A furry-themed assembly language and interpreter written in Kotlin.

A furry-themed assembly language and interpreter written in Kotlin.

Inspired by Furcode, the Synacor challenge, and JVM bytecode.

I spent multiple hours on this. Dear god help me...

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Interpreter Guide

This implementation of the FurASM interpreter contains a scripts folder which you can use to test out the language via pre-written FurASM scripts.

Running the interpreter on one or more files
furasm "scripts/HelloWorld.fur" "scripts/Math.fur"

Language Guide

Program Quickstart

1. Create a new file ending with '.fur'
2. Write your script.
3. Run it with the interpreter (view interpreter guide above for more information).

Instructions

Each program contains a set of instructions. These instructions perform different actions.
Instructions can be written like so: <opcode> <arguments>

Example: pet OWO 5 Set the MEW register to 5.

View the opcode listing near the bottom for more information on the different types of instructions.

Comments

Comments are lines that are skipped by the interpreter.
They are useful for documenting your code.

• In an empty line:      ; My comment
• After an instruction: pet MEW 10; My comment

Macros

Macros are instructions that create other instructions, they are used to reduce the amount of lines in a script, while also having the same amount of instructions as a script without said lines.

They always start with @, and can take a type-less value with =.

Example: @print = OwO, What's This? Print "OwO, What's This?" to the console.

To-Be-Implemented

• Labels, label an instruction to give it a pounce-able name (alias for instruction pointers)
• Constants, use string literals as a shortcut for mass-petting (alias for per-character petting)
  • Implemented as macros.
• BEP Meta-Register, the value of it is always the current instruction pointer
• Instruction modification instructions.

Specification

Language

Syntax

• An instruction starts with an opcode, followed by the instruction's arguments.
• A newline signals an instruction's ending.
• Comments come after a semicolon at the end of a line.
• Int literals cannot contain any spaces in them.
• Macros start with a '@', and are followed by their names.
• Macro values (optional) start with '=' and are followed by literally anything.
• Macro names and values are trimmed for whitespace before and after their text values.

Semantics

• A program starts at the first instruction (index 0); however, jumps are 1-indexed.
• All numbers are 32-bit integers. (-2147483647 -> 2147483647)
• Registers can be used as arguments, and if so, their value will be set/gotten.
• Opcodes and register IDs are not case-sensitive.
• The only other valid value are int literals.
• Registers are initialized at 0.
• Macros can contain any value and are processed individually.

Conventions

This serves as the official style guide for FurASM scripts.

• A FurASM file ends with '.fur'
• Opcodes should be in lowercase.
• Register IDs should be in uppercase.
• There should be a single space on each side of the '=' in a macro.

Features

Opcodes

Opcodes are the names of instructions.

0.  pet = Set register to value.
1.  paw = Add a register and a value together.
2.  bop = Subtract a register and a value.
3.  lik = Multiply a register with a value.
4.  kis = Divide a register with a value.
5.  bte = Get the remainder of a register and a value.
6.  cyt = Set register to 0 if value 1 is greater than value 2.
7.  wag = Set register to 0 if value 1 is equal to value 2.
8.  pnc = Jump to instruction and push the pointer of the next instruction to stack.
9.  wig = Jump to instruction.
10. nuz = Pop stack and set current pointer to returned pointer.
11. pat = Skip next instruction if register is 0.
12. yif = Terminate the program.

Macros

Macros are interpreter metadata for condensing multiple, usually tedious, instructions down into one line.

@print - Print a series of characters to the terminal via 'pet MEW'.

Storage

Stack

The stack in an interpreter stores the memory addresses for the next instruction after a 'pnc' instruction so that it may be returned to via 'nuz', this allows for subroutines (low-level functions).

'wig' does not store a memory address as it is used for infinite loops, which may cause a stack overflow.

Registers

0. OWO
1. UWU
2. ONO
3. UNU

Meta-Registers

Meta-registers are registers that do not store a value and instead have a special effect when retrieving/storing a value.

MEW Meta-Register

• When setting the value of this register, it outputs the ASCII representation of the value to the terminal.
• When using this register as an argument, it requests an optional number from the terminal.

DMW (Direct MEW) Meta-Register

• When setting the value of this register, it outputs the value to the terminal.
• When using this register as an argument, it requests a required number from the terminal.