28 Sep
2004
28 Sep
'04
11:40 a.m.
Rumor has it that David V. Corbin may have mentioned these words:
Why not? Some of us aren't "in the trenches" so to speak WRT newer software
& languages.... I would be interested to know which platform that actually was!
>>
>>>
>> Can you create self modifying code in any high level
>> language, the kind of code where the application program
>> actually changes it's own instructions?
>>
>> I know in C it is possible to pass an address of a function
>> to a function, that's not really what I mean.
>>
Actually this is (sort of) becoming more common. One exciting feature of a
new platform by the software vendor who shall not be named, is that the compiler is actually part of the runtime.
So, in other words... it's an interpreter. Novel idea, that! ;-P
This means that any program can
write source code to a string (or other structure) and compile and execute
it!!!!!!
Lots of languages have eval() nowadays... most people think the use of it
is as evil as self-modifying code.
Dunno, if you ask me -- it sounds like "yet another gaping security hole
waiting to happen" to me...
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger --- sysadmin, Iceberg Computers
Recycling is good, right??? Randomization is better!!!
If at first you don't succeed, nuclear warhead
disarmament should *not* be your first career choice.
28 Sep
28 Sep
4:23 p.m.
I month or so ago I prattled on about what I recalled about the BTI
Computer Systems architecture, where I worked for a year back in 85/86.
That machine had an instruction to execute an instruction that was held
in a register! Kind of like the perl exec() function, for one
instruction. I imagine it could have been useful for single stepping
and other debugging operations.
5:23 p.m.
I month or so ago I prattled on about what I recalled
about the BTI
Computer Systems architecture, where I worked for a year back in 85/86.
That machine had an instruction to execute an instruction that was held
in a register! Kind of like the perl exec() function, for one
instruction. I imagine it could have been useful for single stepping
and other debugging operations.
ITYM "eval"
--
---------------------------------- personal: http://www.armory.com/~spectre/ --
Cameron Kaiser, Floodgap Systems Ltd * So. Calif., USA * ckaiser(a)floodgap.com
-- Look busy. Jesus is coming soon. -------------------------------------------
9:19 p.m.
That machine had an instruction to execute an
instruction that was held
in a register! ...
Another set of memories from vaious 3rd gen machines ...
All three of ICT 1900, IBM 360, Honeywell Level 66 (=6000) have instructions
to obey the instruction at <memory address> which, at the time they were
designed, must have seemed a way of getting the benefits of
self-modification without the problems.
IBM's EX and ICT's OBEY both were simple (indexed) instructions - Honeywell,
of course, also did something* too clever to the target instruction.
* I forget what ... but then I only wrote two small modules in assembler for
our L66 - everything else I did on that machine was either in Fortran or B.
Andy
29 Sep
29 Sep
4:27 a.m.
>>>> "Jim" == Jim Battle
<frustum(a)pacbell.net> writes:
Jim> I month or so ago I prattled on about what I recalled about the
Jim> BTI Computer Systems architecture, where I worked for a year
Jim> back in 85/86.
Jim> That machine had an instruction to execute an instruction that
Jim> was held in a register! Kind of like the perl exec() function,
Jim> for one instruction. I imagine it could have been useful for
Jim> single stepping and other debugging operations.
So did the PDP-10, back in the 1970s (and, probably, the PDP-6 -- mid
1960s.) Somewhat useful for stepping, though a "single step"
processor flag (as in the PDP11) is better because it covers branches
too.
paul
7232
days inactive
7233
days old
4 comments
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participants (5)
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andyh＠andyh-rayleigh.freeserve.co.uk -
frustum＠pacbell.net -
pkoning＠equallogic.com -
spectre＠floodgap.com -
zmerch＠30below.com