#include <sicstus/sicstus.h>

static SP_mutex volatile mutex = SP_MUTEX_INITIALIZER;

int
SP_mutex_lock(SP_mutex *pmx);

static SP_mutex volatile my_mutex = SP_MUTEX_INITIALIZER;
// only access this counter with my_mutex locked
int volatile protected_counter = 0;

// returns the new value of protected_counter
int increment_the_counter(void)
{
  int new_value;

  if(SP_mutex_lock(&my_mutex) == 0) goto error_handling;
  // No other thread can update protected_counter here
  new_value = protected_counter+1;
  protected_counter = new_value;
  if (SP_mutex_unlock(&my_mutex) == 0) goto error_handling;
  return new_value;

error_handling:
  …
}