_flint_mpn_tdiv_qr, _flint_mpn_tdiv_qr_newton, _flint_mpn_tdiv_qr_unbalanced, _flint_mpn_tdiv_qr_preinv, _flint_mpn_tdiv_qr_preinvn

The dispatcher behind flint_mpn_tdiv_qr and the individual algorithms for large operands, with its interface; in all of them $r$ may be NULL. The Newton version views $a$ and $b$ as fixed-point numbers and computes $m + 2$ fraction limbs of $a/b$, where $m = \mathit{an} - \mathit{bn} + 1$; since the error is below $4 B^{-2}$ at the integer scale, the integer part is certified whenever the first fraction limb lies in $[2, B-2]$, and the remainder then follows from a low product; otherwise the candidate quotient is corrected by $O(1)$ steps using a full product. The unbalanced version (requires $\mathit{an} > 2\mathit{bn}$ and $\mathit{bn} \ge 3$) divides blockwise, sharing one approximate inverse of $b$ between the $2\mathit{bn} \times \mathit{bn}$ blocks. The preinv version requires $(\mathit{binv}, \mathit{binvn} + 2)$ to be the output of _mp_real_inv_newton(binv, b, bn, binvn) with $\mathit{binvn} \ge m + 2$ and $\mathit{an} \ge m + 2$. The preinvn version uses flint_mpn_preinvn and flint_mpn_divrem_preinvn.