Warning: Here be dragons...

Toolboxforth is... say what?

A throwback to an 80s style of roll-your-own-even-if-you-shouldn't language design.

This is "toolboxforth". It's a FORTH implementation that has been in my "toolbox" since 2009 (under the name uForth). Back then, I used it primarily on an MSP430. Today it targets the ESP32, Arduino 32 bit (Cortex M) and POSIX compliant operating systems. Backport to MSP430 coming soon!!!

This is a 32 bit FORTH with a 16 bit dictionary. What this means is that the dictionary "op codes" are 16 bit but numbers (RAM, stacks) are 32 bits. Special provision is made for storing 32 bit numbers into the dictionary...

The end result: This makes for a more compacted application that fits on smaller MCUs.

Features

• NEW Now allowed to query/modify fixed point decimal places (default is 5).

• NEW B register. Right now just A<>B to allow two addresses to be accessed. We don't use the stack because we don't really know how big a pointer is (between various MCU/CPUs). So you can store an address in A, access it, swap it with B to allow access to B, and back again.

• NEW The A register. Storing an address (variable or dictionary) into the A register allows access via (c!+) and (c@+) directly (without having to do offsets like in +c! and +c@.

• NEW Consolidated @ and ! access to dictionary and RAM. RAM addresses are now identified by the leftmost bit (of 32 bit word) being set. This way, we can distinguish between RAM and dictionary via using just @ (32 bit value for RAM, 16 bit value for dictionary.

• NEW Coroutines! Just added some preliminary support for coroutines.. Only really took one word "uram!". By assigning differing memory areas (alloted via "allot") we can do tasking!

• ROMable. The dictionary and RAM are separate address spaces (even if dictionary is in RAM).

• Internal data structures/dictionary are FORTH hackable. Use @ ! for all system RAM stuff and dict! dict@ to mess with the dictionary. Dangerous. Expect to crash a lot.

• A good portion is (self) implemented in FORTH. Just enuf C for speed and a minimal FORTH kernel.

• Portable. Just need C. Don't even need a filesystem. MCU dictionaries can be bootraped from POSIX build generated header file.

• 16 and 32 bit MCU friendly. Orignally started life on an MSP430... Tune as you see fit.

• Full interactive console on MCU. Just connect via terminal program at 115200 baud.

• MCU Stub words. Develop MCU targeted apps on desktop and just deploy the image to MCU with minimal dev on MCU.

• FORTH "macros" and compilation via [compile], immediate and postpone. Rewrite the compiler on the fly!

• Tail call recursion!

• Hackable. Everything is hackable. In fact, almost everything is hackable from FORTH itself.

• Inspired by the dozens of FORTHs I've used over the years, but it is it's own thing. Don't expect any standards compliance.

• Ugly. Yeah, this needs not only code refactoring, but conceptual refactoring.

• Stable. Yeah I've shipped stuff using it's prior incarnation as "uforth"

• Constant refactoring: I'm trying to balance making it:

  • Minimal. Never quite as minimal as ColorForth or ArrayForth, but..
  • Fast. Coding essential frequently called words in C
  • Flexible. Defining as much FORTH in FORTH as I can.

Is it for you? Probably not... but if you think so, here it is...

Something to play with or gawk at how wrong it feels..

Details

I'm gonna use the term POSIX below, but you can subsitute Linux, MacOSX, OpenBSD, etc...

Toolboxforth is a FORTH implemented in 1 C source file.

Porting is somewhat easy, but you are going to get your hands dirty. Look at "tbforth-posix.c" for guidance.. (subject to change).

Toolboxforth is hardcoded for a 16 bit word dictionary (max 65535 words -- doesn't sound like a lot, but it has been quite adequate for some major projects). However, toolboxforth uses 32 bit words for the stacks and RAM.

All numbers are stored in RAM as 32 bits. Characters and strings are packed into 32 bit cells, so they have special access words like +c! +c@ and bcopy, where you must provide an "index" (byte count) into the 32 bit words.

This C code is gnarly, but defines just enough FORTH to bootstrap a more usable FORTH. See *.f files for more insight into this opinionated implementation... Some words that could be coded in FORTH are left implemented in C mainly for speed...

Words are compiled into the dictionary as follows: [prevword-cell] [name length & bits] [packed name characters...] [primitive|cells..]

where name length is the lower 6 bits and the upper two bits are reserved, characters are packed 2 bytes per CELL and followed by a list of primitives or cells.

The FORTH code has direct (via indexing) access to the critical RAM and dictionary structures/pointers in the C code via @ and dict@ respectively. Take a look at core.f. You can do some interesting stuff (and a lot crashing) by playing with that.

For example, you should be able to walk the dictionary and mess with it (see the definition for "words" in util.f for a dictionary reading example.

For a more destructive example, the following (from util.f) implements a "forget" that will erase words down to, and including, a "marker".

: mark here (create) [compile] lit , [compile] ; ;
: forget-to-mark ( <marker)  next-word dup (find-head)
    dup if dict@ >r (find-code) exec (here) dict! r> lwa dict! else 2drop  then  ;

Yeah, that's gnarly. No documentation yet, but the best way to explore is to start with core.f and util.f.

As opinionated as this FORTH implementation may be, it has served me well (in actual shippable embeded products!) since 2009.

The "POSIX" (e.g. Linux, OpenBSD, etc) build is really meant to help bootstrap the microcontroller build and to test out apps before dropping down to a microcontroller.

For example: You use the POSIX build to generate a dictionary dump that can be simply included for the microcontroller (currently Arduino ESP32) build.

Look at the Makefile for direction... You currently need Arduino IDE to build the Arduino ESP32 code... and the Makefile (simply, naively) copies the needed files to the subdir.

Right now, only ESP32 is supported..and minimally...more to follow.

You will need libreadline for the POSIX build...

This repo is mainly for my own "backup" and for the morbidly curious... as it is moving/evolving rapidly.

Next Up?

Looking into implementing blocks and a simple line editor...

Who? What?

About Me: I've been a FORTHer since 1984. Yeah, I have never lost my love/need for FORTH. I (still) use it for product development and hobbyist hacking...