source: CIVL/examples/languageFeatures/functionPointer.cvl

/* This program demonstrates the use of function pointer, checking
 * of the equality of $proc and $scope type expressions, and the
 * use of system functions $proc_defined/$scope_defined to check if
 * a $proc/$scope expression is defined.
 * Command line example:
 *     civl verify functionPointer.cvl 
 *     or
 *     civl verify functionPointer.cvl -enablePrintf=false
 *     (if you do not like to see the message printed by those printf function calls.)
 */

#define NPROCS 3

#include <civlc.cvh>
#include <stdio.h>
$proc procs[NPROCS];
$scope scopes[NPROCS];

int min(int a, int b) {
  if (a < b)
    return a;
  else 
    return b;
}

int fDouble(int (*f)(int, int), int a, int b) {
  int result;
  
  result = f(a, b);
  return result * 2;
}

// f is a function pointer type argument
$proc proc_create(void (*f)(int), int x){
  $proc p = $spawn f(x);
  
  return p;
}

void foo(int id) {
  printf("I'm spawned with id %d.\n", id);
  $assert(procs[id] == $self);
  scopes[id] = $here;
  printf("I own scope with id %d.\n", scopes[id]);
}

void main(){
  // min here is a function pointer
  int k = fDouble(min, 5, 8);

  for(int i = 0; i < NPROCS; i++){
    procs[i] = proc_create(foo, i);
  }
  
  for(int i = 0; i < NPROCS; i++){
    $wait(procs[i]);
    printf("Process %d terminates.\n", i);
  }
}