gistfile1.txt

operation(x, y)

a <= x <= b; c <= y <= d


// 32 bit machine

unsigned maxOR(unsigned a, unsigned b,
               unsigned c, unsigned d) {
   unsigned m, temp;

   m = 0x80000000;
   while (m != 0) {
      if (b & d & m) {
         temp = (b - m) | (m - 1);
         if (temp >= a) {b = temp; break;}
         temp = (d - m) | (m - 1);
         if (temp >= c) {d = temp; break;}
      }
      m = m >> 1;
   }
   return b | d;
}

unsigned maxAND(unsigned a, unsigned b,
                unsigned c, unsigned d) {
   unsigned m, temp;

   m = 0x80000000;
   while (m != 0) {
      if (b & ~d & m) {
         temp = (b & ~m) | (m - 1);
         if (temp >= a) {b = temp; break;}
      }
      else if (~b & d & m) {
         temp = (d & ~m) | (m - 1);
         if (temp >= c) {d = temp; break;}
      }
      m = m >> 1;
   }
   return b & d;
}