Re: [TUHS] Fwd: struct(1) revived! And a request for help

[arnold@skeeve.com]

Thanks Doug.

Let's hope it can be brought all the way into 64 bit mode.
Dr. Baker has been brought into the loop, so I am hopeful. :-)

Arnold

Douglas McIlroy <douglas.mcilroy@dartmouth.edu> wrote:

> Arnold,
>
> I'm very glad you have revived struct. It is an important historical
> artifact, and it's nice to have it freed from distracting obsolete
> usage.
>
> To my mind, struct ranks among the top accomplishments of our
> department at Bell Labs. It was also a lesson in humility to me.
>
> When Brenda proposed struct, it was obvious that it could be built,
> but I advised against doing so. I thought it would take an endless
> pile of special cases to  generate respectable Ratfor. She demurred,
> saying that she thought she could do better than that. And she was
> right. She produced not only working Ratfor programs, but a
> canonical-form theorem that distinguished those programs from all the
> ad hoc alternatives I had imagined. The value of the theorem was
> attested by users' reports that the derived Ratfort was easier to
> understand than the Fortran they had written themselves.
>
> Doug
>
> ---------- Forwarded message ---------
> From: <arnold@skeeve.com>
> Date: Wed, Jan 12, 2022 at 7:58 AM
> Subject: [TUHS] struct(1) revived! And a request for help
> To: <tuhs@tuhs.org>
>
>
> Hello All.
>
> We recently discussed Brenda Baker's struct program, that read Fortran
> and generated Ratfor.  Many of us remarked as to what a really cool
> program it was and how much we admired it, myself included.
>
> For fun (for some definition of "fun") I decided to try to bring the code
> into the present.  I set up a GitHub repo with the V7, V8 and V10 code,
> and then started work in a separate branch.
>
> (https://github.com/arnoldrobbins/struct, branch "modernize".)
>
> The program has three main parts:
>
> - structure, which reads Fortran and outputs something that is
>   almost Ratfor on standard output.
>
> - beautify, which reads the output of structure and finishes the job,
>   primarily making conditions readable (.not. --> !, removing double
>   negatives, etc.)
>
> - struct.sh - a simple shell script that runs the above two components.
>   This is what the user invokes.
>
> The code was written in 1974. As such, it is rife with "type punning"
> between int, int *, int **, and char *.  These produce a lot of warnings
> from a modern day C compiler.  The code also uses a, er, "unique" bracing
> style, making it nearly illegible to my stuck-in-a-rut programming brain.
>
> Here is what I've accomplished so far:
>
> * Converted every function definition and declaration to use modern (ANSI)
>   C style, adding a header file with function declarations that is
>   included everywhere.
>
> * Run all the code through the indent program, formatting it as traditional
>   K&R bracing style, with tabs.
>
> * Fixed some macros to use modern style for getting parameter values as strings
>   into the macros.
>
> * Fixed a few small bugs here and there.
>
> * Fixed beautify to work with modern byacc/bison (%union) and to work with
>   flex instead of lex. This latter was a challenge.
>
> In structure, only three files still generate warnings, but they all relate
> to integer <--> pointer assignment / use as.  However, when compiled in
> 32 bit mode (gcc -m32), where sizeof(int) is the same as sizeof(pointer),
> despite the warnings, structure works!!
>
> Beautify works, whether compiled in 32 or 64 bit mode.
>
> What I've done so far has been mostly mechanical. I hereby request help from
> anyone who's interested in making progress on "the hard part" --- those three
> files that still generate warnings.
>
> I think the right way to go is to replace int's with a union that holds and
> int, a char* and an int*.  But I have not had the quiet time to dive into
> the code to see if this can be done.
>
> Anyone who has some time to devote to this and is interested, please drop
> me a note off-list.
>
> Thanks,
>
> Arnold Robbins