Retro68

A GCC-based cross-compilation environment for 68K Macs. Why? Because there is no decent C++11 Compiler targetting Apple's System 6. If that's not a sufficient reason for you, I'm sure you will find someting more useful elsewhere.

Prerequisites

• Linux or Mac OS X
• CMake 2.8
• boost
• Glasgow Haskell Compiler (GHC)
• Apple Universal Interfaces (tested with version 3.1)
• An ancient Mac and/or an emulator.

The Universal Headers used to be a free download from Apple. However, they have taken the site offline and the license agreement prohibits redistribution, so this might be a bit hard to find nowadays.

Building

Put the C headers from Apple's Universal Interfaces package into a directory called "Universal Headers" at the top level of the tree.

From the top-level Retro68 directory:

cd ..
mkdir Retro68-build
cd Retro68-build
sh ../Retro68/build-toolchain.sh 

The toolchain will be installed in the "toolchain" directory inside the build directory.

Sample programs

Sample programs are built as MacBinary files (.bin) and also automatically wrapped into raw disk images (.dsk). Look under Retro68-build/build-target/ for the compiled binaries.

Overview

Retro68 is an aggegation of various existing free software projects with a few small key components added.

Third Party Components:

• binutils 2.20.1
• gcc 4.7.0 with some Retro68-specific hacks
• newlib 2.10.1 (inside the gcc directory)
• elf2flt (from the ucLinux project's CVS)
• hfsutils 3.2.6 (just for convenience)

Retro68-Specific Components:

• ASFilter
• PrepareHeaders.hs
• MakeAPPL
• libretro
• Sample Program: Raytracer
• Sample Program: App2

binutils

Currently unmodified from the original. Configured for m68k-unknown-elf.

gcc

Various patches and hacks, most importantly:

• Changed register usage.
• Change the way 1-byte and 2-byte parameters are passed.
• added a Microsoft-style 'stdcall' calling convention. What we really want is a 'pascal' calling convention, but that's harder to implement, and the MS one is close enough.

newlib

Standard C library. Currently unmodified. The missing platform-dependent bits haven't been added, instead they are found in 'libretro'.

elf2flt

Converts from ELF to a much simpler binary format. Minor patch: provide symbols around .init and .fini sections

hfsutils:

Included for convenience. No changes.

ASFilter:

The most evil hack. Installs a replacement for m68k-unknown-elf-as that replaces all instructions of the form

jsr __magic_inline_1234_5678_9ABC

by

dc.w 0x1234
dc.w 0x5678
dc.w 0x9abc

PrepareHeaders.hs

A small Haskell program that parses header files (specifically, Apple's Universal Headers), understands inline declarations and translates them to a form that gcc already understands.

For OS Traps (parameters in registers), static inline functions with inline assembly are generated.

For Toolbox Traps (pascal calling convention), the stdcall calling convention and the __magic_inline hack described above are used.

MakeAPPL

Reads a FLAT executable as output by elf2flt and converts it to a MacBinary file containing a classic Macintosh application.

libretro

Contains startup code (handles relocations) and implementations for some standard library functions.

Sample Program: App2

Simple test program, includes an implementation of a simple text console window.

The binary is at Retro68-build/build-target/App2/Test.bin in MacBinary format and also on a disk image named Test.dsk.

Sample Program: Raytracer

Calculates a nice 3D image, pixel by pixel. There are two versions: raytracer.cc is a straightforward almost-plain-C implementation (a few C++ features have been used) using floating point arithmetic.

Raytracer2 makes a bit more use of C++ features; it also uses fixed point arithmetic instead of floating point (operator overloading FTW).

The binaries are in Retro68-build/build-target/Raytracer. Both MacBinary (.bin) and disk image (.dsk) formats are built.

License

The original parts of Retro68 are licensed under GPL3+, as are most other parts. Some parts are licensed GPL2+ or with more liberal licenses. Check the copyright notices in the individual files.