⚠️ Clean-Room / Educational

This project is educational and Open Source. No code is copied from other emulators. Implementation based solely on technical documentation and permitted tests.

Start of Phase 2 (v0.0.2)

Date:2025-12-19 StepID:0100 State: Verified

Summary

Phase 2 (v0.0.2) of the Viboy Color project officially begins. This phase focuses on migration from the emulation core to C++/Cython to achieve timing precision necessary for full gameplay, and in the implementation of the Audio subsystem (APU). Cleaning of the workspace was carried out, filing v0.0.1 documentation and removing release artifacts that are not needed in active development.

Hardware Concept

Phase 2 addresses two fundamental challenges of Game Boy emulation:

  1. Timing Accuracy: Original hardware runs at 4.19 MHz with sync Accurate cycle by cycle. The pure Python implementation introduces latency that breaks the logic of Timing-sensitive games. Migration to C++/Cython allows kernel to run at native speed while maintaining the Python interface for frontend and tests.
  2. Audio Processing Unit (APU): The Game Boy includes an audio subsystem with 4 channels: two square wave channels (with sweep and envelope), one arbitrary wave channel (Wave RAM), and one noise channel (LFSR). The APU generates audio at the hardware frequency but it must be sampled and mixed for output at 44100Hz or 48000Hz on the host system.

Hybrid Architecture: Phase 2 implements an architecture where Python handles the orchestration (UI, input, file loading) while C++ handles cycle-by-cycle emulation. Cython acts as a bridge, allowing efficient calls from Python to compiled C++ code.

Implementation

Performed a structural cleanup of the repository to prepare the Phase 2 development environment:

Documentation Archiving v0.0.1

  • Created `docs/archive/` folder: To store closed version documentation.
  • Moved `COMPLETE_REPORT.md`: Filed as `docs/archive/INFORME_v0.0.1_FINAL.md` to preserve the complete history of Phase 1.
  • Initialized `PHASE_REPORT_2.md`: New log document with clear objectives of Phase 2: migration to C++/Cython and APU implementation.

Release Artifact Cleaning

Removed from the development branch (but preserved in the v0.0.1 tag) the following artifacts which are not needed during active development:

  • release/: Compiled binaries from v0.0.1 (Windows, Linux, macOS)
  • installers/: Installation scripts (Inno Setup, Debian, py2app)
  • tools/build_release.py: v0.0.1 build script

Note: The foldersbuild/anddist/they weren't in git (probably in .gitignore), which is correct since they are temporary artifacts of PyInstaller.

Documentation Update

  • README.md: Updated to reflect status "v0.0.2-dev (Work in Progress)" and the Phase 2 roadmap with specific migration tasks to C++/Cython and APU implementation.
  • Binnacle: First entry created (0100) documenting the start of Phase 2.

Design Decisions

Safe Cleaning: All removed artifacts are preserved in the `v0.0.1` tag, so they can be recovered at any time with `git checkout v0.0.1`. This allows maintaining the development branch cleans without losing the work of the previous version.

Phase Separation: The v0.0.1 documentation is archived but accessible, allowing refer to previous technical decisions while developing the new architecture.

Affected Files

  • docs/archive/REPORT_v0.0.1_FINAL.md- Archived documentation from v0.0.1 (moved from root)
  • REPORT_PHASE_2.md- Initialized with Phase 2 objectives and structure
  • README.md- Updated with v0.0.2-dev status and roadmap
  • docs/bitacora/entries/2025-12-19__0100__inicio-phase-2.html- New log entry
  • docs/bitacora/index.html- Updated with new entry (pending)
  • release/- Removed from git (preserved in tag v0.0.1)
  • installers/- Removed from git (preserved in tag v0.0.1)
  • tools/build_release.py- Removed from git (preserved in tag v0.0.1)

Tests and Verification

This entry is administrative in nature and does not require functional testing. However, it was verified:

  • Git: Confirmed that deleted files are preserved in the v0.0.1 tag via git history check.
  • File structure: Checked `docs/archive/` creation and movement correct `COMPLETE_REPORT.md`.
  • Documentation: Verified the update of `README.md` and `INFORME_FASE_2.md` with correct information from Phase 2.

Sources consulted

  • Git Documentation: Tagging and branching strategies
  • Viboy Color Project: `.cursorrules` - Python/C++ Hybrid Architecture Specification
  • Pan Docs: Reference for Future APU Implementation (Phase 2)

Note: This entry is primarily administrative. Technical sources for migration to C++/Cython and APU implementation will be discussed in future posts.

Educational Integrity

What I Understand Now

  • Life Cycle Management: Phase separation using git tags allows Maintain a clean history while preserving previous work. Release artifacts They are not required in active development but should be available in the finalized version.
  • Hybrid Architecture: Migrating to C++/Cython requires careful architecture where Python maintains high level control (UI, events) while C++ handles the critical loop emulation. Cython is the bridge that enables this efficient integration.
  • Environment Preparation: A clean workspace is essential for focus in new development without distractions from artifacts from previous versions.

What remains to be confirmed

  • C++/Cython structure: How to organize `.pyx`, `.pxd`, `.cpp` and `.hpp` files to maintain a clear and scalable architecture.
  • Memory Management: How to handle data transfer between Python and C++ without unnecessary copies, especially for video and audio buffers.
  • Compilation and Build: How to configure `setup.py` to build Cython extensions cross-platform (Windows, Linux, macOS).
  • APU: The specific implementation details of each audio channel and the synchronization with the main emulation loop.

Hypotheses and Assumptions

Performance: I assume that migrating to C++/Cython will solve the timing problems observed in v0.0.1, but this needs to be validated by testing with timing-sensitive games (Tetris, Pokémon) once the migration is complete.

Compatibility: I assume that the hybrid architecture will maintain the portability of the project (Windows, Linux, macOS) using conditional compilation in `setup.py`, but this must be verified on each platform.

Next Steps

  • [ ] Configure Cython build infrastructure (`setup.py`, directory structure)
  • [ ] Create base structure of C++/Cython modules (CPU, MMU, PPU)
  • [ ] Migrate CPU (LR35902) to C++ with Cython wrapper
  • [ ] Migrate MMU to compiled code
  • [ ] Migrate PPU to compiled code
  • [ ] Implement APU (Channel 1: Square Wave with Sweep)
  • [ ] Implement APU (Channel 2: Square Wave)
  • [ ] Implement APU (Channel 3: Wave RAM)
  • [ ] Implement APU (Channel 4: LFSR Noise)
  • [ ] Audio integration with main loop
  • [ ] Validation with timing-sensitive games