gnupic: pre-announcing Forth for PIC18F chips
Subject:
Re: pre-announcing Forth for PIC18F chips
From:
David McNab ####@####.####
Date:
19 Jan 2005 05:07:30 +0000
Message-Id: <41EDEB06.4010404@rebirthing.co.nz>
####@####.#### wrote:
> Is there any (PIC18) Forth language documents available?
Sorry - the only 'language documents' existing at the moment are the
forth and assembler source files.
I know how rude it is to tell users to RTFS, so I'll write a reasonable
manual before doing the release.
At the moment, code is stable and getting better, and I'm doing some
tidy-ups before writing the doco and demo progs. Looking at first
pre-alpha release in 1-2 weeks.
Cheers
David
>
> Thank you!
>
> - Mengjin -
>
> -----Original Message-----
> From: David McNab ####@####.####
> Sent: Sunday, January 16, 2005 6:04 AM
> To: ####@####.#### ####@####.####
> Subject: pre-announcing Forth for PIC18F chips
>
>
> Hi gnupic and picforth people,
>
> This is a pre-announcement of a coming Forth compiler for the PIC18Fxxx
> chips. I've tentatively called it 'PIC18forth', but am open to
> suggestions for a better name.
>
> PIC18forth is radically different from the PIC16Fxxx-only PicForth
> compiler. Almost nothing in common, since I've written PIC18forth from
> scratch.
>
> Quick summary of features - love them and loathe them:
>
> * signed/unsigned 16-bit data cells and operators
> * software return stack
> * data stack grows up (increasing addresses), while
> return stack grows down (decreasing addresses)
> * total allocated size of data+return stacks can
> be set to anything between 16 and 1024 bytes
> * compiler is written in Python, and is very approachable
> and extensible, even for people new to the code
> * integrated into gputils
> * forth sources get compiled to relocatable assembly (.asm)
> sources, ready for gpasm and gplink
> * the generated code embeds a 16-bit forth vm (token threaded
> execution model) which executes bytecodes
> * the generated code is self-contained, and once assembled
> and linked, can be downloaded/flashed as a standalone program
> * FSR0 is usually used for data stack ptr, FSR1 usually
> used as return stack ptr, FSR2 used as general purpose
> pointer
> * full support for locals (John Hopkins syntax, data
> gets transferred from data stack to a frame on return stack
> * vm design favours code density over execution speed
> * contents of 'code .. end-code' definitions are included
> verbatim in generated assembly source (with '\' comments
> changed to ';')
> * the defining-words 'primitive .. end-primitive' can be
> used in place of 'code .. end-code', to define a word
> in assembler which will be available as a single-byte
> vm instruction - easy to add/remove primitives at will
> * maps to von Neumann memory model, with addresses <8000H
> treated as RAM addresses, and addresses>=8000H treated
> as program ROM addresses
>
> If you're currently hacking with PIC18Fxxx chips, and are interested in
> trying out PIC18forth, please mail me and I'll put you on a list for
> pre-alpha-testers.
>
