source: doc/papers/concurrency/examples/Fib2.c@ fe065c3

#include <stdio.h>

void mary() {
        printf( "MARY\n" );
}

#define FIB_INIT { 0 }
typedef struct { int next; int fn1, fn2; } Fib;
int fib( Fib * f ) {
        static void * states[] = { &&s1, &&s2, &&s3 };
        goto *states[f->next];
  s1:
        mary();
        f->fn1 = 0;
        f->next = 1;
        return f->fn1;
  s2:
        mary();
        f->fn2 = f->fn1;
        f->fn1 = 1;
        f->next = 2;
        return f->fn1;
  s3:;
        mary();
        int fn = f->fn1 + f->fn2;
        f->fn2 = f->fn1;
        f->fn1 = fn;
        return fn;
}
int main() {
        Fib f1 = FIB_INIT, f2 = FIB_INIT;
        for ( int i = 0; i < 10; i += 1 ) {
                printf( "%d %d\n", fib( &f1 ), fib( &f2 ) );
        }
}

// Local Variables: //
// tab-width: 4 //
// compile-command: "gcc Fib2.c" //
// End: //