Making a Maze Game in MASM

jschmuff
jschmuff used Ask the Experts™
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I have been messing around with MASM for some weeks now and I want to try and make something that would interest me like a game. So I thought I wanted to make a Maze game. Not sure on size yet I want to see what my default console shows first. Can I get some suggestions on where to start, or if there is any tutorials out there on this or maybe some examples I could take a look at?
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Top Expert 2009

Commented:
Although not necessarily dealing with MASM specifically, I can still recommend "The Art of Assembly Language" as a great introduction to assembly language programming :

        http://webster.cs.ucr.edu/AoA/index.html

Author

Commented:
I currently have a Assembly Language for Intel Based Computers already that I have been using, I wouldn't want to get another book really if I don't have to.

Author

Commented:
Ok I would say this how can I display multiple characters on the screen without making a gotoxy macro then telling what character to write to the screen for every single character space. something that is easy I guess or the best way to do it.I think that is where I should probably start I would then think I would create boundaries after that and create the "character" character say a # is the character, then probably take in input from the user like using the arrows keys. But that is all in the future I just want to be able to display all the walls without typing 1000's of lines of code  or even 100's because I dont know the efficient way to do it.
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Top Expert 2009
Commented:
All except for the published edition of the book are freely available for download or consulting on the site I mentioned.

For specific MASM information, you can check the MASM reference :

        http://msdn.microsoft.com/en-us/library/afzk3475.aspx

And the MASM forum is probably also useful :

        http://www.masm32.com/board/index.php

I'm sure if you google for "MASM tutorial", you can find one that you like - I won't recommend any, because I haven't read any ;)
Top Expert 2009

Commented:
>> I just want to be able to display all the walls without typing 1000's of lines of code  or even 100's because I dont know the efficient way to do it.

What if you store the wall layout in a set of strings (one for each line), and then display all these strings one by one ?

Author

Commented:
I could do that, but I need to create some sort of collision for the walls so I cannot just move there, but I am getting way ahead I need to draw a character to the screen and take movement input from the user. Any simple way to do that? I suppose not ASM doesn't seem to be simple at all.
Top Expert 2009

Commented:
>> I could do that, but I need to create some sort of collision for the walls so I cannot just move there

That's not a problem, since you can recognize where the walls are, and cause a "collision" whenever you try to move into a wall.
The strings are only used for output-ing the walls onto the screen. You can use any variation you prefer to support the features you need, but the idea is to keep a buffer in memory that represents the entire screen, and simply write that buffer to the screen when you need to (with a simple loop).


>> I need to draw a character to the screen and take movement input from the user. Any simple way to do that?

drawing something or getting input usually requires system calls. It depends on your specific platform and your specific dialect of ASM. From your question, that seems to be MASM on DOS.

What you'll need, is the 'int 21h' interrupt, and probably these options/commands :

        01 : get character from inpu with echo (AH = 1, AL will contain read character)

                   mov ah, 1h
                   int 21h

        02 : to display a character (AH = 2, DL = ASCII character)

                   mov dl, 'A'
                   mov ah, 2h
                   int 21h

        09 : display a string (AH = 9, DS:DX = pointer to $ terminated ASCII string)

                   .data
                   str db "STRING", 13, 10, $

                   <SNIP>

                   mov ax, @data
                   mov ds, ax
                   mov dx, offset str
                   mov ah, 9h
                   int 21h

There are many more interrupts. For more information, just look up int 21h.

Author

Commented:
Any time I try and use interrupts the program bombs on me as soon as the program gets to that portion of the code. For example,

;wait for any key to get pressed
mov ah,0
int 16h

as soon as the programs executes those instructions in bombs out. I am using AMD Athlon XP X2 6400+ on Windows Vista Ultimate 32-bit. This is also using MASM if that makes a difference.
Top Expert 2009

Commented:
Try the int 21h interrupts I mentioned.

I'm not sure whether the int 16h would work from Windows. From DOS it should, but when booted into Windows, I would assume the OS blocks attempts to access the BIOS.

If the int 21h interrupts don't work either, then it's possible that Vista has some more "protection", although I'd doubt that, because they are at the core of pretty much any application.

Author

Commented:
Same int 21h bombs my program as well the minute it try and executes the interrupt it bombs out. So we have to start over from scratch here on your example of what I could do.
Top Expert 2009

Commented:
Well, that means that your OS doesn't allow you direct access using the interrupts. So, you'll have to call Windows API functions instead. You can check MSDN for the available Win32 API functionality, and how to make use of it.

Author

Commented:
Ok so I know this isn't completely right but for now I am mainly trying to work on movement so I drew a hypothetical maze using a macro I have made for writing to the console. I can't seem to get it to work right and my lack of knowledge is making it hard for me to see the problem here, any help?

Right now the loop ends for somereason even though the if statement isn't true, and because of that my character isn't moving, I know where it is at right now it should leave a trail of _char until I create a cleanup method as well. For now I just wanna get the loop working right and the _char to move around which is a square 0DBh is the hex for it.

Here is my main code and variables:
_x BYTE ?
_y BYTE ?
_char BYTE 0DBh
_move DWORD ?
 
;*****************GAME LOOP*********************
DRAW:
	mWrite "#################X##"
	mWrite "################  ##"
	mWrite "################ ###"
	mWrite "###########      ###"
	mWrite "########### ########"
	mWrite "########### ###   ##"
	mWrite "########### ### ####"
	mWrite "###########     ####"
	mWrite "############ #######"
	mWrite "####         #######"
	mWrite "############ #######"
	mWrite "############ #######"
	mWrite "############ #######"
	mWrite "############ #######"
	mWrite "#######      #######"
	mWrite "####### ############"
	mWrite "        ############"
	mWrite "####### ############"
	mWrite "#######         ####"
	mWrite "####################"
	
	mov _x, 0
	mov _y,16
	JMP GAME
GAME:
	call readstring
	mov _move, eax
	call writeint
	mGotoxy _x, _y
	mov al, _char
	call writechar
	.if _move == 119 ; UP
	dec _y	
	.endif	
	.if _move == 115 ; DOWN
	inc _y
	.endif	
	.if _move == 97 ; LEFT
	dec _x
	.endif	
	.if _move == 100 ; RIGHT
	inc _x
	.endif
	
	.if _x == 1 || _y == 1
	JMP OVER
	.endif
 
	JMP GAME
    
;*****************END GAME**********************
OVER:
    
	exit

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Top Expert 2009

Commented:
>>         .if _x == 1 || _y == 1

Isn't the game over when the player reaches _y == 0 ?


You'll also need to add collision logic (when the player bumps into a wall), but I assume you plan to add that once the movement works.

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