nineties/planckforth

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

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-tQ

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

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

bootstrap.fs can also takes 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

$ ./planck < bootstrap.fs runtests.fs

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 | i386-linux-handwritten | | C | make c | C | | Python 3.x | make python | python |

Benchmarks

See Wiki/Benchmarks

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