mRL78 is a C++20 scaffold for an RL78 emulator. The first milestone targets an RL78/G13-style RL78-S2 CPU core with ELF and Intel HEX loading.

vcpkg is available on this machine at /usr/bin/vcpkg, but CMake still needs a vcpkg root that contains scripts/buildsystems/vcpkg.cmake.

git submodule update --init --recursive
export VCPKG_ROOT=/path/to/vcpkg
cmake --preset llvm_debug
cmake --build --preset llvm_debug
ctest --preset llvm_debug

If you prefer passing the vcpkg toolchain directly:

cmake -S . -B build/llvm_debug \
  -G Ninja \
  -DCMAKE_TOOLCHAIN_FILE=/path/to/vcpkg/scripts/buildsystems/vcpkg.cmake \
  -DVCPKG_TARGET_TRIPLET=x64-linux \
  -DVCPKG_OVERLAY_TRIPLETS=cmake/triplets
cmake --build build/llvm_debug
ctest --test-dir build/llvm_debug --output-on-failure

Observed local tools:

Available presets:

cmake --preset llvm_debug
cmake --build --preset llvm_debug
ctest --preset llvm_debug

The first scaffold tests cover address validation, flat memory bus behavior, CPU reset, unsupported opcode traps, and simple Intel HEX loading.

GitHub Actions runs CI on Git Flow branches and pull requests targeting main or develop. CI checks llvm_debug, asan, and ubsan, initializes submodules, uses vcpkg manifest mode, and verifies compile_commands.json.

Release artifact packaging runs only for version tags such as v0.1.0. It builds llvm_release and uploads a Linux x64 tarball as a workflow artifact.

See docs/ci_cd.md for workflow triggers, release artifact rules, and local equivalents. Because this repository is private, workflow badges are intended for authenticated GitHub viewers.

Real firmware testing is staged because the CPU core does not yet execute the full RL78 instruction set. The project supports loader/trap testing first, then execution tests as instruction coverage grows.

Self-authored RL78/G13 fixtures can be built when rl78-elf-gcc, rl78-elf-objcopy, and rl78-elf-objdump are installed:

cmake --preset llvm_debug -DMRL78_ENABLE_FIRMWARE_FIXTURES=ON
cmake --build --preset llvm_debug --target mrl78_firmware_fixtures
ctest --preset llvm_debug -L firmware

External firmware corpora are supported as local-only inputs:

cmake --preset llvm_debug \
  -DMRL78_ENABLE_EXTERNAL_FIRMWARE_CORPUS=ON \
  -DMRL78_FIRMWARE_CORPUS_DIR=/path/to/rl78/firmware/corpus
ctest --preset llvm_debug -L external_firmware

See docs/testing_real_firmware.md for fixture design, toolchain setup, licensing cautions, and candidate firmware sources.

The project uses namespace-module style instead of subsystem classes:

• behavior lives in free functions inside namespaces;
• state and data live in plain snake_case structs;
• headers do not use using namespace;
• classes are reserved for narrow RAII wrappers or test helpers.

Primary namespaces:

Dependencies are managed by vcpkg manifest mode:

• cli11
• fmt
• gtest

ELFIO is vendored as a Git submodule at external/elfio because it is not available through the active vcpkg registry.

After cloning this repository, initialize submodules with:

git submodule update --init --recursive

Intel HEX parsing is implemented in-tree because the required v1 format support is small and benefits from emulator-specific validation.

Included in v1:

• RL78/G13-oriented RL78-S2 CPU scaffold;
• 20-bit address validation and 1 MiB flat memory;
• CPU reset and unsupported opcode traps;
• ELF and Intel HEX loader APIs;
• CLI commands: run, disasm, and dump_image.

Deferred:

• board models;
• timers and serial I/O;
• peripheral emulation;
• complete interrupt controller behavior;
• complete RL78 instruction execution;
• S3-only instruction behavior.

This project is licensed under GPL-3.0-only. See LICENSE.

• RL78 software manual: https://www.renesas.com/en/document/mah/rl78-family-users-manual-software-rev230
• RL78/G13 hardware manual: https://www.renesas.com/en/document/man/rl78g13-users-manual-hardware
• GNU GPL v3: https://www.gnu.org/licenses/gpl-3.0.en.html
• vcpkg manifest mode: https://learn.microsoft.com/en-us/vcpkg/concepts/manifest-mode
• vcpkg CMake integration: https://learn.microsoft.com/en-us/vcpkg/users/buildsystems/cmake-integration
• LLVM CMake runtime options: https://llvm.org/docs/CMake.html
• Clang toolchain runtime docs: https://clang.llvm.org/docs/Toolchain.html
• GoogleTest CMake quickstart: https://google.github.io/googletest/quickstart-cmake.html
• CMake Presets docs: https://cmake.org/cmake/help/latest/manual/cmake-presets.7.html
• GCC RL78 target options: https://gcc.gnu.org/onlinedocs/gcc/RL78-Options.html
• Hirakuni45 RL78 samples: https://github.com/hirakuni45/RL78
• Renesas IoT reference for RL78: https://github.com/renesas/iot-reference-rl78
• GDB RL78 simulator source: https://sources.debian.org/src/gdb/10.1-2/sim/rl78/rl78.c