Re: Purify patent (was Re: gawk memory leak)

Sailesh Krishnamurthy wrote:
>
> Paul David Fox wrote:
> >> I did some research into the Purify patent. There are
> >> actually 3 inter-related ones. I havent got the reference
> >> to hand but the substance of the patent is 'Use of object
> >> code modification to facilitate memory tracking and
> >> leakage detection'.


Anthony V. Ingenoso and I wrote a simple one of these in 1984 at the New
Technology Division of Interactive Data Corp, Waltham, MA. I am
surprised someone obtained a patent on somthing like this.


It was called the Pointer Checker and inserted bounds checks for FAR
pointer stores for Lattice C 2.5 object files. FAR writes and RMWs were
recognizable by their ES segment overrides. As a bonus it generated
optimized (packed and threaded) object files.


The reaching code walker had to understand the 3 different forms of
"switch" statements in order to walk the "case" branch tables embedded
in the code segments. It was a nice utility and saved the C programmers
a lot of debugging time. This right around the time of the PCAT and DOS
3.x.


I wanted inline checks, but Tony opted for out of line which eliminated
motion of the surrounding code.


-Duncan Smith
Flavors Technology, Inc.
[Software patents are a notorious morass, and one of the worst problems is
that the patent office completely unfamiliar with the prior art. -John]


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