Article View: comp.arch
Article #21222Re: 80486 vs. 68040 code size (Really: No-Access bytes)
From: J.E. Dyer
Date: Fri, 12 May 1989 14:49
Date: Fri, 12 May 1989 14:49
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1574 bytes
In article <1921@se-sd.sandiego.ncr.com> lord@se-sd.sandiego.NCR.COM (Dave Lord(SSP)) writes:
>In article <3150@tank.uchicago.edu> phd_ivo@gsbacd.uchicago.edu writes:
>
>>byte? This way, one can put a single No-ACCESS byte between datastructures at
>>link/load time, which should detect out of pointer ranges much more quickly
>>than the wait-and-see in use in our systems. (At least I have spent days of my
>
> while (a[index] != 0 and index++ <= A_BOUNDS){ ... whatever ...};
The problem I see with this method is that not all array access
is sequential. For example, I might have another array which
contains the index I want to use. For example:
for (i = 0; i < A_Bounds; i++) {
x = a[b[i]];
....
}
In this case, if the value in b[i] is invalid, the chances are
that it's not going to be equal to A_Bounds, which is the only
error that a N0-access byte would detect. IMHO, parity checking
is much more valuable.
--Jason
-sig-of-the-day-
"Kludge??? That's not a Kludge, it's _ART_!"
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!cs.utexas.edu!rutgers!rochester!rit!ultb!jed4885 From: jed4885@ultb.UUCP (J.E. Dyer) Newsgroups: comp.arch Subject: Re: 80486 vs. 68040 code size (Really: No-Access bytes) Message-ID: <814@ultb.UUCP> Date: 12 May 89 14:49:45 GMT References: <3150@tank.uchicago.edu> <1921@se-sd.sandiego.ncr.com> Reply-To: jed4885@ultb.UUCP (J.E. Dyer (713ICS)) Distribution: eunet,world Organization: Rochester Institute of Technology, Information Systems Lines: 28