[A83] Re: Compiled BASIC ?
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[A83] Re: Compiled BASIC ?
This link right here:
http://compilers.iecc.com/crenshaw/
explains how to write a compiler that converts basic
to assembly with pascal source code. It is a very
long document, but I just thought it might be
interesting to some people that were considering
working on one of these compilers.
~Jeff Ruud
--- Frank Schoep <dsfs98@concepts.nl> wrote:
>
> As you might have seen, I was one of the few
> wanna-be's who tried to make
> such a precompiler/converter. Altough it seems
> fairly easy to create such a
> program, many problems arise when thinking about
> structure in the BASIC
> programs. If you take very optimized BASIC code,
> it's hard to compile it
> into anything like the original.
>
> Second problem you get is detecting when the program
> wants to write to the
> graphscreen or the homescreen - this is causing much
> trouble because you
> simply can't know all the time.
>
> Thirdly, variables are a problem. In my unfinished
> demo, you could see that
> the prog detects string and lists, but *you* must
> enter a maximal byte size
> for these things. I also made al variables like A, B
> etc... integers with
> one byte precision (0x00 to 0xFF). Also my program
> is able to extract all
> string resources (you know what I mean - all strings
> used in the program)
> and let you edit them (UPPERCASE BASIC to lowercase
> ASM).
>
> If anyone would try to make another attempt for a
> compiler/converter, I
> might be able to provide some support, but hey - I'm
> not going to try it
> again because I'm done with TI-BASIC and have many
> other things to do right
> now ;)
>
> And if you're starting such a converter/compiler,
> keep in mind the following
> code in TI-BASIC :) (for the sake of the example, I
> haven't optimized this).
>
> :Menu("START",S,"LOAD",L,"QUIT",Q)
> :Lbl S
> :prgmSTARTME
> :Stop
> :Lbl L
> :prgmLOADVARS
> :13/->/L1(Y)
> :L1(X)/->/A[23,4]
> :ClrHome
> :ClrDraw
> :Disp "LOADED"
> :Lbl Q
>
> That's it. Have fun with that.
>
> Yours sincerely,
> Frank Schoep
>
>
>
> ----- Original Message -----
> From: "Patrick Davidson" <pad@OCF.Berkeley.EDU>
> To: <assembly-83@lists.ticalc.org>
> Sent: Thursday, August 16, 2001 7:21 PM
> Subject: [A83] Re: Compiled BASIC ?
>
>
> >
> > On Thu, 16 Aug 2001, TypeR unknown wrote:
> >
> > > I was just wondering, since the TI-OS converts
> every BASIC program to
> > > assembly in real-time, isn't it then possible to
> "pre-compile" a BASIC
> > > program to assembly and then sending that to the
> calc?
> > >
> > > This would mean that you can get the speed of a
> ASM program with the
> > > simplicity of a BASIC program, right?
> > >
> > > It probably sounds too good to be true or else
> it would already have
> > > happened, but I'm still wondering =)
> >
> > There actually have been some efforts to
> "pre-compile" basic programs, but
> > none of the programs I have seen that claim to do
> this are even close to
> > being complete (though I may not have looked at
> every one ever released).
> >
> > The first problem with this idea is that the
> calculator does not really
> > convert to assembly in real time at all, but
> rather only "interprets" it
> > in real time; that is, it analyzes each command to
> see what it does and
> > then runs the necessary pre-existing routines to
> perform each part of it.
> > I am sure there are others on this list much more
> qualified to give
> > details of the calculator's interpreter in
> particular, but this is the
> > general idea of an interpreter.
> >
> > Of course, a compiler could be made that does
> these interpretation steps
> > in advance and actually outputs an assembly
> program. No really complex
> > techniques are even needed to do this, though
> unless you're a really
> > skilled programmer you shouldn't expect to finish
> it the same day you
> > start.
> >
> > More importantly, though, basic isn't slower just
> because it is
> > interpreted. Among other things, basic programs
> use floating point
> > numbers, even though they are often not needed,
> which wastes time (even
> > when floating point is needed, the BCD format used
> by TI makes it less
> > efficient thn it could be). They also have
> variables in the VAT which
> > have to be searched for. Of course, a good
> compiler could mostly overcome
> > these problems, but that would take even more time
> to make.
> >
> > Problems would still remain. Simply outputting
> assembly code isn't the
> > same as outputting good assembly code, as you can
> see by looking at some
> > of the C compilers for the calculators which write
> code several times
> > larger than slower than what any decent assembly
> programmer could easily
> > do. The problem would be even worse for TI-basic,
> since basic programs
> > are designed even more differently from assembly
> than a C program is.
> >
> >
> >
>
>
>
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