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%include "stage3/colors.asm"
global print_chr, print_str, print_dec, print_hex, clear_screen, newline
extern memcpy
section .data
pos:
.row: db 0
.col: db 0
cursor: dq 0xB8000
color: db COLOR_WHITE | (COLOR_BLACK << 4)
section .text
set_color:
shl sil, 4
add dil, sil
mov [color], dil
update_cursor:
mov rbx, [cursor]
sub rbx, 0xB8000
shr rbx, 1
mov dx, 0x3D4
mov al, 14
out dx, al
mov dx, 0x3D5
mov al, bh
out dx, al
mov dx, 0x3D4
mov al, 15
out dx, al
mov dx, 0x3D5
mov al, bl
out dx, al
ret
set_chr:
mov rax, [cursor]
mov byte[rax], dil
inc rax
mov dil, [color]
mov [rax], dil
inc rax
mov [cursor], rax
jmp update_cursor
vertical_tab:
mov al, [pos.row]
inc al
cmp al, 25
je .scroll
mov [pos.row], al
mov rax, [cursor]
add rax, 160
mov [cursor], rax
jmp update_cursor
.scroll:
mov rdi, 0xB8000
mov rsi, 0xB80A0
mov rdx, 0xF00
jmp memcpy
carriage_return:
mov rax, [cursor]
xor rbx, rbx
mov bl, [pos.col]
shl bl, 1
sub rax, rbx
mov [cursor], rax
mov byte[pos.col], 0
jmp update_cursor
newline:
call vertical_tab
jmp carriage_return
print_chr:
cmp dil, 10
je newline
cmp dil, 11
je vertical_tab
cmp dil, 13
je carriage_return
mov al, [pos.col]
inc al
cmp al, 80
je .newline
mov [pos.col], al
jmp set_chr
.newline:
push rdi
call newline
pop rdi
jmp set_chr
print_str:
mov rax, rdi
.print:
mov dil, [rax]
cmp dil, 0
je .return
push rax
call print_chr
pop rax
inc rax
jmp .print
.return:
ret
print_hex:
mov rsi, 0x10
jmp print_num
print_dec:
mov rsi, 10
print_num:
mov rax, rdi
xor rcx, rcx
.convert:
inc rcx
xor rdx, rdx
div rsi
cmp dl, 10
jb .digit
add dl, 'A'-10
jmp .next
.digit:
add dl, '0'
.next:
push rdx
cmp rax, 0
jne .convert
.print:
cmp rcx, 0
je .return
dec rcx
pop rdi
push rcx
call print_chr
pop rcx
jmp .print
.return:
ret
clear_screen:
push rbx
push r12
push r13
push r14
push r15
mov qword[cursor], 0xB8000
.clr:
cmp qword[cursor], 0xB8FA0
je .return
mov dil, ' '
call set_chr
jmp .clr
.return:
mov qword[cursor], 0xB8000
mov byte[pos.row], 0
mov byte[pos.col], 0
call update_cursor
pop r15
pop r14
pop r13
pop r12
pop rbx
ret
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