Mega65 C Compiler Suite (ca45, cc45)

CONSIDER YOURSELF WARNED: Undergoing heavy development

This project provides a modern, object-oriented development toolchain for the MEGA65 (45GS02) home computer. It consists of two primary tools: cc45 (a C compiler) and ca45 (a 45GS02-optimized assembler).

Project Intent

The goal of this suite is to provide a C-based development environment that leverages the advanced features of the MEGA65, such as its 32-bit registers (Q-mode), 28-bit flat memory addressing, and stack-relative addressing. Unlike traditional 6502 compilers, this toolchain is designed from the ground up to support modern calling conventions and procedural abstractions directly at the assembly level.

Architecture

The compilation process follows a multi-pass pipeline:

1. cc45 (Source to Assembly): Translates C source code into high-level 45GS02 assembly. It performs lexical analysis, builds an Abstract Syntax Tree (AST), and generates assembly code using an optimized procedure system.
2. ca45 (Assembly to Binary): Processes the assembly output, resolves symbols, manages stack offsets for procedures, and emits the final machine code binary.

Design Philosophy

• Procedural Abstraction: Function calls are treated as first-class citizens with named parameters and automated stack cleanup.
• MEGA65 First: Special emphasis is placed on supporting the 45GS02 instruction set enhancements, including a high-level expression engine (EXPR) that handles constant folding and register arithmetic.
• Compatibility: Supports KickAssembler-style syntax (comments, * =, .cpu) for easier porting of existing MEGA65 codebases.
• Inline Assembly: Standard C asm() and __asm__() support for direct hardware control from C source.
• Extensibility: The toolchain uses a visitor-based architecture in C++, making it easy to add new optimizations, language features, or hardware targets.

General Usage

The tools are designed to work together seamlessly. A typical workflow involves compiling a C file directly to a binary:

./bin/cc45 -c -o output.s input.c

This command invokes cc45 to generate output.s, and then automatically calls ca45 to produce output.s.bin.

Testing & Regressions

The suite includes a set of automated tests to verify the compiler and assembler. You can run all tests from the project root:

make test

This script compiles C source files from src/test-resources/ and assembles them to ensure stability and correctness. Outputs are stored in the build/test/ directory.

For detailed information on each tool, refer to:

• doc/cc45.md — Compiler Usage and Features
• doc/ca45.md — Assembler Syntax and Reference