I have a "Draw!!" message which gets printed with black color and yellow background. While on QEMU, this text gets printed without the text itself blinking (intended), but on running it on real hardware after `dd` 'ing the flat binary to a USB drive, the text itself is printed and in correct colors, but is also blinking (not-intended).
Please help me find out why is this so. Here are the relevant parts of the code:
Code: Select all
;* COLORS:
%define black 00h
%define blue 01h
%define green 02h
%define cyan 03h
%define red 04h
%define magenta 05h
%define brown 06h
%define light_gray 07h
%define dark_gray 08h
%define light_blue 09h
%define light_green 0Ah
%define light_cyan 0Bh
%define light_red 0Ch
%define light_magenta 0Dh
%define yellow 0Eh
%define white 0Fh
%define color(fore, back) (((back)<<4) | (fore))
;* gotoxy ----------------------------------------------------------------------------------
;? parameters: dh - row; dl - column
gotoxy:
mov bh, 0 ; page number (we are using 1 page only currently)
mov ah, 2 ; set cursor position
int 10h ; video interrupt
ret
;* printc ----------------------------------------------------------------------------------
;? Parameters: al - input char, bl - color
printc: ; prints char at crr cursor position
mov bh, 0 ; page number
mov cx, 1 ; number of times to write char
mov ah, 09h ; tells the interrupt call to print character stored in al to screen
int 10h ; interrupt for video functions - currently printing char
ret
;* get_cursor_pos --------------------------------------------------------------------------
;? Returns: dh - row, dl = column
get_cursor_pos:
xor bh, bh ; page number
mov ah, 03h ; get current cursor pos and size
int 10h
ret
;* increment_cursor_pos --------------------------------------------------------------------
; moves cursor to next char, going to next line if required (but never scrolls)
increment_cursor_pos:
call get_cursor_pos ; dh=row, dl=column
inc dl
cmp dl, scr_horiz_char_count ; the cursor should go to next line if equal
je _increment_cursor_pos_next_line
jmp _increment_cursor_pos_next_end
_increment_cursor_pos_next_line:
cmp dh, scr_vert_char_count-1 ; if equal, then can't go next line
je _increment_cursor_pos_next_end
inc dh ; otherwise go to next line
xor dl, dl
_increment_cursor_pos_next_end:
call gotoxy
ret
;* prints ----------------------------------------------------------------------------------
;? Parameters: si - input string, bl - color
prints: ; prints string
_prints_loop:
lodsb ; loads byte at ds:si to al and increments si
cmp al, 0 ; true if the string in si has ended
je _prints_end
call printc
call increment_cursor_pos
jmp _prints_loop
_prints_end:
ret ; return the control flow
%define draw_msg_color color(black, yellow)
%define end_msg_row crr_turn_msg_pos_y
%define end_msg_col crr_turn_msg_pos_x
%define invert_color(color) (((color & 0xF0)>>4) | ((color & 0x0F)<<4))
draw_msg: db " Draw!! ", 0 ; space padded to overwrite the crr turn msg on screen
o_won_msg: db " O won!! ", 0
x_won_msg: db " X won!! ", 0
;? Parameters: al - one of the 3 game_state_draw, game_state_*_running
print_end_msg:
mov dh, end_msg_row ; the position remains same for every case
mov dl, end_msg_col
call gotoxy
cmp al, game_state_draw
je _print_end_msg_draw
cmp al, game_state_x_won
je _print_end_msg_x_won
cmp al, game_state_o_won
je _print_end_msg_o_won
_print_end_msg_draw:
mov si, draw_msg
mov bl, draw_msg_color
call prints
ret
_print_end_msg_x_won:
mov si, x_won_msg
mov bl, invert_color(x_player_color)
call prints
ret
_print_end_msg_o_won:
mov si, o_won_msg
mov bl, invert_color(o_player_color)
call prints
ret
What causes this? How can I resolve it?
---
Thank you for your time reading through this! Your help is appreciated
Regards
@lakroh
(a beginner)
