Assembler Project

Overview

This project is an assembler for a simplified computer architecture. The assembler takes assembly source files as input, processes them through multiple stages, and generates output files containing machine code, entry labels, and external references.

Project Structure

The project is organized into the following directories and files:

Assembler-C-Labratory/
├── Header_Files/         # Contains header files for modular code structure
├── Images/               # Stores diagrams and relevant images
├── Tests/                # Sample input assembly files
├── LICENSE               # License information
├── Makefile              # Build automation for compiling the assembler
├── README.md             # Documentation of the project
└── Source_Files/         # Core source code of the assembler

Installation

Prerequisites

Ensure you have the following installed:

• GCC compiler (for compiling the C code)
• Make (for build automation)
• A Linux environment (Ubuntu recommended)

Compilation

To build the assembler, run:

make

This will compile all source files and generate an executable assembler.

Usage

Assembler Workflow

   .as file
      |
      v
[ Preprocessor ]   -->  .am file (macros expanded)
      |
      v
[ First Pass ]     -->  Symbol table (labels, addresses)
      |
      v
[ Second Pass ]
      |
      v
[ Output Files ]
├── .ob (machine code)
├── .ent (entry labels)
└── .ext (external references)

Sample Input/Output Flow

Input Files

.as (Original)	.am (Preprocessed)

---

Output Files

.ob (Object Code)	.ent / .ext

Running the Assembler

After compiling, the assembler can be executed with:

./assembler file1 file2 ...

Each input file should be an assembly file (.as extension). The assembler processes the files and generates an intermediate .am file, which is the source file with comments removed, empty lines eliminated, and macros expanded. It then produces the following output files:

• .ob (Object file with machine code)
• .ent (Entry labels file)
• .ext (External labels file)

Example

./assembler example

This will generate example.am, example.ob, example.ent, and example.ext based on the source assembly file.

Source Files

The Source_Files/ directory contains the core implementation of the assembler. The key files are:

Entry Point

• assembler.c: The main entry point of the assembler. It initializes data structures, processes input files, and orchestrates the first and second passes.

Preprocessing

• preprocessor.c: Handles macro expansion and prepares the input for processing.

First and Second Pass

• first_pass.c: Parses the assembly code, identifies labels and errors, and builds the initial symbol table.
• second_pass.c: Resolves label addresses, validates references, and generates the final binary output.

Output Generation

• output_builder.c: Generates .ob, .ent, and .ext output files after successful assembly.

Utility and Error Handling

• utils.c: General utility functions for handling strings, memory, and formatting.
• errors.c: Defines error messages and reporting functions.
• globals.c: Stores global constants and reserved words.
• label_utils.c: Functions for label validation and management.
• command_utils.c: Parses and validates assembly commands.
• vpc_utils.c: Manages memory storage for virtual program execution.

Header Files

The Header_Files/ directory contains corresponding header files defining structures and function prototypes. These headers ensure modularity and maintainability.

Makefile

The Makefile automates the compilation process. Key commands:

• make – Compiles the project.
• make clean – Removes compiled files.

License

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