/*
 * saturating-add.c
 */
#include <stdio.h>
#include <assert.h>
#include <limits.h>

int saturating_add(int x, int y) {
  int sum = x + y;
  int sig_mask = INT_MIN;
  /*
   * if x > 0, y > 0 but sum < 0, it's a positive overflow
   * if x < 0, y < 0 but sum >= 0, it's a negetive overflow
   */
  int pos_over = !(x & sig_mask) && !(y & sig_mask) && (sum & sig_mask);
  int neg_over = (x & sig_mask) && (y & sig_mask) && !(sum & sig_mask);

  (pos_over && (sum = INT_MAX) || neg_over && (sum = INT_MIN));

  return sum;
}

int main(int argc, char* argv[]) {
  assert(INT_MAX == saturating_add(INT_MAX, 0x1234));
  assert(INT_MIN == saturating_add(INT_MIN, -0x1234));
  assert(0x11 + 0x22 == saturating_add(0x11, 0x22));
  return 0;
}