Re: Assembler or machinecode. Was Re: [colorforth] New Linux 4word

You know, bootsectors etc. can be written in forth if you compile
16-bit code (one block different) and just insert a hard jump

On Apr 8, 2005 5:16 PM, Albert van der Horst <[email protected]> wrote:
> On Fri, Apr 08, 2005 at 08:39:08AM -0700, Jeff Fox wrote:
> <SNIP>
> >
> > > An assembler is the proper starting point. There is no Metacompiler
> > > without assembler. And an assembler may be enough.
> > > Unless of course you think you have a nice source if it is sprinkled
> > > with
> > >         cd45 2,      12 1, 3135 2,
> >
> > I heard Chuck talking about this a couple of days ago.  He said that
> > he had always written a target assembler in Forth because it only
> > took a block or two in most cases. Then he would write the assembler
> > portion of CODE words or a kernel using the assembler so that it
> > would provide more meaningful code representation to the programmer.
> 
> I think this is attainable even for the Pentium.
> 
> > He said that the Pentium assembler was such a mess, and so complex,
> > and that he used so few of the Pentium instructions anyway that it
> > just worth the effort to provide a full high level Pentium assembler
> > for his needs in colorforth.   He added that there were so many
> > instructions and address modes etc. that people would need to have
> > a book in front of them anyway to look up opcodes to see what they
> > actually did.  So given that he needed only a few Pentium codes,
> > and assuming that most readers haven't memorized the entire Pentium
> > instruction set, or that the variation of the syntax that Chuck
> > would use in a RPN assembler would be completely obvious to readers
> > he didn't add a layer of Pentium opcode names.  He said, you are
> > going to have to go look them up anyway to understand that level
> > of the programming.
> 
> Even so. I managed to get the whole of the Intel Pentium Assembler
> down to 13 screens. The full content (316 pages) of chapter 25
> of the Intel Pentium architecture Manual is under control.
> The whole shit: the sib byte, all addressing modes, prefixes,
> 16 bits stuff in 32 bits mode and floating point.
> (This is not a RPN assembler, but a new principle PostIt FixUp,
> it is more modular.)
> 
> Now if I could trim that to the needs of colorforth, this would
> be say 5 screens. Floating point for instance now takes 3 screens,
> these could be dropped immediately.
> Even a target of 2 or 3 screens seems reasonable.
> 
> I have done a conversion of retroforth, that is in many respects
> similar to colorforth. The 1, 2, 3, thingies are automatically
> replaced by assembler instructions.
> 
> > He added that after bootstrapping then he was in a position to
> > do the normal thing of coding a Forth version that won't need
> > a kernel in assembler to get going.  It was just a matter of
> > priorities.
> 
> I can understand that it is not Chucks priority to do the kind of
> research into Intel that I have done. But I would be glad to
> share any useful techniques that I have found.
> There is no escape: it is either machine code in the kernel or
> assembler. I'm convinced that my assembler is preferable over
> machine code in the context of colorforth.
> 
> Then there are occasionally useful words in the Pentium
> instruction set like RDTSC, (read time stamp counter).
> (I use that one quite a lot.)
> 
> <SNIP>
> 
> > Best Wishes
> 
> More information :
> google for "Intel Pentium assembler".
> My site comes up first!
> 
> Groetjes Albert
> 
> --
> Albert van der Horst,Oranjestr 8,3511 RA UTRECHT,THE NETHERLANDS
> Economic growth -- like all pyramid schemes -- ultimately falters.
> [email protected] http://home.hccnet.nl/a.w.m.van.der.horst
> 
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-- 
Chris Walton
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