Question

/*

* bitSum8bit - returns count of number of 1's in a byte

* Examples: bitSum8bit(257) = 2, bitSum8bit(7) = 3

* Legal ops: & ( ) >> +

* Do not use a loop!

*/

int bitSum8bit(int input)

{

  // These are all lines of code that you need.

  int mask = ;

  int quarterSum = ;

  int mask2 = ;

  int halfSum = ;

  int mask3 = ;

  return ;

}

Answer 1

// C program to return count of number of 1's in a byte
#include <stdio.h> 
  
int num_to_bits[16] = {
    0, 1, 1, 2, 1, 2, 2, 3,1, 2, 2, 3, 2, 3, 3, 4
}; 
  
/* Recursively get nibble of a given number  
  and map them in the array  */
unsigned int bitSum8bit(unsigned int input) 
{ 
    int nibble = 0; 
    if (0 == input) 
        return num_to_bits[0]; 
  
    // Find last nibble 
    nibble = input & 0xf; 
  
    // Use pre-stored values to find count 
    // in last nibble plus recursively add 
    // remaining nibbles. 
    return num_to_bits[nibble] + bitSum8bit(input >> 4); 
} 
  
int main() 
{ 
    int input = 257; 
    printf("%d\n", bitSum8bit(input)); 
}