Done correctly?

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Steve

Joined: 10 Sep 2005
Posts: 10

Steve 01 Apr 2006, 22:55

Hi, I decided to take a stab at a 'Get Keystroke' type program. Right now, it seems like it is completed.

Here is the code:

Code:

org 100h
use16

Main:

mov ah, 9h ; AH = 9h / INT = 21h : Print Text
mov dx, mText ; Move mText into the data register.

int 21h ; Execute 'Print Text' interrupt.

InputCheck:

mov ah, 00h  ; AH = 00h / INT = 16h : Get Keystroke

int 16h ; Get keystroke.

cli ; Disable interrupts.

cmp al, 'y' ; Check if AL holds 'y'.

je Main ; AL holds 'y', time to loop.

cmp al, 'n' ; Check if AL holds 'n'.

jne InputCheck ; AL doesn't hold 'n' so we check again.

jmp Exit ; AL holds 'n' so we jump to Exit.

Exit:

sti ; Enable intterupts again.

int 20h ; Exit interrupt.

mText db 'Press Y(es) to loop or N(o) to exit.$'

What can I improve?

I added 'cli' because at the moment I think that it will not wait to check without it. Necessary or should I remove that line?

(Also, if you read this Dex, thanks for that link to the tutorial.)

Thank you,

- Steve

01 Apr 2006, 22:55

Dex4u

Joined: 08 Feb 2005
Posts: 1601
Location: web

Dex4u 02 Apr 2006, 08:12

I would remove it, also i would put a upper and lower case check, just in case of cap lock etc.
Next i would do a program to get users name, age etc and then print it back with a message including there name etc ),
Then try a password input, that asks for password, stores it and loops until they give you the password.
Nice work, just keep writing a simple program a day and before you know it, you will be coding your own OS Wink

02 Apr 2006, 08:12

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 02 Apr 2006, 12:42

Steve wrote:

Hi, I decided to take a stab at a 'Get Keystroke' type program. Right now, it seems like it is completed.

Here is the code:

Code:

org 100h
use16

Main:

mov ah, 9h ; AH = 9h / INT = 21h : Print Text
mov dx, mText ; Move mText into the data register.

int 21h ; Execute 'Print Text' interrupt.

InputCheck:

mov ah, 00h  ; AH = 00h / INT = 16h : Get Keystroke

int 16h ; Get keystroke.

cli ; Disable interrupts.

cmp al, 'y' ; Check if AL holds 'y'.

je Main ; AL holds 'y', time to loop.

cmp al, 'n' ; Check if AL holds 'n'.

jne InputCheck ; AL doesn't hold 'n' so we check again.

jmp Exit ; AL holds 'n' so we jump to Exit.

Exit:

sti ; Enable intterupts again.

int 20h ; Exit interrupt.

mText db 'Press Y(es) to loop or N(o) to exit.$'

hi,

Code:

mov ah, 00h  ; AH = 00h / INT = 16h : Get Keystroke

int 16h ; Get keystroke.

cli ; Disable interrupts.

cmp al, 'y' ; Check if AL ho

this is what we say, inconsistent, you disable the interrupts, then call interrupt 16h to read the keyboard.

02 Apr 2006, 12:42

daluca

Joined: 05 Nov 2005
Posts: 86

daluca 02 Apr 2006, 20:04

i use int 16h ah=0 alot and i never use cli,it has allways work for me.
i think you can remove the jmp Exit to unlese you put more code or data
between the jmp Exit and Exit:
and you can modify the data to:

Code:

mText db 'Press Y(es) to loop or N(o) to exit.',13,10,'$'

to show the text in a new line every time.
and i think use16 is not necesary since fasm default format is 16bit
binary flat.the org 100h directive makes fasm save the output file
with com extension....although use16 dos not affect the code in this
program.

02 Apr 2006, 20:04

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