multi-(macro)-task is a library for cooperative multitasking using macros.
mmtask is written in pure C language, and it only uses a few simple macros. It should be possible to compile a program using mmtask for every platform or micro-controller.
It is based on the code from this thread, and it is evolving into something similar to the simplest implementation of ASG (Asynchronous State Graphs), by Marc Lobelle, from UCLouvain.