How to generate random numbers in ASM

[Blue]

Hi guys,

I am coding a new project in assembly (using MASM). I need to generate a random number each time that exe will run.

To be more clear i need to generate random numbers between 0 to 9. I have tried crt_rand , but it gives me 1 every time I run the exe.

Do anyone have any idea or source/demo on how to generate random numbers between 0 to 9 please tell me.

And if the implementation of random function will be simple, it will be more useful.

Thanks

Blue Indian

[DizzY_D]

Hey,

I think I have what you are looking for.

I just found this source code on my disk. I dont know where i got it from but as long as it works it's ok right?

So try this one:

.586
.model flat,stdcall 
option casemap:noneTiny_Random proto :DWORD.data
TinyRNG_x   dd  0
TinyRNG_a   dd  100711433.code
start:
invoke Tiny_Random, 10				;Returns a random number from 0-9 in eax
Tiny_Random proc uses edx   iRange
   rdtsc
   adc eax, edx
   adc eax, TinyRNG_x
   mul TinyRNG_a
   adc eax, edx
   mov TinyRNG_x, eax   mul iRange
   mov eax, edx
   ret
Tiny_Random endp
end start

greetz

DizzY_D

[Killboy]

Shouldn't it be div iRange?

If you're interested, here's some background on the subject:
/>http://www.dreamincode.net/forums/topic/24225-random-number-generation-102/

Edited June 13, 2011 by Killboy

[Ufo-Pu55y]

Funnily I needed that info myself right now, so I had to dig a bit:
/>http://forum.tuts4you.com/index.php?showtopic=15474

PS: searching the board is a pita when the stuff is older than 2 years

[Blue]

@DizzY_D :

Thanks for the code, but every time I run the executable the random number is 2.

After that, i is producing random number.

But, what I need is, every time when I run my executable, a different random number will be generated.

Means that if i run my program first time,then random number will be 3, after that in second run random number will be 7 or anything like this way.

Thanks KillBoy for my support, but still not solved.

[Blue]

@DizzY_D :

Thanks for the code, but every time I run the executable the random number is 2.

After that, it is producing random number.

But, what I need is, every time when I run my executable, a different random number will be generated.

Means that if i run my program first time,then random number will be 3, after that in second run random number will be 7 or anything like this way.

Thanks KillBoy for my support, but still not solved.

//

Thanks Ufo, thats what i am looking for.

Edited June 13, 2011 by Blue Indian

[Saduff]

I use this to generate random numbers:

In the DialogProc/WinMain, if Message = WM_INITDIALOG:

invoke GetTickCount
invoke nseed, eax

The above will set the seed of the randomizer,

so each time you run the app, the first value could be different.

Now, to generate random numbers:

invoke nrandom, 9 ; will generate a random number in the range 0-9

Oh and make sure you include masm32.inc and masm32.lib.

Edited June 13, 2011 by Saduff

[ghandi]

BlueIndian, what exactly is wrong with Google and actually searching before posting on the forums????

www.google.com
/>http://www.lmgtfy.com/?q=random+number+generator+ASM
/>http://www.google.com.au/#hl=en&source=hp&q=asm+random+number+generator&oq=random+ASM&aq=1b&aqi=g-v1g-b1&aql=&gs_sm=e&gs_upl=359l2203l0l10l8l0l0l0l0l422l1593l2-3.1.1l5&bav=on.2,or.r_gc.r_pw.&fp=f134c59cefb8f2f7&biw=1291&bih=538

While i have no problems with helping people, i do get irritated every time i see a person sticking out their hand saying 'gimme' when they show not one single shred of evidence that they have even bothered to perform a search on the subject.

HR,

Ghandi

[qpt^J]

here's the example of code, that im using to generate some random numbers.

GenRandomNumbers	PROTO	:DWORD,:DWORD
Randomize		PROTO
.data
Rndm			dd	0
B32Chars		db	"0123456789ABCDEFGHIJKLMNOPQRSTUV",0
.code
GenRandomNumbers	Proc uses ebx	pIn:DWORD,pLen:DWORD
	mov edi,pIn
	mov ebx,pLen
	.repeat
		invoke	Randomize
		mov ecx,32			; Change this number to a new Alphabet size if your gonna modify it
		xor edx,edx
		idiv ecx
		movzx eax,byte ptr [edx+B32Chars]
		stosb
		dec ebx
	.until zero?
	Ret
GenRandomNumbers endp
Randomize	Proc uses ecx
	invoke	GetTickCount
	add Rndm,eax
	add Rndm,eax
	add Rndm,'abcd'
	Rol Rndm,4
	mov eax,Rndm
;	imul eax,'seed'
	Ret
Randomize endp

[Blue]

Thanks Saduff, gandhi and qpt^j for nice codes and helps.

Sorry, to gandhi. Ok brother I will keep in mind. I was in hurry so posted here.

[deepzero]

if i need a small implementation, i am using GetCurrentProcessId() and xor/ror/... it against GetTickCOunt() or RDTSC.

[Ufo-Pu55y]

I was curious some days ago, because I needed the fastest (reliable) random

function I could get (for some stuff in C actually). Of course the speed factor

isn't interesting when keygenning, but if somebody's interested in it nevertheless,

here's a radasm project to see for yourself: rand_test.7z

It compares following approaches:

1) masmlib's nrandom (stop waisting your time.. you can't top this one)

2) msvcrt's rand (just so)

3) some silly rdtsc try (omg I didn't expect rdtsc to be that slow!)

4) advapi32's CryptGenRandom (for the keygenning perfectionists (as mentioned by MOID))

cheers

\EDIT:

I forgot: for compiling the SSE ops you need at least ml.exe v6.15:
/>http://www.4shared.com/file/-QIUp-BF/ml615.html

Edited June 18, 2011 by Ufo-Pu55y

[grizzmo]

This isn't asm, but works fine in vb. You get the idea.

Dim startIndex As New String("1234567890")
Dim random As New Random
Dim startIndex1 As New String("0987654321")
Dim random1 As New Random
startIndex = random.Next(startIndex)
startIndex1 = random1.Next(startIndex1)
Dim str1 As String = startIndex
Dim str2 As String = startIndex1
Dim str3 As String = (str1 + str2).Substring(0, 10)
TextBox2.Text = str3
End SubEnd Class

Concentate the strings and extract 10 chars. Off course you can extract one char also.

Good luck.

grizzmo

Edited June 18, 2011 by grizzmo

[Blue]

@Ufo-Pu55y :

Nice coding brother, I also never expected that RTDSC is so slow

Thanks brother, nice ideas all in one

[X-88]

In Delphi :

^{Random(9); Dec}

^{IntToHex(Random(9), 2); Hex}

^Global

^var

^{I : Integer;}

^{@Form Show}

^begin

^{I := 0;}

^end;

^@Button

^begin

^{I := I + 1;}

^{ifI = 9 then}

^{I := 0;}

^end;

LoL

[mrexodia]

@X-88: how is that ASM???

[Departure]

In Delphi :

^{Random(9); Dec}

^{IntToHex(Random(9), 2); Hex}

^Global

^var

^{I : Integer;}

^{@Form Show}

^begin

^{I := 0;}

^end;

^@Button

^begin

^{I := I + 1;}

^{ifI = 9 then}

^{I := 0;}

^end;

LoL

Wtf is that lol

He asked to generate random number between 0..9 in ASSEMBLY.

And in delphi it would be a simple "Random(9)" not all that stuff you have above lol...

and if you really must you can also do RandomDigit:= Random(2147483647) mod 9; <---- i use this instead of RandomRange which requires the math unit.

Back to my point he asked for assembly and saduff suggestion seems to be the best for this situation, not to mention the fact this original post is over 1 year old

[X-88]

why not use arrays or ...

[X-88]

Randomize in Asm may be like this?....Or in ASM:	 @myLoop:		
	 mov [edx], 0
	 inc edx, 9   
	 dec ecx		
	 jnz @myLoop	 and repeat, as long as ECX is not zero.Or this:	 @myLoop:
	 mov [edx], 0
	 inc edx, 9
	 loop @myLoop

link #0

link #1

link #2

link #3

Edited June 30, 2012 by X-88

[ghandi]

What on earth are you talking about? Your code doesn't even make sense let alone generate random numbers.

1. Save ZERO to dword ptr [edx]? This means it generates NULL bytes, nothing random about 00's

2. INC doesn't take a size or count operand, it INCrements by one

3. Your loop condition of ECX is never set, so whatever value it has on entry to the loop is ???

It is all good to want to help but this is not helping at all.

HR,

Ghandi

[X-88]

What on earth are you talking about? Your code doesn't even make sense let alone generate random numbers.

1. Save ZERO to dword ptr [edx]? This means it generates NULL bytes, nothing random about 00's

2. INC doesn't take a size or count operand, it INCrements by one

3. Your loop condition of ECX is never set, so whatever value it has on entry to the loop is ???

It is all good to want to help but this is not helping at all.

HR,

Ghandi

I am not a asm programmer, so I do not know about that, that I can from the MASM forum. if you can why do not you help him or just a handyman comment?! ... I just tried to find a solution if it is wrong, because I do not understand basic code, so I do not understand the direction of the asm code.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Is not there something more ...

Edited July 4, 2012 by X-88

[ghandi]

Look, don't go getting upset at me when you are the one offering help on a subject you know nothing about.

The OP didn't ask for people to guess how to achieve their goal, if you want to randomly experiment with code then that is up to you but to offer it as a solution to a problem is ;just weird...

Once again, get off your pedestal and look at this for what it is and if you want me to offer some information aside from questioning your posts, enjoy:

http://www.agner.org/random/randoma.zip

If anybody wants to look at some random number routines aside from the ones already offered, why not go check out coding guru Agner Fog's library? It is open source and inside the linked zip file is another archive with, wait for it, the source code to the 3 random generators he rewrote in his own style and released along with their auxilliary functions, 32 bit and 64 bit:

Correct usage of RDTSC (wrap in CPUID to serialize execution)

Instruction Set Detection

VIA Physical Seed Generator

Mersenne Twister

Mother-Of-All RNG

SIMD-oriented Fast Mersenne Twister (SFMT)

The Mersenne Twister for example, has a period of 10^6001 as opposed to a lot of other RNG available that have a smaller period before repeating the cycle and this is without trying to add more 'randomization', but it would likely only end up spoiling what is already there if somebody tried to alter it blindly.

Read enough and experiment yourself and you'll realize that trying to make true randomness from a computer ranges from difficult to impossible, depending on what you read and believe.

This is the first and foremost reason that somebody who has no knowledge of either random number generation OR of the programming language that the original poster asked about should not be offering code examples or help, it is something which even seasoned coders fail on.

The point of helping is to give somebody the best chance possible, is it not? All of this is pretty much redundant anyway, you resurrected a dead post to answer it with useless information and for what, some attention?

HR,

Ghandi

Edited July 5, 2012 by ghandi

[Vovan666]

Write on base Mersenne Twister random library (not optimised)

rnd_min_max PROTO :DWORD,:DWORD ;min,max

rnd_dw PROTO ;random dword's eax,edx

rnd_hash PROTO :DWORD,:DWORD ;out,len

rnd_string PROTO :DWORD,:DWORD,:DWORD ;out,charset_table,len

random_lib.rar