yield equivalent in C/JavaScript?

[Robin Becker]

Is there any way to do yielding easily in C? I have a bunch of programs
which are normally connected together using unix pipes. I would like to
merge them and the problem is then how to get them to communicate nicely
using a single process.

the typical process currently looks like

        initialise();
        while((c=getc(stdin))>=0){
                process(c);
                putc(c,stdout);
                }

so if the inputs are reasonable I could just run each to completion
before proceeding with the next by replacing the file streams with
memory ones. That could get messy if the inputs are large.

Is there a neat way to simulate the yield idea? In C I can just about
consider doing some longjump madness, but that wont wash in the other
possible environment which has JavaScript for implementation.
-- 
Robin Becker