#include <linux/errno.h>
#include <linux/kernel.h>

static long mycounter = 0;

asmlinkage long sys_inccount(void) {
  long newcounter;
  newcounter = mycounter + 1;
  if (newcounter < 0)
    return -EINVAL;
  else
    return mycounter = newcounter;
}

asmlinkage long sys_deccount(void) {
  long newcounter;
  newcounter = mycounter - 1;
  if (newcounter < 0)
    return -EINVAL;
  else
    return mycounter = newcounter;
}

asmlinkage long sys_getcount(void) {
  return mycounter;
}

asmlinkage long sys_zerocount(void) {
  return mycounter = 0;
}