIDEO_MEMORY equ 0xb8000 + +VIDEO_COLS equ 80 +VIDEO_ROWS equ 25 + +CURSOR_X: + dw 0 + +CURSOR_Y: + dw 0 + +pm_print_newline: + push eax + mov [CURSOR_X], word 0 + mov ax, [CURSOR_Y] + inc ax + mov [CURSOR_Y], ax + pop eax + call update_vga_cursor + ret + +; IN si +pm_print_string: + push eax +_loop_pm_print_string: + lodsb + cmp al, 0 + je pm_print_string_fini + call pm_print_char + jmp _loop_pm_print_string +pm_print_string_fini: + pop eax + ret + +; IN al: character to print +pm_print_char: + push edx + push ecx + push ebx + push eax + mov ax, [CURSOR_Y] + mov cl, VIDEO_COLS + mul cl + mov bx, [CURSOR_X] + add ax, bx + shl ax, 1 + mov edx, VIDEO_MEMORY + add dx, ax + pop eax + mov ah, 0x07 + mov [edx], ax + pop ebx + pop ecx + pop edx + call inc_cursor + ret + +inc_cursor: + push eax + mov ax, [CURSOR_X] + inc ax + mov [CURSOR_X], ax + cmp ax, VIDEO_COLS + jl inc_cursor_fini + mov [CURSOR_X], word 1 + mov ax, [CURSOR_Y] + inc ax + mov [CURSOR_Y], ax + cmp ax, VIDEO_ROWS + jl inc_cursor_fini + ; TODO: scoll one line, for now restart on top + mov [CURSOR_Y], word 0 +inc_cursor_fini: + call update_vga_cursor + pop eax + ret + +; update the VGA cursor on screen +update_vga_cursor: + push ebx + push ecx + push edx + mov al, [CURSOR_Y] + mov cl, VIDEO_COLS + mul cl + mov bx, ax + movzx ax, [CURSOR_X] + add bx, ax + mov cx, bx + ;cursor LOW port to vga INDEX register + mov al, 0fh ;Cursor Location Low Register -- + mov dx, 3d4h ;VGA port 3D4h + out dx, al + mov ax, cx ;restore 'postion' back to AX + mov dx, 3d5h ;VGA port 3D5h + out dx, al ;send to VGA hardware + ;cursor HIGH port to vga INDEX register + mov al, 0eh + mov dx, 3d4h ;VGA port 3D4h + out dx, al + mov ax, cx ;restore 'position' back to AX + shr ax, 8 ;get high byte in 'position' + mov dx, 3d5h ;VGA port 3D5h + out dx, al ;send to VGA hardware + pop edx + pop ecx + pop ebx + ret |