ctarbide / planckforth

Bootstrapping a Forth interpreter from hand-written tiny ELF binary. Just for fun.

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PlanckForth: Bootstrapping an Interpreter from Handwritten 1KB Binary

This project aims to bootstrap a Forth interpreter from hand-written tiny (1KB) ELF binary. This is just for fun. No practical use.

How to build

Only xxd is needed to build PlanckForth.

$ git clone https://github.com/nineties/planckforth.git
$ cd planckforth
$ make
xxd -r -c 8 planck.xxd > planck
chmod +x planck

Implementations in other languages are in others.

Hello World

The hello world program at the beginning looks like this.

$ ./planck
kHtketkltkltkotk tkWtkotkrtkltkdtk!tk:k0-tk0k0-Q

After bootstrapping by bootstrap.fs, it looks like this.

$ ./planck < bootstrap.fs
." Hello World!" cr

bootstrap.fs can also take a file as an input program like this.

$ cat example/fib.fs
: fib dup 2 < unless 1- dup recurse swap 1- recurse + then ;
20 fib . cr
$ ./planck < bootstrap.fs example/fib.fs
6765

Running Tests

$ make test

Builtin Words

code name stack effect semantics
Q quit ( n -- ) Exit the process
C cell ( -- n ) The size of Cells
h &here ( -- a-addr ) The address of 'here' cell
l &latest ( -- a-addr ) The address of 'latest' cell
k key ( -- c ) Read character
t type ( c -- ) Print character
j jump ( -- ) Unconditional branch
J 0jump ( n -- ) Jump if a == 0
f find ( c -- xt ) Get execution token of c
x execute ( xt -- ... ) Run the execution token
@ fetch ( a-addr -- w ) Load value from addr
! store ( w a-addr -- ) Store value to addr
? cfetch ( c-addr -- c ) Load byte from addr with sign extension
$ cstore ( c c-addr -- ) Store byte to addr
d dfetch ( -- a-addr ) Get data stack pointer
D dstore ( a-addr -- ) Set data stack pointer
r rfetch ( -- a-addr ) Get return stack pointer
R rstore ( a-addr -- ) Set return stack pointer
i docol ( -- a-addr ) Get the code pointer of interpreter
e exit ( -- ) Exit current function
L lit ( -- n ) Load immediate
S litstring ( -- c-addr ) Load string literal
+ add ( a b -- c ) c = (a + b)
- sub ( a b -- c ) c = (a - b)
* mul ( a b -- c ) c = (a * b)
/ divmod ( a b -- c d ) c = (a mod b), d = (a / b)
& and ( a b -- c ) c = (a & b)
| or ( a b -- c ) c = (a | b)
^ xor ( a b -- c ) c = (a ^ b)
< less ( a b -- c ) c = (a < b)
u uless ( a b -- c ) c = (a unsigned< b)
= equal ( a b -- c ) c = (a == b)
( shl ( a b -- c ) c = a << b (logical)
) shr ( a b -- c ) c = a >> b (logical)
% sar ( a b -- c ) c = a >> b (arithmetic)
v argv ( -- a-addr u ) argv and argc
V version ( -- c-addr ) Runtime infomation string

Binary Layout

binary layout

Implementations

Implementation of runtime build test status
Handwritten ELF binary for i386-linux make testing i386-linux-handwritten
C make c testing c
Python 3.x make python testing python

Benchmarks

See Wiki/Benchmarks

About

Bootstrapping a Forth interpreter from hand-written tiny ELF binary. Just for fun.

License:MIT License


Languages

Language:Forth 91.2%Language:Python 4.1%Language:C 3.4%Language:Shell 0.8%Language:Makefile 0.3%Language:F# 0.2%