big_mul_add_vec
big_mul_add_vec(uint32_t *r, uint32_t *a, int len, uint32_t b)
big_mul_add_vec(BIG_CHUNK_TYPE *r, BIG_CHUNK_TYPE *a, int len,
big_mul_add_vec(uint32_t *r, uint32_t *a, int len, uint32_t digit)