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Path: utzoo!mnetor!seismo!rutgers!dayton!viper!john
From: john@viper.Lynx.MN.ORG (John Stanley)
Newsgroups: comp.sys.atari.st
Subject: Re: problems with rnd# from assembler
Message-ID: <1021@viper.Lynx.MN.ORG>
Date: Tue, 19-May-87 15:51:27 EDT
Article-I.D.: viper.1021
Posted: Tue May 19 15:51:27 1987
Date-Received: Sat, 23-May-87 04:13:50 EDT
References: <2088@pbhya.UUCP>
Reply-To: john@viper.UUCP (John Stanley)
Organization: DynaSoft Systems
Lines: 29
Keywords: midi/rnd#

In article <2088@pbhya.UUCP> gdr@pbhya.UUCP (Guy Ridley) writes:
 >
 >Does anyone have some good documentation on calling trap #17 (the random
 >number generator) from assembler?  Acc'd to what I have the rnd# generator
 >is reseeded when the machine is turned on, and calling trap #17 puts a
 >random number in D0.  However, what I seem to be getting (based on what
 >note comes out of my synthesizer, to which the contents of D0 are sent via
 >MIDI) is a lot of decimal "40"'s.  This is completely mystifying, and the
 >Assempro documentation doesn't say much more that "ST Internals" does.
 >Can anyone send me a small sample of such a call that works? 
 > 

  No, no, no...  It's xbios subfunction 17, NOT trap 17..  
(God knows what's on trap 17...)

  Try:
	move.w	#17,-(sp)
	trap	#14
	addq.l	#2,sp		* random number now in D0

  I haven't tried it, but I also haven't heard about anyone else
having problems with it, so it "should" work.  (Note:  The random
number returned is only 24 bits long so you'll only get from zero
to 16777215 ($00ffffff)...)

--- 
John Stanley (john@viper.UUCP)
Software Consultant - DynaSoft Systems
UUCP: ...{amdahl,ihnp4,rutgers}!{meccts,dayton}!viper!john