Assembly Language

gamblitis

I'm currentyl doing an assignment where i have to print a 4x4 grid of random numbers 1-16.Each has to be included once i just need them in random order in the grid.

Its the golden board problem if anyone recognises it.

I've tried printing them out individually but i exceed the range i can jump with my repeat question at the end.

Is ther any way i can create a grid and if so how do i access each individual block to place contents in?

Any help much appreciated.
Cheers

gamblitis

Can anyone help me out at all?

stylers

why the title "Assembly language" ??, and no reference to it afterwards . you'll really have to give more info about the problem than that for anyone to help..

Evil Phil

And post some code if you don't want the thread locked. You'll never learn anything if you get other people to do it for you.

gamblitis

.model small
.data

	CR equ 13
	LF equ 10
	
	message1 db CR,LF, "1     $"
	message2 db "2     $"
	message3 db "3     $"
	message4 db "4$"
	message5 db CR,LF, "5     $"
	message6 db "6     $"
	message7 db "7     $"
	message8 db "8$"
	message9 db CR,LF, "9     $"
	message10 db "10    $"
	message11 db "11    $"
	message12 db "12    $"
	message13 db CR,LF, "13    $"
	message14 db "14    $"
	message15 db "15    $"
	message16 db 5fh
	blankline db CR,LF, "$"
	digitpress db CR,LF, "To print again press 'r': $"
	
.code
stack 100h
	
Program:

	call initsegs
start:
	mov dx, OFFSET message1
	call print
	mov dx, OFFSET message2
	call print
	mov dx, OFFSET message3
	call print
	mov dx, OFFSET message4
	call print
	mov dx, OFFSET message5
	call print
	mov dx, OFFSET message6
	call print
	mov dx, OFFSET message7
	call print
	mov dx, OFFSET message8
	call print
	mov dx, OFFSET message9
	call print
	mov dx, OFFSET message10
	call print
	mov dx, OFFSET message11
	call print
	mov dx, OFFSET message12
	call print
	mov dx, OFFSET message13
	call print
	mov dx, OFFSET message14
	call print
	mov dx, OFFSET message15
	call print
	xor ax, ax
	mov al, message16
	mov dl, al
	mov ah, 02h
	int 21h
	mov dx, OFFSET digitpress
	call print
	xor ax, ax
	int 16h
	mov bl, al
	cmp bl, 'r'
	je start
        call eXit

;--------------------Exit-----------------------------------
PROC eXit
		PUSH ax
		mov ax, 4c00h
		int 21h
		POP ax
	ret
ENDP eXit
;--------------------EndExit-----------------------------------
;-------------Print------------------------------------
PROC print
		Push ax
		mov ah, 9
		int 21h
		Pop ax
	ret
ENDP print
;----------EndPrint-------------------
;--------------------------Initsegs---------------------------------
PROC initsegs
		mov ax, @data
		mov ds, ax
	ret
ENDP initsegs
;----------------------EndInitSegs-------------------------------------------


END Program

This what i have so far. This prints out the grid containing 1-16 in sequence.But what i need is for them to be printed out in a random order.`Pressing r repeats the print out but the randomisation thing is getting me.

seamus

You're looking for a random number generator.

Assembly language doesn't come with pseudo-random generating functions, so I'm going to assume that's the primary reason why you've been given the task, so I'm not going to give you the answer. Google will give the same answer I was going to anyway.

Rather than trying to pick a number and then insert into a random point in the grid, it would make more sense to pick a random number, then place that in the first spot in the grid. Then pick another random number, make sure it hasn't already been picked, and place it in the second spot on the grid, and so on...

carveone

seamus wrote: »

You're looking for a random number generator.

Yes indeedy. Google for it. In fact, given that I'm so old, I can remember that this might be a Usenet comp.lang.asm FAQ. Use the FAQ Luke... Or, given that you're probably in a University, Knuth's "Art of Computer Programming". This may involve going to a "library" (I know, I know, it's a tough life).

Hum. Here's a silly solution off the top of my head (i'm suddenly moved to creativity). Take a number (call it the seed" and multiply it by another largish number. Store it back in the seed. Very hard. I mean, you have 10 numbers to shuffle, you aren't creating DES or something.

.data
rseed dw ?

.code

rand:
mov ax,word ptr [rseed]
mov dx, 9876h
mul dx
inc ax
mov word ptr [rseed],ax
ret

(random returned in ax)

I'll leave it up to you how to get ax to be a number from 1 to 10...

Rather than trying to pick a number and then insert into a random point in the grid, it would make more sense to pick a random number, then place that in the first spot in the grid. Then pick another random number, make sure it hasn't already been picked, and place it in the second spot on the grid, and so on...

Oooh, a bit brute force but hey, this will work for 10 numbers. Eventually. It wouldn't be good idea for 1000 numbers though. More algorithms (see library above) or take 10 numbers in an array and shuffle them...

Webmonkey

Amn't sure if will help or not, might be a bit too complex for just this case.

Linear Freedback Shift Registers
http://en.wikipedia.org/wiki/Linear_feedback_shift_register
http://www.diycalculator.com/docs/demo-lfsr.pdf

Tobias Greeshman

seamus wrote: »

You're looking for a random number generator.

The most simplistic of random number generators tend to get a the current system time and multiply it by a large value. As the system time tends to always return something different this guarantees a certain degree on random.

If you're doing this on Windows, the Dos "int 21h" set of functions should provide a mechanism for getting the system time. A quick search on google for the "int 21h" reference of functions should tell you how to do this.