nightloader/code/legacy-bios/bootsector/utility.asm

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2023-04-24 20:00:51 +00:00
2023-04-25 19:12:35 +00:00
; cx: len_buffer
; si: buffer
; dl: start_x NOTE: Will contain the end of the text on-screen
; dh: start_y NOTE: Will contain the end of the text on-screen
print_string:
.prolog:
push di
push cx
push bx
push ax
xor di, di ; character index
.printing_loop:
.set_cursor_position:
mov ah, 0x02
mov bh, 0
int 0x10
.write_character:
push cx ; save len_buffer
; get the current character
mov bx, si
add bx, di
mov al, [bx]
; al now contains the current character
; set the other needed interrupt values
mov ah, 0x0a ; wanted function (write character at cursor position)
mov bh, 0 ; page number
mov cx, 1 ; repetitions of character
int 0x10 ; call bios basic draw functions
pop cx ; restore len_buffer
inc dl ; go to next column
; go to a new line if needed
cmp dl, 80
jb .no_new_line_needed
xor dl, dl
inc dh ; increase column
.no_new_line_needed:
inc di ; go to next character
; go further if the string-printing hasn't been finished
cmp di, cx
jb .printing_loop
.epilog:
pop ax
pop bx
pop cx
pop di
ret