ASSEMBLY Programming..
Author:
jack
03 12th, 2010 in
sbbbs.com
edit
In C programming...
#include
main()
{
clrscr();
}
Try the following code which uses BIOS interrupts: PUSHA ; save register content
XOR EAX, EAX ;clear
XOR EBX, EBX ;clear
XOR ECX, ECX ;clear
XOR EDX, EDX ;clear
MOV AH, 6 ; use subfunction 6 of int 10h
MOV DX, 174fh ; size to clear (changes depending on screen size)
INT 10h ; call interrupt
POPA ; restore registers
Remember you can't use the BIOS interrupts in protected mode.
Let me know how you go.
Cheers
It could be the protected mode thingy I was talking about. If i can see your code then I can help you with the issue.
Never assume ;) There's more knowledge here in this area than you think.
lairusi: what architecture are you writing your ASM for? x86? x64? What assembler are you using? TASM/FASM/etc?? Are you using Windows or Linux?
try
http://www.codeguru.com/forum/forumdisplay.php?f=69
; clear the screen
mov ah, 6 ; Use function 6 - clear screen
mov al, 0 ; clear whole screen
mov bh, 7 ; use black spaces for clearing
mov cx, 0 ; set upper corner value
mov dl, 79 ; coord of right of screen
mov dh, 24 ; coord of bottom of screen
int 10h ; go!and to set the cursor to the top left of the screen use:; move the cursor to the top of the screen
mov ah, 2 ; use function 2 - go to x,y
mov bh, 0 ; display page 0
mov dh, 0 ; y coordinate to move cursor to
mov dl, 0 ; x coordinate to move cursor to
int 10h ; go!Try putting those two snippets in your own application and see how you go.
YAAAAAAAAAAAAAAAAAAAAAY!!!!!!!!
*MEXICAN WAVE*
I am so unbelievably impressed that this was at least attempted with an answer..... Well Done!:beam:
I have tried to copy pasted the code in the notepad and assembled it the same way as it is in the earlier post and it returns, clearscreen.asm:6: error: parser: instruction expected
Thank you very much for your patience.. :)
Sorry, I might have been wrong with my instructions in the previous post. I had a quick play with some ASM to make sure that I didn't mislead you again. Here's a sample program written for FASM, it clears the screen as you'd expect:
; fasm example of writing 16-bit COM program
org 100h ; code starts at offset 100h
use16 ; use 16-bit code
display_text = 9
; fill the screen with some crap
mov ah, display_text
mov dx, hello
int 21h
int 21h
int 21h
int 21h
int 21h
int 21h
int 21h
int 21h
int 21h
; clear the screen
mov ah, 6 ; Use function 6 - clear screen
mov al, 0 ; clear whole screen
mov bh, 7 ; use black spaces for clearing
mov cx, 0 ; set upper corner value
mov dl, 79 ; coord of right of screen
mov dh, 24 ; coord of bottom of screen
int 10h ; go!
; move the cursor to the top of the screen
mov ah, 2 ; use function 2 - go to x,y
mov bh, 0 ; display page 0
mov dh, 0 ; y coordinate to move cursor to
mov dl, 0 ; x coordinate to move cursor to
int 10h ; go!
int 20h
hello db 'Hello world!',24h
The code will be slightly different for you using NASM, but the core of it (the clear screen and moving the cursor back to the top of the screen), should be exactly the same.
Hope that helps
Try the following code which uses BIOS interrupts: PUSHA ; save register content
XOR EAX, EAX ;clear
XOR EBX, EBX ;clear
XOR ECX, ECX ;clear
XOR EDX, EDX ;clear
MOV AH, 6 ; use subfunction 6 of int 10h
MOV DX, 174fh ; size to clear (changes depending on screen size)
INT 10h ; call interrupt
POPA ; restore registers
Remember you can't use the BIOS interrupts in protected mode.
Let me know how you go.
Cheers
Thank you for your reply Colonial.. And apologies for my late reply... I have tried your code and unfortunately (or I think) it's not working... Did I do something wrong?
I run command prompt then, typed the ff. to assemble the code:
nasm -o fibo.com -f bin fibo.asm
then after compiling,
i typed fibo. Then, it produced
http://img379.imageshack.us/img379/7366/errorwe1.png
In C programming...
#include
main()
{
clrscr();
}
This is probably the the single hardest question I've ever seen in a forum :hugegrin:
You haven't mentioned what platform you are using, which makes this question impossible to answer. ASM is CPU specific, which means that although most opcodes/mnemonics are basically the same, the subtle differences that are there, will most likely kill any none specific implementation.
Roughly:
First you need to figure out a way to get access to the memory dump off the screen. This depends heavily on what platform you are working on.
Once you have the address of the screen data, its just a question about writing zeros to it.
But seriously though ... i rather doubt you will be able to write an asm function that is more efficient than the above C code yourself, so why bother ;)
Thank you very much!!!! :bounce:
lairusi: what architecture are you writing your ASM for? x86? x64? What assembler are you using? TASM/FASM/etc?? Are you using Windows or Linux?
I'm using Windows. NASM, x86, 32-bit. I hope I answered your questions correctly. =) I'm still grasping the concept of this programming language.
Thanks!
I'd just like to say that I highly recommend reading that code over and over until you understand what's going on. There's plenty of documentation on the Internet about the interrupts that you're using, and you should make sure that the code makes sense. There are comments there to help you understand. Promise me you'll make the effort to do that, because code regurgitation is a bad thing if you don't understand what's going on! :)
Good luck with the rest of your project.
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