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howerj / embed

An embeddable, tiny Forth interpreter with metacompiler.
MIT License
98 stars 19 forks source link

how the image.c is populated from embed.fth initially? #12

Closed brtchip-paul-jiao closed 1 year ago

brtchip-paul-jiao commented 1 year ago

@howerj Thanks for your great work! It is amazing!

I can see the image of VM is stored in the C array embed_default_block of image.c as below: image

when I checked the makefile, I can see this C array is derived from embed.fth by embed.exe -o embed-1.blk embed.fth.

However, the embed.exe above has been loaded into the image. It goes into chick&egg problem. I am wondering how we get the first VM image which can interpret embed.fth?

I am stuck there, can help answer?

howerj commented 1 year ago

This project derived from one of my other projects, https://github.com/howerj/forth-cpu, for that project I wrote a toolchain in C that compiled a Forth like language for that Forth CPU. I then branched off an made the embed project, which then eventually became self hosting, and no longer required the cross-compiler. The embed project was then reintegrated in the Forth CPU project and the toolchain written in C was removed.

When porting to a new CPU/VM now I instead make a cross compiler written for GForth, which is easier to get things self hosting (which I did for the https://github.com/howerj/subleq and https://github.com/howerj/bit-serial Forth projects). The way this system became self-hosting was a lot more convoluted than normal.

The compiler and toolchain is in https://github.com/howerj/forth-cpu/tree/bd6d9daca39b5cac4b779ec37eb6e5939d3dc979 (in the h2.c file, the Forth interpreter in the h2.fth file).

Does this make sense?

brtchip-paul-jiao commented 1 year ago

@howerj Your explanation is good enough. Thanks you very much! Good to close the ticket.