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%ifndef _CONSOLE_ASM
%define _CONSOLE_ASM
%include "constants.asm"
%include "stdio.asm"
%include "string.asm"
%include "keyboard.asm"
MAX_ROWS equ 25
MAX_COLS equ 80
putc:
; Write single character at cursor position
push bp
mov bp, sp
pusha
cmp al, 20h
jl .non_graphical
mov ah, 0ah ; BIOS - write character
mov bx, 00h ; video page zero
mov cx, 01h ; repeat character N times
int 10h ; BIOS video service
.non_graphical:
push ax
call console_driver
add sp, 2
popa
mov sp, bp
pop bp
ret
console_scroll_up:
cmp dh, MAX_ROWS - 1
jne .no_action
mov dh, MAX_ROWS - 2
push dx
call setcursor
add sp, 2
; scroll window up:
mov ah, 06h ; scroll up function id.
mov al, 1 ; lines to scroll.
mov bx, 0700h ; attribute for new lines.
mov cl, 0 ; upper col.
mov ch, 0 ; upper row.
mov dl, MAX_COLS ; lower col.
mov dh, MAX_ROWS ; lower row.
int 10h
.no_action:
ret
console_driver:
push bp
mov bp, sp
call console_cursor_getpos
mov dh, [cursor_row]
mov dl, [cursor_col]
mov ax, [bp + 4]
.do_fn:
.do_scancode:
cmp al, 00h ; when AL is 00h, check scan-code
jne .do_ascii
cmp ah, SC_ARROW_LEFT
je .handle_sc_arrow_left
cmp ah, SC_ARROW_RIGHT
je .handle_sc_arrow_right
.handle_sc_arrow_left:
dec dl
jmp .return
.handle_sc_arrow_right:
inc dl
jmp .return
.do_ascii:
; ASCII control block
cmp al, SPC
jae .handle_SPC
cmp al, TAB
je .handle_TAB
cmp al, BS
je .handle_BS
cmp al, CR
je .handle_CR
cmp al, LF
je .handle_LF
; etc...
jmp .return
.handle_SPC:
inc dl
cmp dl, MAX_COLS
jge .handle_CR
jmp .return
.handle_TAB:
add dl, 4
jmp .return
.handle_BS:
dec dl
cmp dl, 0
jl .skip_bs
push dx
call setcursor
add sp, 2
.skip_bs:
mov ah, 0ah
mov al, 20h
mov bx, 00h
mov cx, 1
int 10h
jmp .return_noupdate
.handle_CR:
mov dl, 0 ; set column zero
; fall through
.handle_LF:
inc dh ; increment row
jmp .return
.return:
push dx
call setcursor
add sp, 2
.return_noupdate:
call console_scroll_up
mov sp, bp
pop bp
ret
cls:
push bp
mov bp, sp
pusha
mov ah, 07h ; BIOS - scroll down
mov al, 00h ; lines to scroll (0 == entire screen)
mov bx, 0700h ; color white/black
; & video page zero
mov cx, 0
mov dh, 24 ; rows
mov dl, 79 ; cols
int 10h ; BIOS video service
popa
mov sp, bp
pop bp
ret
console_cursor_getpos:
push bp
mov bp, sp
pusha
mov ah, 03h ; BIOS - query cursor position and size
mov bh, 00h ; video page zero
int 10h
mov [cursor_sl_start], byte ch ; record data
mov [cursor_sl_end], byte cl
mov [cursor_row], byte dh
mov [cursor_col], byte dl
popa
mov sp, bp
pop bp
ret
console_cursor_read:
push bp
mov bp, sp
push ax
push bx
mov ah, 08h ; BIOS - read character/attr at cursor
mov bh, 00h ; video page zero
int 10h
mov [cursor_attr], byte ah
mov [cursor_char], byte al
pop bx
pop ax
mov sp, bp
pop bp
ret
console_cursor_read_last:
push bp
mov bp, sp
push dx
call console_cursor_getpos
mov dh, [cursor_row]
mov dl, [cursor_col]
cmp dh, 0 ; is this column zero?
je .finalize
sub dl, 1 ; previous column
js .prev_row ; column went negative
jmp .finalize
.prev_row:
cmp dh, 0 ; is this row zero?
je .return
sub dh, 1 ; go up one row
add dl, 80 ; return to last column of row (-1 + 80 = 79)
.finalize:
push dx
call setcursor
call console_cursor_getpos
call console_cursor_read
; restore original cursor position
mov dh, [cursor_row]
mov dl, [cursor_col]
push dx
call setcursor
.return:
add sp, 4
pop dx
mov sp, bp
pop bp
ret
setcursor:
push bp
mov bp, sp
pusha
mov ah, 02h ; BIOS - set cursor position
mov bh, 0 ; video page zero
mov dx, [bp + 4] ; address of new cursor value
int 10h ; BIOS video service
popa
mov sp, bp
pop bp
ret
; data
cursor_sl_start: db 0
cursor_sl_end: db 0
cursor_row: db 0
cursor_col: db 0
cursor_row_vram: dw 0
cursor_col_vram: dw 0
cursor_vram: dw 0
cursor_attr: db 0
cursor_char: db 0
%endif
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