-rw-r--r-- 549 saferewrite-20241004/src/int64_ones_num/ref/ones_num.c raw
#include <inttypes.h>

int sum1(unsigned long long x) { return 1 & x; }
int sum2(unsigned long long x) { return sum1(x) + sum1(x >> 1); }
int sum4(unsigned long long x) { return sum2(x) + sum2(x >> 2); }
int sum8(unsigned long long x) { return sum4(x) + sum4(x >> 4); }
int sum16(unsigned long long x) { return sum8(x) + sum8(x >> 8); }
int sum32(unsigned long long x) { return sum16(x) + sum16(x >> 16); }
int sum64(unsigned long long x) { return sum32(x) + sum32(x >> 32); }

int int64_ones_num(int64_t x)
{
  uint64_t y = x;
  return sum64(y);
}