Imported from CrownParkComputing/Retro-Copper (AGENTS.md). Install upstream with npx skills add CrownParkComputing/Retro-Copper. Copyright stays with the author.

COPPERLINE — PROJECT KNOWLEDGE BASE

Generated: 2026-03-23 Commit: e018b60e Branch: master

OVERVIEW

Amiga emulator (UAE-based) targeting Linux/macOS/Windows/Android/FreeBSD. C/C++ core (~1.3M lines), CMake build, multi-architecture JIT (ARM64/x86-64). Heterogeneous hardware emulation: M68K + PPC + x86(PCem) + DSP3210 + keyboard MCUs. Copperline emulator backend.

STRUCTURE

amiberry/
├── src/                    # Emulation core (~1100 files)
│   ├── osdep/             # Platform abstraction + GUI + renderers
│   │   ├── imgui/         # Dear ImGui GUI panels (30+ modular)
│   │   └── vkbd/          # Virtual keyboard (touch/GL)
│   ├── include/           # Core headers (145 files — API contracts)
│   ├── jit/               # JIT compiler backends
│   │   ├── arm/           # ARM64 codegen (primary target)
│   │   └── x86/           # x86-64 codegen
│   ├── pcem/              # PCem x86 CPU emulation (vendored, 193 files)
│   ├── archivers/         # Archive formats: 7z, chd, dms, lha, lzx, zip
│   ├── slirp/             # Embedded TCP/IP stack (vendored)
│   ├── ppc/               # PowerPC emulation (PearPC, vendored)
│   ├── qemuvga/           # QEMU VGA board emulation (vendored)
│   ├── softfloat/         # IEEE 754 FP emulation (vendored)
│   ├── dsp3210/           # Motorola DSP emulation
│   ├── kbmcu/             # Keyboard MCU emulation (6500/6805/8039)
│   ├── mame/              # TMS34010 from MAME (vendored)
│   ├── machdep/           # Machine-dependent definitions
│   ├── sounddep/          # Audio backend
│   ├── threaddep/         # Threading abstraction
│   ├── caps/              # IPF disk image support
│   └── cputest/           # CPU validation test suite
├── external/              # Third-party: ImGui, MT-32, FloppyBridge, CAPS, NFD
├── android/               # Kotlin/Compose Android app + Gradle build
├── libretro/              # RetroArch core wrapper + libretro-common
├── cmake/                 # CMake modules, toolchains, platform flags
├── packaging/             # DEB/RPM/DMG/Flatpak/ZIP packaging
├── data/                  # Runtime assets (fonts, icons, floppy sounds, vkbd)
├── controllers/           # SDL game controller mappings
├── whdboot/               # WHDLoad boot files
└── docs/                  # User documentation

WHERE TO LOOK

CONVENTIONS

• Tabs for indentation in C/C++ (no .clang-format — convention-based)
• amiberry_ prefix for platform-specific functions
• UAE naming in emulator core (matches WinUAE upstream)
• ImGui patterns in GUI code
• Platform guards: #ifdef __ANDROID__, #ifdef _WIN32, #ifdef __APPLE__, #ifdef AMIBERRY
• Feature guards: #ifdef USE_OPENGL, #ifdef USE_IMGUI (always defined), #ifdef USE_PCEM, etc.
• Vendored code: pcem/, slirp/, ppc/, qemuvga/, softfloat/, mame/ — minimize modifications

ANTI-PATTERNS (THIS PROJECT)

• NEVER suppress type errors — no as any equivalent hacks
• NEVER modify vendored code in pcem/, slirp/, ppc/, softfloat/ without documenting upstream delta
• NEVER use send_input_event() for new input code — use setjoystickstate()/setjoybuttonstate()
• NEVER assume symlinks work — Windows/Android need std::filesystem::copy()
• NEVER use in-tree builds — CMake enforces out-of-tree
• DO NOT enable #if 0 blocks without understanding context (546 disabled blocks, many intentionally off)
• DO NOT run memset on POSIX zero-fill pages (causes OOM on Android natmem gaps)
• DO NOT modify ROM scanning in parse_cmdline() — must be in early arg loop (before initialize_ini())
• FPU SNAN detection is broken — cannot reliably detect signaling NaN via host FPU
• Filesystem emulation will crash on concurrent host filesystem modifications
• Threading in CHD/osdsync has known data races

UNIQUE STYLES

• Dual entry point: src/main.cpp → src/osdep/main.cpp → amiberry_main() (restart loop)
• Generated code: cpuemu_*.cpp files are generated by gencpu.cpp — do not edit directly
• 64-bit pointer discipline in JIT: PC_P is the ONLY 64-bit virtual register; all others 32-bit M68k values
• Inter-block flag optimization currently disabled (#if 0 in compile_block()) on ARM64
• Android version derived from root CMakeLists.txt project(VERSION) — single source of truth

COMMANDS

# Configure + build (Linux/macOS)
cmake -B build -DCMAKE_BUILD_TYPE=Release && cmake --build build -j$(nproc)

# Windows (MinGW-w64 + vcpkg)
cmake --preset windows-release && cmake --build out/build/windows-release

# Android
cd android && ./gradlew assembleRelease

# Run (no GUI test)
./build/amiberry -G

# Run with logging
./build/amiberry --log

# Cross-compile ARM64
cmake -DCMAKE_TOOLCHAIN_FILE=cmake/Toolchain-aarch64-linux-gnu.cmake -B build

SDL3 KMSDRM STATUS (RPi Console)

As of SDL 3.4.2 (March 2026): KMSDRM has critical open bugs. See docs/sdl3_migration/13_kmsdrm_known_issues.md for full details.

• 🔴 Keyboard input broken (SDL #15166) — TTY grabs all keyboard; SDL app receives nothing. Milestoned SDL 3.6.0.
• 🔴 VT switching broken (SDL #13145) — Ctrl+Alt+Fn non-functional. Milestoned SDL 3.6.0.
• 🟠 RPi 5 requires SDL ≥ 3.4.0 — atomic modesetting restored in PR #11511.
• 🟠 RPi 2/3/Zero not supported — build failures and black screen with SDL3 KMSDRM.
• 🟡 SDL_UNIX_CONSOLE_BUILD=ON disables KMSDRM — never use this CMake flag.
• 🟡 Vulkan + KMSDRM SDL renderer broken — use OpenGL ES (Amiberry already does this).
• ✅ Amiberry KMSDRM handling is correct: forces fullwindow, reuses GUI window, requests GLES 3.0, preserves window on close.
• Minimum viable SDL3 for KMSDRM: SDL ≥ 3.6.0 (unreleased). Until then, recommend users run under a compositor (sway/cage).

NOTES

• No automated tests — manual testing with Amiga software is the methodology
• CLAUDE.md at .claude/CLAUDE.md has comprehensive architecture docs (390 lines) — read it first
• CI builds 15+ platform variants (see .github/workflows/c-cpp.yml)
• macOS user data moved to ~/Documents/Amiberry (startup migration from ~/Library/Application Support/Amiberry)
• WinUAE upstream: Core files (custom.cpp, newcpu.cpp, memory.cpp, etc.) track WinUAE — keep local divergences narrow and merge-friendly
• JIT debugging: Start with src/jit/arm/compemu_support_arm.cpp, src/jit/arm/compemu_arm.h, and src/jit/x86/compemu_support_x86.cpp
• Troubleshooting: Follow a normal edit-build-run-test loop and validate behavior on the target platform

CHILD AGENTS.md

./AGENTS.md (this file)
├── src/AGENTS.md              — Core emulation modules
│   ├── src/include/AGENTS.md  — Header API contracts
│   ├── src/osdep/AGENTS.md    — Platform abstraction + renderers
│   │   └── src/osdep/imgui/AGENTS.md — GUI panels
│   ├── src/jit/AGENTS.md      — JIT compiler architecture
│   └── src/pcem/AGENTS.md     — PCem x86 emulation
├── libretro/AGENTS.md         — RetroArch integration
└── android/AGENTS.md          — Android app architecture