screen.asm

; Output line feed 
_new_line:
	pusha
	mov	eax, 4
	mov	ebx, 1
	mov	ecx, new_line
	mov	edx, 1
	int	0x80
	popa
	ret

; Clear screen
_clear_screen:
	pusha
	mov	ecx, 256
.loop:
	call	_new_line	
	loop	.loop
	
	popa
	ret

; Output String of n length
; n -> edx, addr of first char in ecx
_print_line:
	pusha
	mov	eax, 4
	mov	ebx, 1
	int	0x80
	popa
	ret

; copy n bytes n -> ecx | dest -> edi | src -> esi
_n_cpy:
	pusha	
.loop:
	movsb
	loop .loop

	popa
	ret

; n cmp -> compare strings | n-> ecx | str1 -> edi | str2 -> esi | returns 0 in eax if match
_n_cmp:
	pusha

.loop:
	mov	al, [esi]
	mov	bl, [edi]

	cmp	al, bl
	jne	.end

	inc	edi
	inc	esi

	loop	.loop

	popa
	mov	eax, 0
	ret

.end:
	popa
	mov	eax, 1
	ret

_update_targets:
	pusha
	mov	ecx, 5630
	mov	esi, world + 5630

.loop:
	cmp	[esi], byte '*'
	jne	.next
	
	mov	[esi], byte ' '
	add	esi, 120
	mov	[esi], byte '*'
	sub	esi, 120
.next:
	dec	esi
	loop	.loop

	; clear * at bottom
	mov	ecx, 200
	mov	esi, world + 5640
.loop2:
	cmp	[esi], byte '*'
	jne	.next2
	mov	[esi], byte ' '

.next2:
	inc	esi
	loop	.loop2
	
	popa
	ret

; render screen
_render:
	pusha

	mov	eax, [playerX]
	mov	eax, [playerY]

	; copy world into screen buffer 
	mov	edi, screen
	mov	esi, world
	mov	ecx, world_len
	call	_n_cpy

	; copy player into world 
	mov	edi, screen

	mov	eax, 0
	mov	edx, 0
	mov	al, [playerY]
	mov	dl, 120
	mul	dl

	add	edi, eax

	add	edi, [playerX]

	; see if player is hitting a target if so add to score
	pusha
	add	edi, 1

	cmp	[edi - 120], byte '*'
	je	.s_add

	cmp	[edi], byte '*'
	je	.s_add

	jmp	.s_end

.s_add:
	add	[score], dword 50
.s_end:
	sub	edi, 1
	popa
	; end score calc

	mov	esi, player
	mov	ecx, 3
	pusha
.loop:
	movsb
	loop	.loop
	popa

	; Print screen
	mov	ecx, screen
	mov	edx, world_len
	call	_print_line

	popa
	ret