Mystery.

Hi,

I understand the following program, not that well but at least i know how it works. But i really can't figure out what it does. Pls give some hints.

Code:

---

#include <stdio.h>

int mystery( unsigned );

int main()
{
  unsigned x;

  printf( "Enter an integer: " );
  scanf( "%u", &x );
  printf( "\nThe result is %d\n", mystery( x ) );
  getch();
  return 0;
}

int mystery( unsigned bits )
{
  unsigned i, mask = 1 << 31, total = 0;

  for ( i = 1; i <= 32; i++, bits <<= 1 )
      if ( ( bits & mask ) == mask )
        ++total;

    return !( total % 2 ) ? 1 : 0;
}

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It counts the occurences of 1's in the binary equývalent of an unsigned integer and returns 1 if the total number of 1's is odd, 0 for even.