A nice quick small random numbers routine?

Photon · 20 December 2004, 20:34

Hi!

Wrote a routine to generate random numbers (0-65535). I start with a weird number for seed, I eor that with another weird number that changes for each time. Then I save the new seed, take it, divide by a weird number and take the modulo. I thought that would confuse it enough to make nice random numbers, but when I plot them a pattern shows up (the same number comes up several times in the number table).

Anybody have a nice little Really Random Number Generator (in 68000 Assembler of course)?

In that case, please share thy knowledge!

Codetapper · 20 December 2004, 21:07

Dunno how random this code is but I've seen it (or variants of it) in quite a few Amiga programs. Give it a try anyway:

Code:

_RandomWord	bsr	_RandomByte
		rol.w   #8,d0
_RandomByte	move.b  $dff007,d0
		move.b  $bfd800,d1
		eor.b   d1,d0
		rts

Obviously d0 contains the "random" word after it's finished, d1 is destroyed.

lloyd · 20 December 2004, 21:56

May be able to supply something in Z80.... Is it easy to convert Z80 assembler to 68K? Never tried 68K so wouldn't know.

20 December 2004, 20:34	#1
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	A nice quick small random numbers routine? Hi! Wrote a routine to generate random numbers (0-65535). I start with a weird number for seed, I eor that with another weird number that changes for each time. Then I save the new seed, take it, divide by a weird number and take the modulo. I thought that would confuse it enough to make nice random numbers, but when I plot them a pattern shows up (the same number comes up several times in the number table). Anybody have a nice little Really Random Number Generator (in 68000 Assembler of course)? In that case, please share thy knowledge!

20 December 2004, 21:07	#2
Codetapper 2 contact me: email only! Join Date: May 2001 Location: Auckland / New Zealand Posts: 3,182	Worth a try Dunno how random this code is but I've seen it (or variants of it) in quite a few Amiga programs. Give it a try anyway: Code: _RandomWord bsr _RandomByte rol.w #8,d0 _RandomByte move.b $dff007,d0 move.b $bfd800,d1 eor.b d1,d0 rts Obviously d0 contains the "random" word after it's finished, d1 is destroyed. Last edited by Codetapper; 20 December 2004 at 21:14.

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20 December 2004, 21:56	#3
lloyd Mehh :D Join Date: Nov 2004 Location: Bristol, SW UK Age: 61 Posts: 242	May be able to supply something in Z80.... Is it easy to convert Z80 assembler to 68K? Never tried 68K so wouldn't know.

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