1.3 Emscripten SDK

Emscripten is a compiler that compiles C/C++ to WebAssembly (WASM).

Emscripten translates:

• C/C++ code → WebAssembly
• System APIs → JavaScript equivalents
• OpenGL → WebGL

• ☑ WSL2 installed
• ☑ Git available

wsl

# To the opt directory (system-wide)
cd /opt
 
# Clone as root
sudo git clone https://github.com/emscripten-core/emsdk.git
sudo chown -R $USER:$USER /opt/emsdk

Or in home directory (only for your user):

git clone https://github.com/emscripten-core/emsdk.git ~/emsdk
cd ~/emsdk

cd /opt/emsdk   # or ~/emsdk
 
# Install latest stable version
./emsdk install latest
 
# Activate
./emsdk activate latest

Temporary (this session only):

source /opt/emsdk/emsdk_env.sh

Permanent (in .bashrc):

echo 'source /opt/emsdk/emsdk_env.sh' >> ~/.bashrc

# Emscripten Compiler
emcc --version

Expected output:

emcc (Emscripten gcc/clang-like replacement) 3.1.xx

# Additional tools
emar --version
emranlib --version

Create a test file:

cat > hello.c << 'EOF'
#include <stdio.h>
 
int main() {
    printf("Hello from WebAssembly!\n");
    return 0;
}
EOF

Compile to WASM:

emcc hello.c -o hello.js
 
# Run with Node.js
node hello.js
# Output: Hello from WebAssembly!

For the WASM build of OpenSSL, these Emscripten tools are used:

Example:

# Instead of:
./Configure linux-x86_64
make
 
# With Emscripten:
emconfigure ./Configure linux-generic32
emmake make

cd /opt/emsdk   # or ~/emsdk
 
# Fetch updates
git pull
 
# Install latest version
./emsdk install latest
./emsdk activate latest
 
# Reload environment
source ./emsdk_env.sh

Environment not loaded:

source /opt/emsdk/emsdk_env.sh

Emscripten needs Python 3:

# Ubuntu
sudo apt install python3
 
# Fedora
sudo dnf install python3

# Check active version
emcc --version
 
# If outdated, reactivate
cd /opt/emsdk
./emsdk activate latest
source ./emsdk_env.sh

• WASM/Blazor Build
• Back to Preparation

Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional