🐍 Monty Bytecode Interpreter

Welcome to the world of Monty 0.98 — a powerful, stack-based scripting language. This project is a C language interpreter that brings Monty bytecode files to life through a LIFO/FIFO stack implementation. Think of it as Python meets Assembly — but strictly stack.

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📚 Table of Contents

• Overview
• Learning Objectives
• Getting Started
• Monty Bytecode Language
• Implemented Opcodes
• Usage
• Tech Specs
• Contributing
• License

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📌 Overview

This project is a stack and queue interpreter built in C, designed to parse and execute bytecode files written in the Monty language. The interpreter reads Monty .m bytecode files and executes commands using a doubly-linked list to simulate a stack or queue structure.

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🧠 Learning Objectives

By the end of this project, you should understand:

• What LIFO and FIFO mean
• When and why to use a stack vs. a queue
• Common use cases and implementations
• Proper use of global variables
• How to split logic across files using extern
• C compilation flags and Betty code style

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⚙️ Getting Started

1. Clone this repo

   git clone https://github.com/SHEFOO10/monty.git
   cd monty

2. Compile the interpreter

   gcc -Wall -Werror -Wextra -pedantic -std=c89 *.c -o monty

3. Run it

   ./monty bytecodes/filename.m

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🐍 Monty Bytecode Language

Monty is a language that operates on a stack or queue with instructions like:

push 5
push 10
pall

Each line contains one instruction, and files can contain comments (#) and blank lines.

Example output:

10
5

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📜 Implemented Opcodes

Opcode	Description
push	Pushes value onto stack
pall	Prints all stack values
pint	Prints top value
pop	Removes top element
swap	Swaps top two elements
add	Adds top two elements
sub	Subtracts top from second
div	Divides second by top
mul	Multiplies top two elements
mod	Modulus of second by top
nop	Does nothing
pchar	Prints char at top of stack
pstr	Prints string from stack values
rotl	Rotates top to bottom
rotr	Rotates bottom to top
stack	Switches to stack (LIFO) mode
queue	Switches to queue (FIFO) mode

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🖥️ Usage

Running the Interpreter

./monty file.m

Error Handling

Error Type	Message Format
Invalid arguments	USAGE: monty file
File not found	Error: Can't open file <filename>
Invalid opcode	L<line>: unknown instruction <opcode>
Memory fail	Error: malloc failed
Stack errors	E.g. can't pop, can't pint, etc.

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🧪 Tech Specs

• 🐧 Ubuntu 20.04 LTS
• 🧵 Written in ANSI C (C89 standard)
• 🛠️ Style: Betty coding style
• 📂 All prototypes in monty.h
• 🧱 Data structure: doubly-linked list

typedef struct stack_s {
    int n;
    struct stack_s *prev;
    struct stack_s *next;
} stack_t;

typedef struct instruction_s {
    char *opcode;
    void (*f)(stack_t **stack, unsigned int line_number);
} instruction_t;

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👥 Contributing

This was a collaborative effort by two developers as part of a systems programming curriculum. Contributions are welcome for expanding opcode support or optimizing the interpreter.

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📜 License

This project is for educational purposes and is bound by the academic integrity policies of the program it was created under. Plagiarism will result in disqualification.

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💡 Fun Fact

“Monty” is named as a humorous reference to Monty Python — because coding can (and should) be fun.