Hey Dan,

I guess the bottom line that anyone would consider while
going for a compiler would be the Generated Code Size
and Ram Usage. If both of them are low, I don't think people
would mind Learning a new langauge. That is one of the reasons
for the success of C. (The other is portability.)

If there is one thing which all compiler writers would love
to add to their compiler, Its a good State Analyzing Optimizer.
Not exactly the kind of Peep Hole Optimizer which most compilers
sport. But this is far too Intelligent and *slower*(well, just a bit
slower!).

I'm thinking of writing an Optimizer for PIC Hex Files.
It would take in a hex file, Disassemble it, and then
try various optimizations. It might even go ahead and
remove certain pieces of code like redundant Bank Selection code,
Page selection code etc. I've discovered that JAL0435 adds interrupt
handler code even if you don't use interrupts. It even does a lot of
redundant page selections on a 16f877. I want to go way beyond the
normal Peep hole optimizers. This I got this Idea from Scott Dattalo,
while he was writing a peep hole Optimizer for the PIC Port of SDCC.

I would prefer to target only PIC16f877, since there is a lot of scope
for optimizations on it. Later on, we could go in for other families
like PIC12,17 and 18.

About 6 months back, I had written a few libraries for Loading and saving
HEX files in Euphoria Language. I had done it for my Programmer Project.
Now, this LIB is going to be really handy in any PIC development project.
Literally all of the PIC development activity is based on the Intel Hex
format.

How about starting a thread on Peep Hole Optimization ?

Jeethu Rao



-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Dan Michaels
Sent: Monday, July 02, 2001 9:46 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: Compiler


Jeethu Rao wrote:
>Dan, you can't change my mind. I've become a Software Stack fanatic.
>Software Stack is worth the striving for.
>And I don't think it'll make a PIC analogous to a Basic Stamp
>in performance.Remember BS is interpreted and PIC native code.
>running even a simple a = b assignment will take atleast 20-25 cycles
>on a BS. Thats what makes Java slower than C or C++.
>

Jeethu, I wasn't really trying to change your mind. I really
would like to see a good Forth for the PIC [maybe there already
is one ???]. As I understand it, programmers in India, especially
Bangalore I believe, have a strong reputation, and I would be
interested to know what kind of performance you could milk out
of Forth.

It does have the great advantage of building compact programs,
of course. In the PC world, I would say my Forth programs are
maybe 5X smaller than if done in C [using DOS, not windoze].

However, speaking from a more practical perspective, one probably
could not make much money from a Forth compiler for PIC, if that was
their intent. Forth was popular a few years ago in the microcontroller
world, but today Basic and C appear to be the big bread winners,
so .........
============


>Anyway, your've got a good Idea out there. We can make something
>similar to the BS and we could write a specially optimized interpreter
>for the production release of that particular program. Sort of pseudo
>native code (Just like what VB 5 used to do). By pseudo native code,
>I mean that the whole program would be written as a set of calls to
>the Run Time Library.
>
>A lot faster than BS but just as easy!
>

Well that is basically what Forth does, of course. The whole program
is just stored as a series of addresses of functions, and you drill
down through the levels, passing down your parameters, and eventually
get down to the core functions, which are in native code [if you
have a fast implementation]. From benchmarks I recall seeing years
ago, Forth was typically about 2X or 3X slower than a "compiled" C or
Basic implementation, but I think on the PIC with stacks implemented
in s.w., it would be much worse. This is just my gut feeling.

cheers,
- dan michaels
www.oricomtech.com
========================

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