code guessing, round #41 (completed)

! Copyright (C) 2023 Aleksander Sabak.
! See https://factorcode.org/license.txt for BSD license.
USING: assocs help.markup help.markup.private help.syntax kernel sequences strings urls ;
IN: FALSE

HELP: <FALSE-state>
{ $values
    { "stack" sequence } { "dictionary" assoc }
    { "state" FALSE-state }
}
{ $description "Creates a new FALSE state with clones of " { $snippet "stack" } " and " { $snippet "dictionary" } " as the initial stack and initial variable dictionary respectively." }
{ $see-also <empty-FALSE-state> with-FALSE } ;

HELP: <empty-FALSE-state>
{ $values
    { "state" FALSE-state }
}
{ $description "Creates a new, empty FALSE state. It has no bound variables and an empty stack." }
{ $see-also <FALSE-state> with-FALSE } ;

HELP: FALSE-state
{ $class-description "The class of tuples holding states of FALSE execution to be operated on by compiled FALSE programs. Implements " { $link "sequence-protocol" } " for access to stack and " { $link "assocs-protocol" } " for access to variables." }
{ $see-also <FALSE-state> <empty-FALSE-state> } ;

HELP: FALSE[
{ $syntax "FALSE[ 0 0[ß^$$47>\\58\\>&][48-\\10*+]#%[$1>][$1-]#[\\$0=~][*]#%.]" }
{ $description "Syntax for a FALSE program. It will run on a " { $link FALSE-state } " object. Syntax and semantics of FALSE language are explained in " { $link "FALSE" } "." }
{ $errors "Throws an error when the unsupported " { $snippet "`" } " command is encountered." }
{ $examples
  { $example
    "USING: kernel accessors FALSE prettyprint ;"
    "{ 2 1 3 7 } { } <FALSE-state>
    FALSE[ +-*] call stack>> ."
    "V{ -18 }"
  }
  { $example
    "USING: FALSE prettyprint ;"
    "\"Hello\" FALSE[ \\1+] with-FALSE ."
    "\"Helom\""
  }
}
{ $see-also with-FALSE } ;

HELP: scan-FALSE
{ $values
    { "quote" { $quotation ( state -- state' ) } }
}
{ $description "Reads a FALSE program from parser input until a closing " { $snippet "[" } " and compiles into a quotation to run on a " { $link FALSE-state } "." }
{ $errors "Throws an error when the unsupported " { $snippet "`" } " command is encountered." }
{ $see-also POSTPONE: FALSE[ } ;

HELP: unsupported-FALSE-command
{ $values
    { "command" object }
}
{ $description "Throws an " { $link unsupported-FALSE-command } " error." }
{ $error-description "Thrown during FALSE compilation if the " { $snippet "`" } " command is encountered." } ;

HELP: with-FALSE
{ $values
    { "seq" sequence } { "q" { $quotation ( ..A state -- ..B state' ) } }
    { "seq'" sequence }
}
{ $description "Wrapper around quotations transforming FALSE state. Creates a new " { $link FALSE-state } " instance with " { $snippet "seq" } " as its initial stack, runs " { $snippet "q" } " on it and extracts the final stack into a new sequence of the same type as " { $snippet "seq" } "." }
{ $examples
  { $example
    "USING: FALSE prettyprint ;"
    "{ 2 1 3 7 } FALSE[ +-*] with-FALSE ."
    "{ -18 }"
  }
  { $example
    "USING: FALSE prettyprint ;"
    "\"Hello\" FALSE[ \\1+] with-FALSE ."
    "\"Helom\""
  }
}
{ $see-also <FALSE-state> <empty-FALSE-state> }
;

ARTICLE: "FALSE" "FALSE language"
{ { $url URL"https://esolangs.org/wiki/FALSE" "FALSE" } " is a stack-based esoteric language designed by " { $url URL"https://strlen.com/" "Wouter van Oortmerssen" } " in 1993, with the goal of creating a powerful and obfuscated language with as small a compiler as possible." }

{ $heading "Overview of FALSE" }
FALSE has a simple concatenative syntax where each character is one command, apart from numbers which can span multiple characters. It operates on a stack but it can also store values in 26 variables named { $snippet "a" } through { $snippet "z" } . It works with three types of values:
{ $list
  { "Signed integers, for which literals are strings of digits or " { $snippet "'" } " followed by a character" }
  { "Variable references, for which literals are their names" }
  { "Quotations, for which literals are programs enclosed in " { $snippet "[...]" } }
}
It provides a set of builtin operators:
{ $table 
  { { $snippet "$" } { $snippet ( x -- x x ) } "Duplicates top of the stack" }
  { { $snippet "%" } { $snippet ( x -- ) } "Drop top of the stack" }
  { { $snippet "\\" } { $snippet ( x y -- y x ) } "Swaps top two elements on the stack" }
  { { $snippet "@" } { $snippet ( x y z -- y z x ) } "Pulls the third element from the stack to the top" }
  { { $snippet "ø" } { $snippet ( x n*x n -- x n*x x ) } "Replaces a number from top of the stack with an element that deep into the stack" }
  { { $snippet "O" } { $snippet ( x n*x n -- x n*x x ) } "Nonstandard, same as ø" }
  { { $snippet "+" } { $snippet ( x y -- z ) } "Adds top two numbers on the stack" }
  { { $snippet "-" } { $snippet ( x y -- z ) } "Subtracts top from second on the stack" }
  { { $snippet "*" } { $snippet ( x y -- z ) } "Multiplies top two numbers on the stack" }
  { { $snippet "/" } { $snippet ( x y -- z ) } "Divides second on the stack by top" }
  { { $snippet "_" } { $snippet ( x -- y ) } "Negates top of the stack" }
  { { $snippet "&" } { $snippet ( x y -- z ) } { "Performs a bitwise " { $snippet "and" } " on top two values o the stack" } }
  { { $snippet "|" } { $snippet ( x y -- z ) } { "Performs a bitwise " { $snippet "or" } " on top two values o the stack" } }
  { { $snippet "~" } { $snippet ( x -- y ) } "Performs a bitwise negation on top of the stack" }
  { { $snippet ">" } { $snippet ( x y -- z ) } "Pushes -1 if second on the stack is greater than top, otherwise pushes 0" }
  { { $snippet "=" } { $snippet ( x y -- z ) } "Pushes -1 if top two on the stack are equal, otherwise pushes 0" }
  { { $snippet "!" } { $snippet ( quot -- ) } "Executes top of stack" }
  { { $snippet "?" } { $snippet ( ? quot -- ) } "Executes top of stack if second on stack is non-zero" }
  { { $snippet "#" } { $snippet ( pred body -- ) } { "Executes " { $snippet "pred" } ", pops its return value, and loops calling " { $snippet "body" } ", " { $snippet "pred" } " and popping until the value popped is zero" } }
  { { $snippet ";" } { $snippet ( ref -- x ) } "Fetch from a variable reference" }
  { { $snippet ";" } { $snippet ( x ref -- ) } "Store into a variable reference" }
  { { $snippet "^" } { $snippet ( -- x ) } "Fetch a character from input stream, or -1 if input stream is exhausted" }
  { { $snippet "," } { $snippet ( x -- ) } "Print a character with a given code to the output stream" }
  { { $snippet "." } { $snippet ( x -- ) } "Print a number to the output stream" }
  { { $snippet "ß" } { $snippet ( -- ) } "Flush the input/output stream" }
  { { $snippet "B" } { $snippet ( -- ) } "Nonstandard, same as ß" }
  { { $snippet "`" } { $snippet ( -- * ) } "Unsupported" }
}
It also has two additional syntax constuctions:
{ $list
  { { $snippet "\"...\"" } " - print string enclosed in quotation marks" }
  { { $snippet "{...}" } " - ignore anything in curly braces" }
}

{ $heading "Vocabulary" }
The { $vocab-link "FALSE" } vocabulary provides a FALSE to Factor compiler in two words:
{ $subsections scan-FALSE POSTPONE: FALSE[ }
These offer a way to parse FALSE into quotations that take and return a FALSE state object. State objects can be constructed from a sequence which will form the initial stack and an assoc which will define initial variable bindings. The vocabulary also includes a wrapper word for using a FALSE quotation as a function transforming a sequence:
{ $subsections FALSE-state with-FALSE }

{ $heading "Implementation specific features" }
This FALSE to Factor compiler differs from the standard in several ways:
{ $list
  { "It doesn't support the " { $snippet "`" } " command" }
  { "It supports " { $snippet "O" } " and " { $snippet "B" } " commands as aliases to " { $snippet "ø" } " and " { $snippet "ß" } " respectively" }
  { "Any character not recognised as a FALSE command can be used as a variable reference, and variable references are stored as numbers on the stack which allows any number to be a variable reference as well" }
}

;

ABOUT: "FALSE"

! Copyright (C) 2023 Aleksander Sabak.
! See https://factorcode.org/license.txt for BSD license.
USING: io.streams.string kernel tools.test FALSE FALSE.private ;
IN: FALSE.tests


! scan-FALSE is not tested because testing with a custom lexer
! is too much effort


{ { } } [
    { } [ ] with-FALSE
] unit-test


{ 1 1 } FALSE[ [asd'f{fsd"}"as{fdsaf"[-+*]\]]
must-infer-as


{ "AA" } [
    "A" FALSE[ $] with-FALSE
] unit-test


{ "BA" } [
    "AB" FALSE[ \] with-FALSE
] unit-test


{ "A" } [
    "AB" FALSE[ %] with-FALSE
] unit-test


{ "BCA" } [
    "ABC" FALSE[ @] with-FALSE
] unit-test


{ { 2 1 3 7 2 } } [
    { 2 1 3 7 3 } FALSE[ O] with-FALSE
] unit-test


{ { 2 1 3 7 2 } } [
    { 2 1 3 7 3 } FALSE[ ø] with-FALSE
] unit-test


{ "Hello" } [
    "" FALSE[ 'H'e'l'l'o] with-FALSE
] unit-test


{ { 213 7 } } [
    { } FALSE[ 213 7] with-FALSE
] unit-test


{ { 220 } } [
    { } FALSE[ 213 7+] with-FALSE
] unit-test


{ { 206 } } [
    { } FALSE[ 213 7-] with-FALSE
] unit-test


{ { -2137 } } [
    { } FALSE[ 2137_] with-FALSE
] unit-test


{ { 1491 } } [
    { } FALSE[ 213 7*] with-FALSE
] unit-test


{ { 30 } } [
    { } FALSE[ 213 7/] with-FALSE
] unit-test


{ { 1 } } [
    { } FALSE[ 5 3&] with-FALSE
] unit-test


{ { 7 } } [
    { } FALSE[ 5 3|] with-FALSE
] unit-test


{ { -6 } } [
    { } FALSE[ 5~] with-FALSE
] unit-test


{ { -1 } } [
    { } FALSE[ 5 5=] with-FALSE
] unit-test


{ { 0 } } [
    { } FALSE[ 5 6=] with-FALSE
] unit-test


{ { 0 } } [
    { } FALSE[ 5 6>] with-FALSE
] unit-test


{ { 0 } } [
    { } FALSE[ 5 5>] with-FALSE
] unit-test


{ { -1 } } [
    { } FALSE[ 5 4>] with-FALSE
] unit-test


{ { [ ] } } [
    { } FALSE[ []] with-FALSE
] unit-test


{ { 1 } } [
    { } FALSE[ [1]!] with-FALSE
] unit-test


{ { 1 } } [
    { } FALSE[ 1_[1]?] with-FALSE
] unit-test


{ { } } [
    { } FALSE[ 0[1]?] with-FALSE
] unit-test


{ { } } [
    { } FALSE[ [0][7]#] with-FALSE
] unit-test


{ { 6 } } [
    { } FALSE[ 0 1[][6\]#] with-FALSE
] unit-test


{ { 6 5 4 3 2 1 0 } } [
    { } FALSE[ 7[1-$][$]#] with-FALSE
] unit-test


{ { } } [
    { } FALSE[ {1 2 3}] with-FALSE
] unit-test


{ { [ ] } } [
    { } FALSE[ [{]}]] with-FALSE
] unit-test


{ { } "Hello" } [
    [ { } FALSE[ "Hello"] with-FALSE ] with-string-writer
] unit-test


{ "" } [
    [ FALSE[ "Hello"] ] with-string-writer nip
] unit-test


{ { } "{" } [
    [ { } FALSE[ "{"] with-FALSE ] with-string-writer
] unit-test


{ { } "1" } [
    [ { } FALSE[ {"}"1"] with-FALSE ] with-string-writer
] unit-test


{ { } "]" } [
    [ { } FALSE[ ["]"]!] with-FALSE ] with-string-writer
] unit-test


{ "" "Hello" } [
    [ "olleH" FALSE[ ,,,,,] with-FALSE ] with-string-writer
] unit-test


{ { } "2137" } [
    [ { 2137 } FALSE[ .] with-FALSE ] with-string-writer
] unit-test


{ { 2 1 3 7 } } [
    { 2 1 3 7 } FALSE[ B] with-FALSE
] unit-test


{ { 2 1 3 7 } } [
    { 2 1 3 7 } FALSE[ ß] with-FALSE
] unit-test


{ "Hello" } [
    "Hello" [ "" FALSE[ ^^^^^] with-FALSE ] with-string-reader
] unit-test


{ T{ FALSE-state } } [
    <empty-FALSE-state>
] unit-test


{ T{ FALSE-state } } [
    { } { } <FALSE-state>
] unit-test


{
    T{ FALSE-state
        { stack V{ 97 98 99 } }
        { dictionary H{ { 97 98 } { 99 100 } } }
    }
} [
    "abc" { "ab" "cd" } <FALSE-state>
] unit-test


{ T{ FALSE-state { stack V{ 0 55 } } } } [
    <empty-FALSE-state> FALSE[ 2 1+3\-'7] call
] unit-test


{
    T{ FALSE-state
        { dictionary H{ { 97 3 } { 98 2 } { 99 1 } } }
    }
} [
    { 1 2 3 } { } <FALSE-state> FALSE[ a:b:c:] call
] unit-test


{
    T{ FALSE-state
        { stack V{ 1 2 3 } }
        { dictionary H{ { 97 1 } { 98 2 } { 99 3 } } }
    }
} [
    { } { { CHAR: a 1 } { CHAR: b 2 } { CHAR: c 3 } }
    <FALSE-state> FALSE[ a;b;c;] call
] unit-test


{
    T{ FALSE-state
        { stack V{ 3 2 1 } }
        { dictionary H{ { 97 3 } { 98 2 } { 99 1 } } }
    }
} [
    { 1 2 3 } { } <FALSE-state> FALSE[ a:b:c:a;b;c;] call
] unit-test


{
    T{ FALSE-state
        { stack V{ 16 49 } }
        { dictionary H{ { 97 [ ($) (*) ] } } }
    }
} [
    <empty-FALSE-state> FALSE[ [$*]a:4a;!7a;!] call
] unit-test


{
    { 15 }
    "12345678910111213141516171819202122233524578helloworld"
} [
    [ { } FALSE[ {tests by luatic made for cg41}1 .
    1 1 + .
    4 1 - .
    2 2 * .
    10 2 / .
    6 _ _ .
    4 3 | .
    8 63 & .
    1 _ ~ 9 + .
    10 a : a ; .
    5 $ 1 + + .
    12 42 % .
    42 13 \ % .
    14 42 42 @ . % %
    15 42 42 2O . % %
    42 42 = ["16"]?
    42 41 > ["17"]?
    42 41_ > ["18"]?
    42_ 41 > ["FAIL"]?
    42_ 41_ > ["FAIL"]?
    41_ 42_ > ["19"]?
    ["20"]!
    [["2"]!["1"]!]![[]]%
    0 ["FAIL"]?
    42 ["22"]?
    '2,'3,[$ 1 > [1- $ f;! \ 1- f;! +]?]f:
    33 f;!.'h,"elloworld"] with-FALSE ] with-string-writer
] long-unit-test


{ { 97 -1 } } [
    "a" [ { } FALSE[ ^^] with-FALSE ] with-string-reader
] unit-test

! Copyright (C) 2023 Aleksander Sabak.
! See https://factorcode.org/license.txt for BSD license.
USING: accessors ascii assocs combinators continuations delegate
delegate.protocols hashtables io kernel lexer math math.parser
namespaces quotations sequences unicode vectors ;
IN: FALSE


ERROR: unsupported-FALSE-command command ;


DEFER: scan-FALSE


<PRIVATE


: peek-char ( -- char|f )
  lexer get dup still-parsing?
  [ dup still-parsing-line?
    [ [ column>> ] [ line-text>> ] bi nth ]
    [ drop CHAR: \n ] if ] [ drop f ] if ;

: consume-char ( -- )
  lexer get dup still-parsing-line?
  [ [ 1 + ] change-column drop ] [ next-line ] if ;

: scan-char ( -- char|f ) peek-char dup [ consume-char ] when ;


: (scan-FALSE-number) ( digit -- number )
  CHAR: 0 - [ peek-char dup ascii:digit? ]
  [ consume-char CHAR: 0 - swap 10 * + ] while drop ;


: (;) ( state -- state )
  dup pop over at* [ drop 0 ] unless suffix! ;

: (:) ( state -- state )
  dup [ pop ] [ pop ] bi swap pick set-at ;

: ($) ( state -- state ) dup last suffix! ;

: (%) ( state -- state ) dup pop* ;

: (\) ( state -- state )
  dup [ pop ] [ pop ] bi [ suffix! ] dip suffix! ;

: (@) ( state -- state )
  dup [ pop ] [ pop ] [ pop ] tri
  [ swap [ suffix! ] dip suffix! ] dip suffix! ;

: (O) ( state -- state )
  dup dup [ length ] [ pop ] bi - 2 - swap nth suffix! ;

: (+) ( state -- state ) dup [ pop ] [ pop ] bi + suffix! ;

: (-) ( state -- state ) dup [ pop ] [ pop ] bi swap - suffix! ;

: (*) ( state -- state ) dup [ pop ] [ pop ] bi * suffix! ;

: (/) ( state -- state )
  dup [ pop ] [ pop ] bi swap /i suffix! ;

: (_) ( state -- state ) dup pop neg suffix! ;

: (&) ( state -- state ) dup [ pop ] [ pop ] bi bitand suffix! ;

: (|) ( state -- state ) dup [ pop ] [ pop ] bi bitor suffix! ;

: (~) ( state -- state ) dup pop bitnot suffix! ;

: (=) ( state -- state )
  dup [ pop ] [ pop ] bi = [ -1 ] [ 0 ] if suffix! ;

: (>) ( state -- state )
  dup [ pop ] [ pop ] bi < [ -1 ] [ 0 ] if suffix! ;

: (!) ( state -- state ) dup pop call( state -- state ) ;

: (?) ( state -- state )
  dup [ pop ] [ pop ] bi 0 =
  [ drop ] [ call( state -- state ) ] if ;

: (#) ( state -- state )
  dup [ pop [ call( state -- state ) ] curry ]
  [ pop [ call( state -- state ) dup pop 0 = ] curry ] bi
  swap until ;

: (^) ( state -- state ) read1 -1 or suffix! ;

: (,) ( state -- state ) dup pop write1 ;

: (.) ( state -- state ) dup pop number>string write ;

ALIAS: (B) flush


CONSTANT: FALSE-dictionary
  H{
    { CHAR: ; (;) }
    { CHAR: : (:) }
    { CHAR: $ ($) }
    { CHAR: % (%) }
    { CHAR: \ (\) }
    { CHAR: @ (@) }
    { CHAR: O (O) }
    { CHAR: ø (O) }
    { CHAR: + (+) }
    { CHAR: - (-) }
    { CHAR: * (*) }
    { CHAR: / (/) }
    { CHAR: _ (_) }
    { CHAR: & (&) }
    { CHAR: | (|) }
    { CHAR: ~ (~) }
    { CHAR: = (=) }
    { CHAR: > (>) }
    { CHAR: ! (!) }
    { CHAR: ? (?) }
    { CHAR: # (#) }
    { CHAR: ^ (^) }
    { CHAR: , (,) }
    { CHAR: . (.) }
    { CHAR: B (B) }
    { CHAR: ß (B) }
  }


CONSTANT: FALSE-sigils
  H{
    { CHAR: {
      [ [ scan-char
          { { CHAR: } [ f ] }
            { f [ \ } throw-unexpected-eof ] }
            [ drop t ] } case ] loop ] }
    { CHAR: "
      [ V{ } clone
        [ scan-char
          { { CHAR: " [ f ] }
            { f [ \ " throw-unexpected-eof ] }
            [ suffix! t ] } case ] loop suffix!
        \ write suffix! ] }
    { CHAR: ' [ scan-char suffix! \ suffix! suffix! ] }
    { CHAR: [ [ scan-FALSE suffix! \ suffix! suffix! ] }
    { CHAR: ` [ CHAR: ` unsupported-FALSE-command ] }
  }


PRIVATE>


! FALSE state

TUPLE: FALSE-state { stack vector } { dictionary hashtable } ;

: <FALSE-state> ( stack dictionary -- state )
  [ V{ } clone-like ] [ H{ } assoc-clone-like ] bi*
  FALSE-state boa ;

CONSULT: assoc-protocol FALSE-state dictionary>> ;

CONSULT: sequence-protocol FALSE-state stack>> ;

M: FALSE-state like drop { } <FALSE-state> ;

M: FALSE-state new-sequence
  state>> new-sequence { } <FALSE-state> ;

M: FALSE-state new-resizable
  state>> new-resizable { } <FALSE-state> ;

M: FALSE-state new-assoc
  dictionary>> new-assoc { } swap <FALSE-state> ;

M: FALSE-state assoc-like
  dictionary>> assoc-like { } swap <FALSE-state> ;

INSTANCE: FALSE-state sequence

INSTANCE: FALSE-state assoc

: <empty-FALSE-state> ( -- state ) { } { } <FALSE-state> ;


: with-FALSE
  ( ..A seq q: ( ..A state -- ..B state' ) -- ..B seq' )
  swap [ H{ } <FALSE-state> swap call stack>> ] keep
  clone-like ; inline


: scan-FALSE ( -- quote )
  V{ } clone
  [ scan-char dup CHAR: ] = ]
  [ { { [ FALSE-dictionary ?at ] [ suffix! ] }
      { [ FALSE-sigils ?at ] [ call( x -- x ) ] }
      { [ dup ascii:digit? ]
        [ (scan-FALSE-number) suffix! \ suffix! suffix! ] }
      { [ dup unicode:blank? ] [ drop ] }
      [ suffix! \ suffix! suffix! ] } cond ] until
  drop >quotation ;


SYNTAX: FALSE[ scan-FALSE suffix! ;

Aleksander Sabak

A FALSE to Factor compiler.

languages
parsing
syntax

                    GNU GENERAL PUBLIC LICENSE
                       Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
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# Paradox: A self-hosted FALSE compiler for Linux x86-64

Paradox is a FALSE compiler emitting 64-bit NASM, written in FALSE itself and targeting the Linux syscall ABI.

Made for [code guessing, round #41](https://cg.esolangs.gay/41/).

Prerequisites: You need NASM and a linker in addition to paradox to compile programs.

You can use an existing FALSE implementation or the included bootstrap.lua to bootstrap paradox.

## Bootstrapping

### Using bootstrap.lua

For any given correct input, bootstrap.lua output is (supposed to be) equal to paradox output.
This means you can use bootstrap.lua as a feature-complete substitue for paradox.

```sh
# compile paradox using bootstrap.lua
./bootstrap.lua < paradox.false > paradox.asm && nasm -f elf64 paradox.asm && ld paradox.o -o paradox
```

### Using an existing FALSE implementation

Note: paradox uses ø and ß rather than O and B in its own source code. It still supports O and B; to bootstrap paradox with a FALSE implementation that does not support these symbols, use `sed -i 's/ø/O/g;s/ß/B/g' paradox.false` to substitute them.

Note: bootstrapping paradox has been tested with several standard compliant FALSE implementations. If it does not work with a certain implementation, it's likely due to a bug in that implementation.

```sh
# make paradox build itself using an existing false implementation to run paradox
existing_run_false paradox.false < paradox.false > paradox.asm && nasm -f elf64 paradox.asm && ld paradox.o -o paradox
```

## Recompiling self

Paradox can (obviously) rebuild itself once it has been bootstrapped, and the result should be equal.

```sh
# rebuild paradox using itself
./paradox < paradox.false > paradox2.asm && nasm -f elf64 paradox2.asm && ld paradox2.o -o paradox2

# verify the resulting binaries are equal
diff paradox paradox2
```

## Additional notes

### run.sh

For convenience and in accordance with the CG spec, paradox includes a `run.sh` script that will automatically compile and execute a file.

```sh
./run.sh my_file.false
```

### Error handling

Due to lack of `stderr` access in FALSE, syntax errors are emitted as `%fatal` NASM-directives, so you will see them at the assembly stage. `bootstrap.lua` uses stderr and a nonzero exit code to signal errors.

### I/O Buffering

Paradox implements buffered I/O. You can use ß or B to flush buffered output.

By default, paradox will use a buffer size of 8192, but this can be changed from the source code by using the "U" postfix on a number literal for example:

```
1024U
```

Sets the buffer size for the program to 1024 **statically, at compile time**. It is not possible to change the buffer size at runtime. If multiple of these statements are found, the one that comes last in the file will determine the buffer size. Note that there may not be a space between the integer literal and the U.

To find out an appropriate buffer size for your system, you can use the following command, if you have a C compiler installed:

```
echo '#include <stdio.h>\nBUFSIZ' | cpp | tail -n1
```

### Adjusting stack size

By default, paradox will use 8MiB for both call stack and data stack each. Changing this works similar to changing the buffer size, except S is used instead of U:

```
16777216S
```

Will set the stack size to 16MiB. This affects both call stack and data stack.

### Inline assembly

Paradox has its own inline assembly syntax: anything between backticks is emitted as assembly, like so:

```
"hi"

{ issue exit(0) syscall }
`mov rax, 60
mov rdi, 0
syscall
`

"bye"
```

The output should be just "hi", without "bye".

### Pointer arithmetic

Paradox (coincidentally) supports pointer arithmetic. Pointers and numbers can be added and subtracted using `+` and `-`.

Note that addition and subtraction (as well as other arithmetic and bitwise operations) operate on 32-bit numbers while pointers are 64-bit, so it will only work reliably as long as the pointers are in the appropriate range.

 `;` can be used to read from a pointer; `:` can be used to write to a pointer. Both operations read/write 64 bits.

To read and write individual bytes, one can use bitwise operations.

Variables and lambdas are pointers.

#### String pointers

`["my_stringy"]$2+;$@11+;+\[$@$@>][1-$;,\]#%%10,` will print my_stringy in reverse (ygnirts_ym). This works with any string. This is due to the binary layout of lambdas containing a single string (consisting of just a call to write with the necessary parameters):

```
0000000000401002 <fun_1>:
  401002:	48 be 00 20 40 00 00 	movabs rsi,0x402000
  401009:	00 00 00
  40100c:	b9 09 00 00 00       	mov    ecx,0x9
  401011:	e8 86 00 00 00       	call   40109c <write>
  401016:	c3                   	ret
```

(generated by `objdump -D -M intel some_binary_here`)

A pointer to the string (0x402000) is stored at offset 2, and the length of the string (0x9) is stored at offset 11.

Strings are stored in the data section, so it is possible to write to them.

It is possible to make memory allocations using strings by compiling your program like so:

```sh
(echo "[\"$(head -c YOUR_ALLOCATION_SIZE /dev/zero)\"]" && cat your_source_file.false) | ./paradox
```

In the program, you can then use `2+;` at the beginning of the file to extract a pointer to your allocation.

Since all operations fetch 64-bits, it is recommended to set the allocation size to 7 bytes higher than desired (if you wish to fetch/write the last few bytes of the allocation individually).

As an example for pointer arithmetic, see `examples/brainfuck.false` which implements brainfuck using paradox pointer arithmetic.

### Building untrue

For maximum FALSE meta, you can use paradox to compile the [untrue](https://github.com/appgurueu/codeguessing/blob/master/41/untrue.false) FALSE interpreter and the resulting binary can be used to run paradox.
Note: Untrue will need an increased stack size to run many programs.

```
# download untrue
curl https://raw.githubusercontent.com/appgurueu/codeguessing/master/41/untrue.false -o untrue.false

# append command to set stack size to 128MiB
echo "134217728S" >> untrue.false

# build untrue
./paradox < untrue.false > untrue.asm && nasm -f elf64 untrue.asm && ld untrue.o -o untrue

# now, we will use untrue to run paradox to compile untrue!

# untrue expects O and B symbols, substitute
sed 's/ø/O/g;s/ß/B/g' paradox.false > paradox_subst.false

# untrue expects program and input to be separated by '<'
(cat paradox_subst.false && echo -n '<' && cat untrue.false) | time ./untrue | tee untrue2.asm

# verify resulting assembly is equal
diff untrue.asm untrue2.asm
```

Using untrue to run paradox to build paradox has also been tested (but takes significantly longer).

#!/usr/bin/env lua

local macros = {
	["$"] = [[
mov rax, [r12]
sub r12, 8
mov [r12], rax
]],
	["%"] = [[
add r12, 8
]],
	["\\"] = [[
mov rax, [r12]
mov rbx, [r12+8]
mov [r12], rbx
mov [r12+8], rax
]],
	["@"] = [[
mov rax, [r12]
mov rbx, [r12+8]
mov rcx, [r12+16]
mov [r12], rcx
mov [r12+8], rax
mov [r12+16], rbx
]],
	["O"] = [[
mov rax, [r12]
lea rax, [r12+8*rax]
mov rax, [rax+8]
mov [r12], rax
]],
	["+"] = [[
mov eax, [r12]
add r12, 8
add [r12], eax
]],
	["-"] = [[
mov eax, [r12]
add r12, 8
sub [r12], eax
]],
	["*"] = [[
mov eax, [r12+8]
imul dword[r12]
add r12, 8
mov [r12], eax
]],
	["/"] = [[
xor edx, edx
mov eax, [r12+8]
idiv dword[r12]
add r12, 8
mov [r12], eax
]],
	["_"] = [[
neg dword[r12]
]],
	["&"] = [[
mov eax, [r12]
and eax, [r12+8]
add r12, 8
mov [r12], eax
]],
	["|"] = [[
mov eax, [r12]
or eax, [r12+8]
add r12, 8
mov [r12], eax
]],
	["~"] = [[
not dword[r12]
]],
	[">"] = [[
mov ebx, 0
mov ecx, -1
add r12, 8
mov eax, [r12]
cmp eax, [r12-8]
cmovg ebx, ecx
mov [r12], ebx
]],
	["="] = [[
mov ebx, 0
mov ecx, -1
add r12, 8
mov eax, [r12]
cmp eax, [r12-8]
cmove ebx, ecx
mov [r12], ebx
]],
	["!"] = [[
add r12, 8
call [r12-8]
]],
	["?"] = [[
call conditional
]],
	["#"] = [[
call loop
]],
	[":"] = [[
add r12, 16
mov rax, [r12-16]
mov rbx, [r12-8]
mov [rax], rbx
]],
	[";"] = [[
mov rax, [r12]
mov rax, [rax]
mov [r12], rax
]],
	[","] = [[
mov rsi, r12
mov rcx, 1
call write
add r12, 8
]],
	["^"] = [[
call read
sub r12, 8
mov [r12], eax
]],
	["."] = [[
call print_num
]],
	["B"] = [[
call flush
]],
}

local fn_counter = 0
local str_counter = 0
local current_int

local line_number = 1
local line_position = 0

local stack_size = 8388608
local buffer_size = 8192

local c

local function read_char()
	local char = io.read(1)

	if char == "\n" then
		line_number = line_number + 1
		line_position = 0
	else
		line_position = line_position + 1
	end

	return char
end

local function syntax_error(msg)
	error("FALSE syntax error at "..line_number..":"..line_position..": " .. msg)
end

local function compile_fn()
	local fn_id = fn_counter
	fn_counter = fn_counter + 1

	print("fun_" .. fn_id .. ":")

	local strings = ""

	c = nil

	while true do
		if not c then
			c = read_char()
		end

		if c and c:match("%d") then
			current_int = current_int or 0
			current_int = current_int * 10 + tonumber(c)
			c = nil
		elseif current_int then
			if c == "S" then
				stack_size = current_int
				c = nil
			elseif c == "U" then
				buffer_size = current_int
				c = nil
			else
				print("sub r12, 8")
				print("mov qword[r12], " .. current_int)
			end
			current_int = nil
		elseif c and c:match("[a-z]") then
			print("sub r12, 8")
			print("mov qword[r12], var_" .. c)
			c = nil
		elseif c == "'" then
			local x = read_char()
			if not x then
				syntax_error("unterminated char literal")
			end
			print("sub r12, 8")
			print("mov qword[r12], " .. x:byte(1))
			c = nil
		elseif c == "\"" then
			local str = {}
			while true do
				local x = read_char()
				if not x then
					syntax_error("unterminated string literal")
				end
				if x == "\"" then
					break
				end
				table.insert(str, x:byte(1))
			end
			print("mov rsi, str_" .. str_counter)
			print("mov rcx, " .. #str)
			print("call write")
			strings = "str_" .. str_counter .. ": db " .. table.concat(str, ",") .. "\n" .. strings
			str_counter = str_counter + 1
			c = nil
		elseif c == "`" then
			while true do
				local x = read_char()
				if not x then
					syntax_error("unterminated inline assembly")
				end
				if x == "`" then
					break
				end
				io.write(x)
			end
			c = nil
		elseif c == "[" then
			local lambda = fn_counter
			print("jmp end_" .. lambda)
			compile_fn()
			if c ~= "]" then
				syntax_error("unterminated lambda")
			end
			print("sub r12, 8")
			print("mov qword[r12], fun_" .. lambda)
			c = nil
		elseif c and c:match("%s") then
			c = nil
		elseif not c or c == "]" then
			break
		elseif c and c:byte(1) == 195 then
			c = read_char()

			if c and c:byte(1) == 184 then
				c = "O"
			elseif c and c:byte(1) == 159 then
				c = "B"
			else
				syntax_error("unknown UTF-8 character")
			end
		elseif c and c:byte(1) == 248 then
			c = "O"
		elseif c and c:byte(1) == 223 then
			c = "B"
		elseif c == "{" then
			while read_char() ~= "}" do end
			c = nil
		elseif c and macros[c] then
			io.write(macros[c])
			c = nil
		else
			syntax_error("unknown character: " .. c)
		end
	end

	print("ret")

	print("section .data")
	io.write(strings)
	print("section .text")

	print("end_" .. fn_id .. ":")
end

print("section .text")

compile_fn()

print("%define STKSIZ " .. stack_size)
print("%define BUFSIZ " .. buffer_size)

io.write([[
section .data
readbuf_len: dq 0
readbuf_cursor: dq 0
writebuf_len: dq 0
section .bss
readbuf: resb BUFSIZ
writebuf: resb BUFSIZ
section .text
read:
mov rax, [readbuf_cursor]
cmp rax, [readbuf_len]
jb .has
mov rax, 0
mov rdi, 0
mov rsi, readbuf
mov rdx, BUFSIZ
syscall
mov [readbuf_len], rax
mov qword[readbuf_cursor], 0
cmp rax, 0
jne .has
mov eax, -1
ret
.has:
mov rax, [readbuf_cursor]
movzx eax, byte[readbuf+rax]
inc qword[readbuf_cursor]
ret
write:
mov rdi, [writebuf_len]
mov rax, BUFSIZ
sub rax, rdi
add rdi, writebuf
mov rdx, rcx
sub rdx, rax
jna .simple
mov rcx, rax
rep movsb
push rsi
push rdx
mov qword[writebuf_len], BUFSIZ
call flush
pop rdx
pop rsi
cmp rdx, BUFSIZ
ja .direct
mov rcx, rdx
mov rdi, writebuf
.simple:
add [writebuf_len], rcx
rep movsb
ret
.direct:
mov rax, 1
mov rdi, 1
syscall
ret
flush:
mov rdx, [writebuf_len]
cmp rdx, 0
je .return
mov rax, 1
mov rdi, 1
mov rsi, writebuf
syscall
mov qword[writebuf_len], 0
.return:
ret
conditional:
add r12, 16
mov eax, [r12-8]
cmp eax, 0
je .return
call [r12-16]
.return:
ret
loop:
add r12, 16
sub rsp, 16
mov rax, [r12-8]
mov [rsp], rax
mov rax, [r12-16]
mov [rsp+8], rax
.loop:
call [rsp]
add r12, 8
mov eax, [r12-8]
cmp eax, 0
je .return
call [rsp+8]
jmp .loop
.return:
add rsp, 16
ret
print_num:
mov rcx, rsp
sub rsp, 16
mov eax, dword[r12]
add r12, 8
mov ebx, eax
neg ebx
cmp eax, 0
cmovl eax, ebx
mov edi, 10
.loop:
dec rcx
xor edx, edx
idiv edi
add dl, '0'
mov byte[rcx], dl
cmp eax, 0
jne .loop
cmp ebx, 0
jle .print
dec rcx
mov byte[rcx], '-'
.print:
mov rsi, rcx
lea rcx, [rsp+16]
sub rcx, rsi
call write
add rsp, 16
ret
global _start
_start:
lea r12, [data_stack+STKSIZ]
lea rsp, [call_stack+STKSIZ]
call fun_0
call flush
mov rax, 60
mov rdi, 0
syscall
section .bss
data_stack: resq STKSIZ
call_stack: resq STKSIZ
]])

print("section .data")
for x = ("a"):byte(1), ("z"):byte(1) do
	print("var_" .. string.char(x) .. ": dq 0")
end