
static uint64_t  add_carry (uint64_t a, uint64_t b, unsigned &carry) 
 Compute a + b and increment carry if there was an overflow.


static uint64_t  add_overflow (uint64_t a, uint64_t b, unsigned &overflow) 
 Compute a + b and set overflow accordingly.


static int64_t  compute_r (const uint64_t *upper, uint64_t *r) 
 Update r = r  (t1 + t2) + (t3 + t2) * b ** 10.


static uint64_t  sub_carry (uint64_t a, uint64_t b, unsigned &carry) 
 Compute a  b and increment carry if there was an overflow.


static uint64_t  sub_overflow (uint64_t a, uint64_t b, unsigned &overflow) 
 Compute a  b and set overflow accordingly.

