get_next_higher_number_with_same_number_of_ones

#include<stdio.h>
#include<stdint.h>
#include<stdlib.h>

//Ref: http://www.slideshare.net/gkumar007/bits-next-higher-presentation
/*
                   x    CAFE01F0
                  -x    3501FE10
      smallest:x &-x    00000010
    ripple:x+ (x&-x)    CAFE0200
ones:x ^ (x + (x&-x))   000003F0
             ones>>2    000000FC
  ones >> 2/smallest    0000000F
       ripple | ones    CAFE020F
         next higher    CAFE020F
*/

uint32_t get_next_higher_number_with_same_number_of_ones(uint32_t x) {
  printf("%20s  %08X\n", "x", x);
  printf("%20s  %08X\n", "-x", -x);
  uint32_t  smallest = x & -x;
  printf("%20s  %08X\n", "smallest:x &-x", smallest);
  uint32_t  ripple = x + smallest;
  printf("%20s  %08X\n", "ripple:x+ (x&-x)", ripple);
  uint32_t  ones =  x ^ ripple;
  printf("%20s  %08X\n", "ones:x ^ (x + (x&-x))", ones);
  printf("%20s  %08X\n", "ones>>2", ones>>2);
  ones = (ones >> 2)/smallest;
  printf("%20s  %08X\n", "ones >> 2/smallest", ones);
  x = (ripple | ones);
  printf("%20s  %08X\n", "ripple | ones", x);
  return x;
}
int main(void) {
  uint32_t  x = 0xCAFE01F0;
  printf("%20s  %08X\n", "next higher", get_next_higher_number_with_same_number_of_ones(x));
  return 0;
}