This example application provides a small abstraction over the runtimes API (files gpio.h and uart.h). Furhtermore, the program in main.cpp implements the demo mentioned in the main README.
For building this demo, a recent clang++ compiler is needed (with support for the wasm32 target), as well as the wasm-ld linker.
After a succesfull installation, the Makefile handles building by the target make all, yielding an out.wasm file.