ULtoxL
extern void ULtoxL ANSI((ULong*, ULong*, Long, int));
ULtoxL(L, B[0]->x, exp[0], rv[0]);
ULtoxL(M, B[1]->x, exp[1], rv[1]);
ULtoxL((ULong*)L, bits, expt, k);
ULtoxL(ULong *L, ULong *bits, Long expt, int k)