big_mul_set_vec
r[alen] = big_mul_set_vec(r, a, alen, b[0]);
#define BIG_MUL_SET_VEC(r, a, len, digit) big_mul_set_vec(r, a, len, digit)
extern BIG_CHUNK_TYPE big_mul_set_vec(BIG_CHUNK_TYPE *r, BIG_CHUNK_TYPE *a,
tr[tlen] = big_mul_set_vec(tr, ta + 1, tlen, ta[0]);
r[len] = big_mul_set_vec(r, a, len, a[0]);
r[len] = big_mul_set_vec(r, a, len, a[0]);
r[alen] = big_mul_set_vec(r, a, alen, b[0]);