Vmi - A Virtual Machine in C

A simple stack-based virtual machine implemented in C. This project is designed to help you understand how virtual machines work at a low level, including instruction fetching, decoding, and execution.

Features

• Stack-Based Design: Uses a stack for arithmetic and data manipulation.
• Basic Instruction Set: Supports instructions like PSH, POP, ADD, SUB, MUL, DIV, SET, LWD, STO, and HLT.
• File-Based Programs: Reads programs from .asi files (Assembly Instruction).
• Registers: Includes general-purpose registers (A, B, C, D, E, F) and special-purpose registers (IP, SP).
• Memory System: Supports storing and loading values from memory addresses.

Instruction Set

Instruction	Description	Example
PSH <val>	Push a value onto the stack	PSH 10
POP	Pop the top value from the stack	POP
ADD	Add the top two stack values	ADD
SUB	Subtract the top two stack values	SUB
MUL <val>	Multiply the top stack value by <val>	MUL 2
DIV <val>	Divide the top stack value by <val>	DIV 2
SET <reg>, <val>	Set a register to a value	SET A, 10
LWD <reg>	Load value from a register onto the stack	LWD A
STO <addr>	Store the top stack value at memory address <addr>	STO 0
HLT	Halt the program	HLT

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Getting Started

Prerequisites

• A C compiler (e.g., clang, gcc).
• GNU Make (for building the project).

Building the Project

1. Clone the repository:

   git clone https://github.com/iliasreg/vmi.git
   cd vmi

2. Build the project using make:

   make

3. Run the virtual machine:

   ./vm

Writing Programs

Programs are written in .asi files. Each line contains an instruction. Comments start with ;.

Example Program (test.asi)

; Add 5 and 10 and print the result
PSH 5    ; Push 5 to the stack
PSH 10   ; Push 10 to the stack
ADD      ; Pop 5 and 10, push 15
POP      ; Print the result (15)
HLT      ; Stop the program

Running the Program

1. Save the program in a file (e.g., test.asi).
2. Run the VM with the program:

   ./vm test.asi

Expected Output

Popped Value is: 15

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Project Structure

vmi/
├── vscode/            // VS Code configuration files
├── helpers/           // Helper functions and utilities
│   ├── helpers.c      // Implementation of helper functions
│   └── helpers.h      // Header for helper functions
├── readers/           // File reading and lexing
│   ├── file_lexer.c   // Implementation of file lexer
│   └── file_lexer.h   // Header for file lexer
├── src/               // Source code
│   ├── main.c         // Entry point (minimal code)
│   └── vm/            // Virtual machine core logic
│       ├── vm.c       // Implementation of VM instructions
│       └── vm.h       // Header for VM logic
├── .gitignore         // Git ignore file
├── code.asi           // Example assembly program
├── Makefile           // Build system
└── README.md          // Project documentation

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Key Updates

1. Instruction Set: Added STO, LWD, MUL, DIV, and SUB instructions.
2. Example Program: Updated to demonstrate STO and LWD.
3. Project Structure: Added file_lexer.h and file_lexer.c to reflect the file reading system.
4. Future Improvements: Added plans for control flow and debugging tools.

Let me know if you’d like further tweaks or additions! 🚀

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Contributing

Contributions are welcome! If you'd like to contribute:

1. Fork the repository.
2. Create a new branch for your feature: git checkout -b feature/your-feature.
3. Commit your changes: git commit -m "Add your feature".
4. Push to the branch: git push origin feature/your-feature.
5. Submit a pull request.

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License

This project is licensed under the MIT License. See LICENSE for details.

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