Forth in VHDL

[rickman]

On 7/24/2016 11:01 PM, rickman wrote:

On 7/24/2016 10:29 PM, rickman wrote:
I wonder how hard it would be to write a Forth in VHDL? It would likely
be as easy to do in non-synthesizable code as any other language. It
might be a bit harder in synthesizable code. For one, the I/O would
need to be constructed from scratch based on some hardware interface.
The non-synthesizable code could just read from a file... I wonder if
you can read from the console in VHDL? I've never tried that before.

I did a little digging and it looks like you *can* do console I/O in
VHDL using the textio package. So I can't think of anything to stop a
vforth from being written... unless the vforth name has already been used.

I took a look at a C Forth implementation, pForth. I'm not sure I
follow everything he is doing, I guess my C is a bit rusty. I see he
used a large CASE statement for primitive words. I'm not clear on how
the inner interpreter works through the XTs in a word definition for
words compiled into other words. I suppose it is just a matter of
indexes into the dictionary (or pointers in C) but I don't see the code
he is using to manipulate them. He uses a ton of defines which hide the
details and it is a bit of work for me to try to figure this out.

I'll get it sooner or later. I just need to keep reading.

--

Rick C