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Postings from August 2001
Re: Opcode Dispatch
From: Dan Sugalski
August 6, 2001 08:38
Re: Opcode Dispatch
Message ID: firstname.lastname@example.org
At 01:47 AM 8/6/2001 -0400, Bryan C. Warnock wrote:
>Okay, next set of results.
>508 opcodes, arranged in a primary set of 255, and a secondary set of 253.
>The primary set contained the escape opcode (opcode 0), the null opcode
>(opcode 254), and the program termination opcode (opcode 255). The
>secondary set was mapped onto opcodes 1 - 254. (The opcodes themselves
>mapped onto the same set of 255 functions - the data, however, precluded
>calling the escape opcode from within an escaped opcode, and there was only
>one termination opcode present.) Each of 254 distinct functions were one of
>7 randomly generated code sets, each of which consisted of code that was
>essential to the final output. Functions 0 and 255 handled the secondary
>dispatch and the program termination, respectively.
Oh, right, one other thing.
We're going with a straightforward opcode numbering scheme. Opcodes get
numbered from 0 to N, where N is a number larger than 0. :) The
'predefined' opcode numbers will be guaranteed regardless of where you are
in your code. The rest will be switched in lexically. (Odds are they'll all
be switched in lexically in one big table, but that's an implementation
Opcodes above a certain point, like perhaps 512 (don't hold me to this
number), will be designated as 'noncore'. That'll mean a potential gap
between the guaranteed and non-guaranteed opcodes, but that's fine, we can
cope. We're all clever. We will guarantee that overridable opcodes will be
looked up via the opcode table, but we won't guarantee the same thing for
non-overridable ones. (Even if you can some places)
If someone/thing wants to put in an escaping mechanism, that's keen, but it
does mean that all the escaping details will be handled by something other
than the core.
--------------------------------------"it's like this"-------------------
Dan Sugalski even samurai
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teddy bears get drunk