#include <stdio.h>
    #include <stdint.h>
    
    double n0 = 0.5;
    double n1 = -0.5;
    
    //special number, should round to zero
    double n2 = 0.49999999999999994;
    double n3 = -0.49999999999999994;
    
    int32_t round_naive( double n ) {
    
      return n + 0.5;
    }
    
    int32_t round_less_naive( double n ) {
    
      return n > 0.0 ? n + 0.5 : n - 0.5;
    }
    
    int32_t round_my_try( double n ){
    
      int32_t n2 = (int32_t)( n * 2.0 ); // double it
      int bit = n2 & 0x1; // extract the half-bit
      bit = n2 >> 31 ? -bit : bit; // check sign
      return  n2/2 + bit; // adjust
    }
    
    void test( double n ) {
    
      printf( "round_naive      ( %.17f ) -> %d\n", n, round_naive( n ) );
      printf( "round_less_naive ( %.17f ) -> %d\n", n, round_less_naive( n ) );
      printf( "round_my_try     ( %.17f ) -> %d\n\n", n, round_my_try( n ) );
    }
    
    int main(void) {
    
      test( n0 );
      test( n1 );
      test( n2 );
      test( n3 );
    
      return 0;
    }