From themarkitecht at gmail.com  Tue Mar 16 22:40:30 2021
From: themarkitecht at gmail.com (Mark H)
Date: Tue, 16 Mar 2021 17:40:30 -0500
Subject: [jimtcl] paradigm shift to run scripts from ROM (flash)
Message-ID: <CAA4-YzOHMK4SQE1E-0wt3Okn8sGPKbWNxsZdaEx6sCx3S2XM9A@mail.gmail.com>

Keeping y'all posted regarding this earlier thread:

<snip>
TheMarkitecht at gmail.com:
...a comprehensive solution.  Such as: throughout jim.c, replace all char*
function parameters with a new structure instead, such as "Jim_Text", which
carries both the char* and the known length.  That would mean basically a
wholesale paradigm shift from C-style strings to known-length strings.  You
might say Pascal-style strings, but I wouldn't store the length at the
front of the string data like Pascal does.  That makes it too easy to
overlook a piece of code that needed the rework, introducing insidious
bugs.  The new design should pass all existing test suites verbatim.
</snip>

<snip>
patrick at spellingbeewinnars.org:
I have wanted to do something like this too.
</snip>

I actually went through with that.  Had to touch (I'm guessing) 75% of the
lines of code in the Jim core.  It took about 2 weeks.  It actually works,
using a handful of simple scripts.  Didn't attempt the full Jim core test
suite at that point.    Took some measurements instead.  It saved 14% RAM
in my application on the STM32 MCU.  Of course that depends heavily on the
ratio of number of script lines to number of data objects (data working set
size).  Speed is within plus or minus 1% of Jim 0.79 when running on the PC.


There are some side benefits.  For example Jim's token parsing code got
substantially increased readability.  That's mainly done by replacing
numerous occurrences of copy & pasted code with macro calls instead.


If I recall, I reworked the core code, references code, and regex engine,
and stopped after that for measurements.


I tried Slim OOP on it (https://github.com/TheMarkitecht/slim).  That still
runs out of RAM, although it did manage to start that up without throwing
errors, which is quite promising!


Thoughts anybody?   What should we do with that forked codebase?  It's not
posted anywhere but I might if there's interest.


--
TheMarkitecht at gmail.com

"GUI: (noun) - a method of organizing all my console windows."


Slim OOP for Jim Tcl:  https://github.com/TheMarkitecht/slim
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