fibers

#include <ucontext.h>
#include <malloc.h>
#include <stdio.h>

#define FIBER_STACK 1024*64

ucontext_t uctx_func, uctx_main;

void fiber(){
    printf("Fiber: started\n");
    printf("Fiber: Now swap context to main\n");
    swapcontext(&uctx_func, &uctx_main);
    printf("Fiber: returned\n");
    printf("Fiber: Now swap context to main again\n");
    swapcontext(&uctx_func, &uctx_main);
}

int main(){
    getcontext(&uctx_func);
    uctx_func.uc_link = NULL;
    uctx_func.uc_stack.ss_sp = malloc(FIBER_STACK);
    uctx_func.uc_stack.ss_size = FIBER_STACK;
    uctx_func.uc_stack.ss_flags = 0;
    makecontext(&uctx_func, fiber, 0);

    printf("Main: swap context to fiber\n");
    swapcontext(&uctx_main, &uctx_func);

    printf("Main: returned\n");

    printf("Main: swap context to fiber again\n");
    swapcontext(&uctx_main, &uctx_func);

    printf("Main: returned\n");
    printf("Main: exiting\n");

    return 0;

}