#include <iostream>
#include <bitset>
using namespace std;
 
#define ONES (~0ULL)
 
#define MASK(from_bit, nbits) \
  (ONES << (from_bit)) - (ONES << (from_bit) << (nbits))
 
inline unsigned long long mask(unsigned from_bit, unsigned nbits) {
  return (ONES << from_bit) - (ONES << from_bit << nbits);
}
 
int main(int argc, char **argv) {
  cout << "using #define:         " << bitset<64>(MASK(63, 3)) << endl;
  cout << "using inline function: " << bitset<64>(mask(63, 3)) << endl;
  return 0;
}
 

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