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Simplified Call/Return Forth

Created: 2022-03-25

Just thinking out loud here about a Forth implementation to try out:

After porting a Forth with traditional indirectly-threaded word definitions (as implemented in JonesFORTH), I’d like to try some alternatives.

Instead of:

4 bytes - link to prev word
1 byte  - length of name + flags
n bytes - (string) name, no 0 termination
address of "interpreter" DOCOL, which executes the rest...
address of word_a
address of word_b
address of word_c
[fetch next instruction and jmp to it]

A Call/Return Forth would instead have the much simpler

4 bytes - link to prev word
1 byte  - length of name
1 byte  - flags
n bytes - (string) name, maybe consider 0 termination to aid in debugging
call word_a
call word_b
call word_c

The idea is that we’re trading the size of the machine instruction for call with the complexity of the indirect threading model. It’s a size vs simplicity and (likely) execution speed tradeoff. I’m really curious how the two would compare in benchmarks for typical tasks.