.load 0x2C00
.fixed 1024, 0xFF
.entry _kernel0_main
.header KERNEL0_BOOT

@include <sdk/bios_api.dss>
@include <../drivers/display_driver.dss>
@include <../drivers/keyboard_driver.dss>
@include <memory.dss>


## =========================================================================================================================
.data
	$test_str "Hello DragonOS! :)"
	$cursor_x:1

## =========================================================================================================================




## =========================================================================================================================
.code
_kernel0_main:
	push DefaultPalette.Black
	push 1
	call $_clear_screen
	push $test_str
	push 1
	call $_print_string
	## debug_break
_infinite_loop_0:
	## jmp $_infinite_loop_0

	mov [$cursor_x], 0

	## Init Memory Handler
	push 0
	call $_init_memory_handler

	## Init Display driver
	push 0
	call $_init_display_driver

	## Init Keyboard driver
	push $_key_pressed		## KeyPressed handler address passed to the _init_keyboard subroutine
	push 1
	call $_init_keyboard_driver

_infinite_loop:
	jmp $_infinite_loop

	hlt
## =========================================================================================================================




## =========================================================================================================================
_key_pressed:
	debug_break
	mov R1, [Keyboard_Registers.KEYCODE]

	mov ACC, KeyCodes.Return
	jeq $_key_pressed_enter, R1

	push R1
	push 1
	call $_is_char_printable

	mov ACC, RV
	jne $_key_pressed_end, 1
	push R1
	mov R2, [$cursor_x]
	push R2
	push 1
	push DefaultPalette.Red
	push 4
	call $_print_char
	inc R2
	mov [$cursor_x], R2
	jmp $_key_pressed_end

_key_pressed_enter:
	mov [$cursor_x], 0
	mov R10, 0x25
	int 0x30
	jmp $_key_pressed_end

_key_pressed_end:
	ret


_is_char_printable:
	arg R9
	mov ACC, KeyCodes.Spacebar
	jls $_is_char_printable_false, R9
	mov ACC, KeyCodes.LowerCase_z
	jgr $_is_char_printable_false, R9
	mov RV, 1
	ret
_is_char_printable_false:
	mov RV, 0
	ret
## =========================================================================================================================