Function pcg128_add

numpy/random/src/pcg64/pcg64.h:123–129

#ifdef PCG_EMULATED_128BIT_MATH

static inline pcg128_t pcg128_add(pcg128_t a, pcg128_t b) {
  pcg128_t result;

  result.low = a.low + b.low;
  result.high = a.high + b.high + (result.low < b.low);
  return result;
}

static inline void _pcg_mult64(uint64_t x, uint64_t y, uint64_t *z1,
                               uint64_t *z0) {