6 Aug
2008
6 Aug
'08
10:46 a.m.
On Wed, Aug 06, 2008 at 01:25:40PM -0400, Paul Koning wrote:
By the way, I meant to mention another compiler that
did something
like P-code: RT-11 Fortran. The actual scheme was called "threaded
code" because it was basically a stream of function pointers. (Come
to think of it, that's a common Forth encoding as well.) That's about
as fast as straight code if most of what you need is calls to support
functions, and more compact because you're not including the opcode
word.
That scheme sort of reminds me of FORTRAN IV for the PDP-8 - IIRC, the
compiler produces, mostly, a stream of FPP instructions that either get
executed by a real FPP-12 (or FPP-8?) _or_, lacking math hardware, get
emulated by wads of PDP-8 instructions.
The difference is rather than a stream of function pointers, it's a
stream of math co-processor instructions that are either executed by
real hardware or by an emulator library. In either environment, though,
the object code is the same.
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 6-Aug-2008 at 17:40 Z
South Pole Station
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Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html