# emulator

A simple emulator built in C++17 using SDL2 for video/audio. It loads a ROM
file from disk, maps it into memory, and runs a fetch/decode/execute loop
rendered to an SDL window.

## Prerequisites

- **C++17 compiler** — MSVC (Visual Studio 2019 or 2022 Build Tools) on
  Windows. The project is currently configured for the MSVC toolchain.
- **CMake** 3.21 or newer (required for the CMake Presets feature).
- **Ninja** — used as the build generator.
- **vcpkg** — dependencies are declared in `vcpkg.json` (manifest mode), so
  vcpkg fetches them automatically on first configure. A working vcpkg
  installation must be available on the system.
- **Git** — for cloning and for vcpkg to fetch package sources.

## Project layout

```
.
├── CMakeLists.txt        # build definition
├── CMakePresets.json     # configure/build presets (vcpkg + MSVC + Ninja)
├── vcpkg.json            # dependency manifest (sdl2, sdl2-image)
├── .vscode/              # editor / IntelliSense config
├── src/
│   ├── main.cpp          # entry point: parses argv, runs the emulator
│   ├── emulator.hpp      # Emulator class declaration
│   └── emulator.cpp      # Emulator class implementation
└── build/                # generated after configure (gitignored)
```

## Installation

1. **Clone the repository**

   ```sh
   git clone <repo-url> emulator
   cd emulator
   ```

2. **Ensure vcpkg is installed**

   If you do not already have vcpkg, clone and bootstrap it:

   ```sh
   git clone https://github.com/microsoft/vcpkg.git
   cd vcpkg
   .\bootstrap-vcpkg.bat
   ```

   Note its root path — you will reference it in the next step.

3. **Point CMake at the vcpkg toolchain**

   `CMakePresets.json` sets `CMAKE_TOOLCHAIN_FILE` to:

   ```
   C:/Program Files (x86)/Microsoft Visual Studio/18/BuildTools/VC/vcpkg/scripts/buildsystems/vcpkg.cmake
   ```

   If your vcpkg lives elsewhere, edit the `default` configure preset
   (or create a `CMakeUserPresets.json` next to `CMakePresets.json`) so the
   `CMAKE_TOOLCHAIN_FILE` value matches your vcpkg install.

## Setup & build

Configure and build with the bundled preset (uses vcpkg manifest mode, so
`sdl2` and `sdl2-image` are installed automatically on first configure):

```sh
cmake --preset default
cmake --build --preset default
```

The resulting executable is placed in `build/` (e.g. `build/emulator.exe`).

## Running

Pass a ROM file as the only argument:

```sh
.\build\emulator.exe <rom-file>
```

Press **Esc** or close the window to quit.

## Editor / IntelliSense

VS Code IntelliSense is configured in `.vscode/c_cpp_properties.json` to read
`build/compile_commands.json` (generated by the `default` preset). Configure
the project once with `cmake --preset default` so the compile database exists;
IntelliSense will then resolve `SDL.h` and the project headers correctly.