CHAZZ

CHAZZ

Logo of CHAZZ

CHAZZ is an esoteric programming language or more precisely its interpreter link to repository.

Table of Contents

• Introduction
• Usage
• Horizontally Relative Increment/Decrement
• Manual
  • .FEN explained
    • Structure of FEN
    • Utilized .FEN fields
    • Chess pieces/commands
  • An Example
    • Interpretation
    • Step by Step Explanation
• FAQ
• Outlook/Possible Additions

Introduction

This interpreter was created for the Computermusic and Multimedia class at IEM Graz. The basic guidelines were to implement a Turing complete programming language's interpreter.

Usage

After compiling chazz.c, call the interpreter with any pre-created `.fen` file as follows. Try out the given examples:

<syntaxhighlight lang="bash"> ./chazz ./examples/tutorial.fen </syntaxhighlight>

A flag can be set to display the chess board as HTML:

<syntaxhighlight lang="bash"> ./chazz ./examples/tutorial.fen true </syntaxhighlight>

Horizontally Relative Increment/Decrement

Pawns are interpreted as either increment (P) or decrement (p) of their horizontal position's binary value. A line of pawns on the traditional 8×8 chess board PPPPPPPP is equal to 11111111 and represents 255. Note: binary is interpreted from left to right (2^0 … 2^7).

Manual

Logic of a program is based on placing chess pieces on the chess board represented by a .FEN file. Most recent updates remove the restriction to 8×8 boards.

.FEN explained

FEN (Forsyth-Edwards Notation) is a standard notation for describing a chessboard position. A single line of FEN provides all necessary information to reconstruct a board state.

Structure of FEN

FEN consists of six fields, separated by spaces. CHAZZ does not require FEN to be "valid" in the classical sense.

<syntaxhighlight lang="text"> <Piece Placement> <Active Color> <Castling Rights> <En Passant Target Square> <Halfmove Clock> <Fullmove Number> </syntaxhighlight>

1. Piece Placement: Placement from 8th rank to 1st, `/` separates ranks. Uppercase: white (`K,Q,R,B,N,P`), lowercase: black (`k,q,r,b,n,p`), numbers = empty squares.

  Example: `rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR`

2. Active Color: `w` or `b`. Example: `w`

3. Castling Rights: `KQkq` or `-`. Example: `KQkq`

4. En Passant Target: `e3` or `-`

5. Halfmove Clock: number of halfmoves since last pawn move or capture

6. Fullmove Number: total moves, increments after Black's move

Utilized .FEN fields

• Piece Placement: majority of information for CHAZZ commands
• Active Color: determines which color to interpret first

All other fields are ignored.

Chess pieces/commands

Command	Piece	Description
P	white Pawn	increment binary value relative to current horizontal position
N	white Knight	pointer increment
R	white Rook	write to stdout
B	white Bishop	begin loop
Q	white Queen	push memory value to buffer
K	white King	set 1
p	black Pawn	decrement binary value relative to current horizontal position
n	black Knight	pointer decrement
r	black Rook	read from stdin
b	black Bishop	end loop
q	black Queen	pop buffer content
k	black King	set 0

An Example

Tutorial file: `examples/tutorial.fen`

<syntaxhighlight lang="text"> 4PPQ1/PR6/qPR5/q1PR4/q2PR3/N2PBn2/pRN5/pbKBrRkb w </syntaxhighlight>

Interpretation

• Active Color: `w`
• Piece Placement:

 - `4PP` → ASCII '0', pushed/popped to/from buffer with `Q` and `q`  
 - `PR6`, `qPR5`, `q1PR4`, `q2PR3` → binary values interpreted from pawn horizontal positions  
 - `N` → pointer increment for loop counter  
 - Loop with `B`…`b` executes pointer decrements, pawns, and output with `R`  
 - Input with `r` and output with `R`, loop controlled with `K`/`k`

Step by Step Explanation

Step	Piece(s)	Operation	Memory cell	Content/Action
0.0		initial state	0	0
0.1	4PP	+2^5 +2^6	0	48
0.2	Q	push		buffer: 48
0.3	P	+2^0	0	49
0.4	R	print '1'
0.5	q	pop	0	48
0.6	P	+2^1	0	50
0.7	R	print '2'
…	…	…	…	…

FAQ

• Why doesn't `chazz` output '3' for `PPR5/8/8/8/8/8/8/8 w`?

 - CHAZZ writes ASCII characters to stdout; '3' must be 51.

• Why doesn't `r7/4PPR1/8/8/8/8/8/8 w` accept input?

 - Active color is white, interpreter ignores black pieces until first white piece.

Outlook/Possible Additions

• [ ] Add build/run routines (shell script, Makefile, CMake)
• [x] Add flag to enable/disable graphical output
• [ ] GUI for creating .FEN by drag-and-drop

GitHub Repository