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From: chuck@dartvax.UUCP (Chuck Simmons)
Newsgroups: net.puzzle
Subject: Short sequences of assembly language instructions
Message-ID: <3256@dartvax.UUCP>
Date: Sun, 16-Jun-85 02:24:12 EDT
Article-I.D.: dartvax.3256
Posted: Sun Jun 16 02:24:12 1985
Date-Received: Tue, 18-Jun-85 05:20:12 EDT
Distribution: net
Organization: Dartmouth College, Hanover, NH
Lines: 12

The following 5 instruction routine is written in 68000 code.
What does it do?  

; D0 and D1 are 32 bit registers.

    move.l d0,d1          ;     d1 := d0
    bra.s L2              ;     goto L2
L1: sub.l d1,d0           ; L1: d0 := d0 - d1 
L2: lsr.l #1,d1           ; L2: d1 := d1 div 2
    bne.s L1              ;     if d1 <> 0 then goto L1

Cheers, Chuck