Article View: comp.arch
Article #22110Re: RISC Machine Data Structure Word Alignment Problems?
From: Peter da Silva
Date: Thu, 01 Feb 1990 18:37
Date: Thu, 01 Feb 1990 18:37
22 lines
1629 bytes
1629 bytes
In article <3428@odin.SGI.COM> pkr@maddog.sgi.com (Phil Ronzone) writes:
> No, I disagree. Most of the time the data (mis)alignments are from real world
> constraint. Compressed video data, even when capacious CD-ROMs are used, are
> full of adjacent 1, 2, 3, and 4 byte integer
And ajacent 4-, 5-, 6-, and 12- bit integers as well. I've heard of bit
addressible memory, but outside of microcontrollers I've never actually
seen it.
> And generally you want to
> read and display that data as fast as is possible. Having a microcoded
> unaligned data capability is faster than user-level instructions doing the
> same thing.
If your loop is in an instruction cache you'll probably find that your
actual memory accesses are coming as fast as the bus can fill them. Cutting
the size of your loop will just add wait states.
--
_--_|\ Peter da Silva. +1 713 274 5180. <peter@ficc.uu.net>.
/ \
\_.--._/ Xenix Support -- it's not just a job, it's an adventure!
v "Have you hugged your wolf today?" `-_-'
Technical Details
Message-ID:
<4YG1638xds13@ficc.uu.net>Path:
arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!wuarchive!texbell!sugar!ficc!peterReferences:
<111@melpar.UUCP> <1990Jan21.224826.1699@esegue.segue.boston.ma.us> <S4B1L47xds13@ficc.uu.net> <1871@l.cc.purdue.edu> <KMD168Axds13@ficc.uu.net> <3428@odin.SGI.COM>Show Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!wuarchive!texbell!sugar!ficc!peter From: peter@ficc.uu.net (Peter da Silva) Newsgroups: comp.arch Subject: Re: RISC Machine Data Structure Word Alignment Problems? Message-ID: <4YG1638xds13@ficc.uu.net> Date: 1 Feb 90 18:37:38 GMT References: <111@melpar.UUCP> <1990Jan21.224826.1699@esegue.segue.boston.ma.us> <S4B1L47xds13@ficc.uu.net> <1871@l.cc.purdue.edu> <KMD168Axds13@ficc.uu.net> <3428@odin.SGI.COM> Reply-To: peter@ficc.uu.net (Peter da Silva) Organization: Xenix Support, FICC Lines: 17