c65gm/README.md

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# c65gm
A high-level 6502 cross-compiler targeting the ACME Cross-Assembler. c65gm provides a more expressive language for writing 6502 assembly programs, with features like functions, type-checked variables, control flow structures, and compile-time optimizations.
## What It Does
c65gm compiles high-level source code into ACME assembler syntax for the 6502 processor (Commodore 64 and similar platforms). It provides:
- **Type system**: BYTE and WORD variables with scope resolution
- **Functions**: Named functions with parameters and call graph analysis
- **Control flow**: IF/ENDIF, WHILE/WEND, FOR loops, SWITCH/CASE
- **Memory operations**: PEEK/POKE/PEEKW/POKEW with zero-page optimization. Access registers as variables.
- **Operators**: Arithmetic (ADD, SUB), bitwise (AND, OR, XOR)
- **Preprocessor**: File inclusion, macros, conditional compilation, Starlark scripting
- **Standard library**: C64 screen/kernal routines, memory management, string handling, graphics (Koala), FAT16 filesystem, and more (accessed via `#include <file>`, path set by `C65LIBPATH` environment variable)
- **Optimizations**: Constant folding, self-assignment detection
- **Safety features**: Compile-time detection of overlapping absolute addresses in function call chains
## Requirements
- **Go**: Version 1.25.1 or higher (tested with 1.25.5)
- **Acme**: Tested with release 0.97 ("Zem")
The project uses Go modules with these dependencies:
- `github.com/armon/go-radix` - Prefix tree for command lookup
- `go.starlark.net` - Embedded Starlark scripting support
## Building
Build the compiler binary:
```bash
go build -o c65gm
```
Or install to your GOPATH:
```bash
go install
```
## Usage
### Quick Start (Recommended)
Compile and assemble directly to a .prg file:
```bash
./c65gm myprogram.c65 # Creates myprogram.prg
./c65gm -i myprogram.c65 -o game.prg # Creates game.prg
```
### Command Reference
#### Build (compile + assemble to .prg)
```bash
./c65gm build -i myprogram.c65 [-o output.prg] [--keep-asm] [--no-cbm]
./c65gm myprogram.c65 # Default build to myprogram.prg
./c65gm -i myprogram.c65 # Same as above
./c65gm -in myprogram.c65 # Legacy syntax, still works
```
#### Compile (to .asm only)
```bash
./c65gm compile -i myprogram.c65 [-o output.asm]
./c65gm myprogram.c65 -o output.asm # .asm extension triggers compile mode
./c65gm -i myprogram.c65 -out output.asm # Legacy syntax
```
#### Help
```bash
./c65gm help
./c65gm -h
./c65gm --help
```
### Key Features
- **Self-contained**: No external build scripts needed
- **Flexible syntax**: `-i`/`-in` and `-o`/`-out` are equivalent
- **Smart defaults**: Output extension determines mode (.prg = build, .asm = compile)
- **ACME integration**: Automatically finds and runs ACME assembler with `-f cbm` by default
- **Backward compatible**: Legacy `-in`/`-out` flags still work
- **Customizable**: Use `--no-cbm` to disable CBM format, `--keep-asm` to keep intermediate files
## Running Tests
Run all tests:
```bash
go test ./...
```
Run tests with verbose output:
```bash
go test -v ./...
```
Run tests for a specific package:
```bash
go test ./internal/compiler
go test ./internal/commands
```
## Examples
See the `examples/` directory for sample programs:
- `hires/` - High-resolution graphics demo
- `multicolorbm/` - Multicolor bitmap demo
- `memlib_demo/` - Memory library usage
- `switch_demo/` - SWITCH/CASE statement examples
### Building Examples
```bash
cd examples/hires
c65gm hires.c65 # Creates hires.prg
c65gm -i hires.c65 -o demo.prg # Creates demo.prg
c65gm compile -i hires.c65 # Creates hires.asm only
```
The example directories also contain `cm.sh` scripts showing the old build method.
## Documentation
- `language.md` - Complete language reference
- `syntax.md` - Syntax guide
- `commands.md` - Command reference
## Editor Syntaxes
- Kate: copy XML to ~/.local/share/org.kde.syntax-highlighting/syntax/
- Sublime: copy .sublime-syntax to Packages/User/
## License
Copyright (C) 1999, 2025 Mattias Hansson
Distributed under GPL.