A C networking SDK for LAN peer-to-peer communication between modern POSIX systems and Classic Macintosh computers.

• 29-function C89 API with a single public header (peertalk.h)
• 3 platform backends: POSIX (BSD sockets), MacTCP (68k/PPC), Open Transport (PPC)
• Zero allocation after init — all buffers pre-allocated in a single block
• Automatic peer discovery via UDP broadcast with instant leave notification
• Reliable (TCP) and fast (UDP) message transports
• ~4,700 lines of SDK code across all platforms

#include "peertalk.h"

PT_Context *ctx;
PT_Init(&ctx, "MyApp");

PT_OnPeerDiscovered(ctx, on_discovered, NULL);
PT_OnConnected(ctx, on_connected, NULL);
PT_OnMessage(ctx, MSG_CHAT, on_chat, NULL);

PT_RegisterMessage(ctx, MSG_CHAT, PT_RELIABLE);
PT_StartDiscovery(ctx);

while (running) {
    PT_Poll(ctx);
}

PT_Shutdown(ctx);

See API Contract for the full 29-function reference.

• Retro68 fork for Classic Mac cross-compilation ($RETRO68_TOOLCHAIN)
• clog — fetched automatically via FetchContent, or pass -DCLOG_DIR=path for a local checkout

# POSIX
mkdir -p build && cd build && cmake .. && make

# 68k MacTCP (Retro68 cross-compiler)
mkdir -p build-68k && cd build-68k
cmake .. -DCMAKE_TOOLCHAIN_FILE=$RETRO68_TOOLCHAIN/m68k-apple-macos/cmake/retro68.toolchain.cmake \
  -DPT_PLATFORM=MACTCP && make

# PPC Open Transport (Retro68 cross-compiler)
mkdir -p build-ppc-ot && cd build-ppc-ot
cmake .. -DCMAKE_TOOLCHAIN_FILE=$RETRO68_TOOLCHAIN/powerpc-apple-macos/cmake/retroppc.toolchain.cmake \
  -DPT_PLATFORM=OT && make

# Option 1: FetchContent (automatic download of peertalk + clog)
include(FetchContent)
FetchContent_Declare(clog
    GIT_REPOSITORY https://github.com/matthewdeaves/clog.git
    GIT_TAG        main
    GIT_SHALLOW    TRUE
)
set(CLOG_BUILD_TESTS OFF CACHE BOOL "" FORCE)
FetchContent_MakeAvailable(clog)

FetchContent_Declare(peertalk
    GIT_REPOSITORY https://github.com/matthewdeaves/peertalk.git
    GIT_TAG        main
    GIT_SHALLOW    TRUE
)
set(PEERTALK_BUILD_TESTS OFF CACHE BOOL "" FORCE)
FetchContent_MakeAvailable(peertalk)
target_link_libraries(myapp PRIVATE peertalk clog)

# Option 2: Local checkout
set(PEERTALK_BUILD_TESTS OFF)
add_subdirectory(${PEERTALK_DIR} ${CMAKE_BINARY_DIR}/peertalk)
target_link_libraries(myapp PRIVATE peertalk)

include/peertalk.h          # Single public header (C89, 29 functions)
src/core/                   # Platform-independent core
src/platform/posix/         # BSD sockets + select()
src/platform/mactcp/        # MacTCP async parameter blocks
src/platform/opentransport/ # OT endpoints + notifiers
tests/                      # 7 test apps

Deploy and run test binaries on real Classic Mac hardware using the classic-mac-hardware-mcp MCP server. See its README for setup.

All test apps verified on real Classic Mac hardware:

• Mac SE (68000, System 6.0.8, MacTCP): test_lifecycle, test_reliable, test_multi PASS
• Performa 6200 (PPC 603, System 7.5.3, MacTCP): test_lifecycle, test_reliable, test_multi, test_init_only PASS
• Performa 6400 (PPC 603e, System 7.6.1, Open Transport): test_lifecycle, test_reliable, test_multi, test_init_only PASS

4-peer multi-peer test verified: all 4 machines (POSIX + Mac SE + 6200 + 6400) discovering, connecting, and exchanging broadcasts simultaneously.

1. Every feature serves Bomberman, Chess, or Chat
2. Pre-allocate everything at init, zero malloc after
3. Poll-based I/O on all platforms (no threads)
4. C89 for maximum portability
5. Measure on real hardware, document honestly

• Architecture Diagrams — C4 Mermaid diagrams (Context, Container, Component, Deployment)
• API Contract
• Specification
• Research Decisions

Retro68 (cross-compilation) + clog (auto-fetched) -> peertalk -> csend, BomberTalk