From fnaumann@mail.cs.uni-magdeburg.de  Tue Dec  2 13:56:33 2003
To: =?iso-8859-1?q?=D6rn_Hansen?= <orn.hansen@swipnet.se>
Cc: mint_list <mint@fishpool.com>
Subject: Re: [MiNT] bug found
References: <200312020512.18959.orn.hansen@swipnet.se>
From: Andreas Schwab <schwab@suse.de>
X-Yow: I love FRUIT PICKERS!!
Date: Tue, 02 Dec 2003 13:51:44 +0100
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Örn Hansen <orn.hansen@swipnet.se> writes:

> Hey,
>
>   I've been searching for hours for why the arp protocol doesn't work as it's 
> supposed to. And finally, I found it.  The answer is in bzero, or rather 
> quickzero function in the CVS tree.
>
> loop:
> 	movem.l	d1-d7/a1,(a0)		| zero the memory, 32 bytes at a time
> 	movem.l	d1-d7/a1,32(a0)
> 	movem.l	d1-d7/a1,64(a0)
> 	movem.l	d1-d7/a1,96(a0)
> 	movem.l	d1-d7/a1,128(a0)
> 	movem.l	d1-d7/a1,160(a0)
> 	movem.l	d1-d7/a1,192(a0)
> 	movem.l	d1-d7/a1,224(a0)
> 	lea	256(a0),a0
> 	dbra	d0,loop
> 	movem.l	(sp)+,d1-d7/a1		| restore regs
> 	rts				| and leave
>
>   There are 8 registers used, and each register is 32bits, or 4 bytes in size.  
> That makes a total of 32 bytes as stated in the first line.  But notice, the 
> loading of the next effective address.  It's thinking 256 bytes at a time.

Yes, 32 * 8 == 256.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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