# CMake Installation

This section discusses how to build and install Verilator using cmake. Currently cmake is only officially supported for Windows builds (not Linux).

## Quick Install

1. Install Python for your platform from https://www.python.org/downloads/.

2. Install CMake for your platform from https://cmake.org/download/ or build it from source.

3. If the compiler of your choice is MSVC, then install https://visualstudio.microsoft.com/downloads/. If the compiler of your choice is Clang, then install https://releases.llvm.org/download.html or build it from source.

4. For flex and bison use https://github.com/lexxmark/winflexbison to build and install.

5. For build on Windows using MSVC set environment variable WIN_FLEX_BISON to install directory. For build on Windows/Linux/OS-X using ninja set the environment variable FLEX_INCLUDE to the directory containing FlexLexer.h and ensure that flex/bison is available within the PATH.

To obtain Verilator sources download https://github.com/verilator/verilator/archive/refs/heads/master.zip or clone https://github.com/verilator/verilator using git Obtain Sources.

To build using MSVC:

    cd verilator  # directory containing source files of verilator
    mkdir -p build
    cd build
    cmake .. -DCMAKE_BUILD_TYPE=Release --install-prefix $PWD/../install
    cmake --build . --config Release
    cmake --install . --prefix $PWD/../install

To build using ninja:

    cd verilator
    mkdir -p build
    cd build
    cmake -G Ninja .. -DCMAKE_BUILD_TYPE=Release --install-prefix $PWD/../install -DCMAKE_MAKE_PROGRAM=<path to ninja binary> -DBISON_EXECUTABLE=<path to bison> -DFLEX_EXECUTABLE=<path to flex>
    <path to ninja binary> #execute ninja
    cmake --install . --prefix $PWD/../install

## Usage

To use Verilator set the environment variable `VERILATOR_ROOT` to the install directory specified in the above build.

## Example

    cd verilator/examples
    cd cmake_hello_c
    mkdir -p build
    cd build
    cmake ..  # cmake -G Ninja ..
    cmake --build . --config Release # ninja
    # execute the generated binary