Groups > comp.sys.acorn.programmer > #1111

Re: DragASprite_Start (ARMv7)

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From	Ian Hamilton <Ian.Hamilton@AAUG.net>
Subject	Re: DragASprite_Start (ARMv7)
Newsgroups	comp.sys.acorn.programmer
Message-ID	<523a436871Ian.Hamilton@AAUG.Net> (permalink)
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Date	Wed, 30 Nov 2011 13:22:24 +0000 (GMT)
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In article <6b3a423a52.martin@bach.planiverse.com>,
   Martin Wuerthner <spamtrap@mw-software.com> wrote:
> In message <523a3825deIan.Hamilton@AAUG.Net>
>           Ian Hamilton <Ian.Hamilton@AAUG.net> wrote:

> > What limitations are there for DragASprite_Start under ARMv7? Which
> > elements need to be word aligned?

> I am not aware of any API differences caused by ARMv7. Unless stated 
> otherwise, all pointers to word sized fields or structures that 
> contain word sized fields at word aligned offsets need to be word 
> aligned on entry to any RISC OS SWI on any processor.

> ARMv7 does not make any difference. Earlier processors could not read 
> a word sized field from an unaligned address using a single load 
> instruction either, so it never made sense to have unaligned pointers 
> to word sized fields.

I've just discovered the cause of the problem. I'm using Mode 28 sprites
and it was crashing on some drags but not others. I initially thought it
might be related to word alignment. 

It turns out a few of the sprites had palettes and it's dragging those
which crash. I've removed the palettes and the problem appears to be
resolved. 

Ian

-- 
Ian Hamilton (Iyonix/ARMini) http://www.hamiltoni.pwp.blueyonder.co.uk/

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Thread

DragASprite_Start (ARMv7) Ian Hamilton <Ian.Hamilton@AAUG.net> - 2011-11-30 11:19 +0000
  Re: DragASprite_Start (ARMv7) Martin Wuerthner <spamtrap@mw-software.com> - 2011-11-30 14:09 +0100
    Re: DragASprite_Start (ARMv7) Ian Hamilton <Ian.Hamilton@AAUG.net> - 2011-11-30 13:22 +0000

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