__mul_set
extern double __mul_set(double, double, int *);
dds = __mul_set(dds, __tbl_tens[pm->ndigits],
dds = __mul_set(dds, __tbl_tens[i], &eround);
dds = __mul_set(dds, __tbl_tens[exp], &e);
dds = __mul_set(dds, __tbl_tens[pd->exponent], &e);