A Questions about keys

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adroit

Joined: 21 Feb 2010
Posts: 252

adroit 04 Mar 2010, 21:45

Hey, all. What are the hexadecimal for the direction keys, example:
Left, Up, Right, Down

And how do I implement them in the following code:

Code:

...
xor ax,ax
int 16h

;check for keys
 cmp ('direction key up here'),al
 je MOVE_UP
 cmp ('direction key down here'),al
 je MOVE_DOWN
...

Im planning to use them in my CLI(Shell). And also, is there a possible way (in DOS) to determine where the mouse is on the screen and if so, when the user right clicks, a command is executed on that pre-determined area.
Can someone help me in both questions
?? Sad

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meshnix

04 Mar 2010, 21:45

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 04 Mar 2010, 22:22

See SCAN CODES here: http://stanislavs.org/helppc/int_16.html

04 Mar 2010, 22:22

zhak

Joined: 12 Apr 2005
Posts: 501
Location: Belarus

zhak 04 Mar 2010, 22:22

Fn 0 Int 0x16 returns the following values on Arrow key press:
UP: AX = 0x4800
DOWN: AX = 0x5000
RIGHT: AX = 0x4B00
LEFT: AX = 0x4D00

you can use smth like

Code:

.wait_key:
    xor ax, ax
    int 0x16
    cmp ax, 0x5000  ;down arrow key?
    jz short .down
    cmp ax, 0x4800  ;up arrow key?
    jz short .up
    . . .
    cmp al, 13  ;enter key pressed?
    jnz short .wait_key
.process:
 . . . enter key pressed
    jmp

04 Mar 2010, 22:22

edfed

Joined: 20 Feb 2006
Posts: 4354
Location: Now

edfed 04 Mar 2010, 22:31

mov ax,3
int 33h
mov [mouse.x],ecx
mov [mouse.y],edx
mov [status],bl ;bit 0=left bit 1=right

04 Mar 2010, 22:31

adroit

Joined: 21 Feb 2010
Posts: 252

adroit 04 Mar 2010, 22:41

Thanks guys!!
I have 2 questions (again)
Zhak, why did u use a short jump? (i never understood the short jump)
Edfed, why did you use 32-bit registers, instead of 16-bit?

04 Mar 2010, 22:41

zhak

Joined: 12 Apr 2005
Posts: 501
Location: Belarus

zhak 04 Mar 2010, 23:07

i use short prefix to control code size. i want my Jcc instructions to be 2-bytes long. also, sometimes i need my code to be compatible with 8086 until i perform cpu check, and that cpus don't support near jumps (4-byte opcodes)

04 Mar 2010, 23:07

adroit

Joined: 21 Feb 2010
Posts: 252

adroit 04 Mar 2010, 23:13

Ahhh, i see. thanks.

04 Mar 2010, 23:13

edfed

Joined: 20 Feb 2006
Posts: 4354
Location: Now

edfed 05 Mar 2010, 06:16

because it is my personnal way to code. 16 bits is dead.

of course,x & y are not 32bits but 16bits in cx and dx

05 Mar 2010, 06:16

adroit

Joined: 21 Feb 2010
Posts: 252

adroit 05 Mar 2010, 14:01

That is sort of true, but I still prefer 16-bit coding, as I am just a beginner of assembly programming

05 Mar 2010, 14:01

edfed

Joined: 20 Feb 2006
Posts: 4354
Location: Now

edfed 05 Mar 2010, 14:29

32 bit is easier than 16 bit. Smile

05 Mar 2010, 14:29

adroit

Joined: 21 Feb 2010
Posts: 252

adroit 05 Mar 2010, 22:25

ohhh...

05 Mar 2010, 22:25

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