bdiv_qr.c
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上传日期:2022-08-06
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- /* mpn_bdiv_qr -- Hensel division with precomputed inverse, returning quotient
- and remainder.
- Contributed to the GNU project by Torbjorn Granlund.
- THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH MUTABLE INTERFACES. IT IS ONLY
- SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
- GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE.
- Copyright 2006, 2007, 2009 Free Software Foundation, Inc.
- This file is part of the GNU MP Library.
- The GNU MP Library is free software; you can redistribute it and/or modify
- it under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 3 of the License, or (at your
- option) any later version.
- The GNU MP Library is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
- #include "gmp.h"
- #include "gmp-impl.h"
- /* Computes Q = N / D mod B^n,
- R = N - QD. */
- mp_limb_t
- mpn_bdiv_qr (mp_ptr qp, mp_ptr rp,
- mp_srcptr np, mp_size_t nn,
- mp_srcptr dp, mp_size_t dn,
- mp_ptr tp)
- {
- mp_limb_t di;
- mp_limb_t rh;
- if (BELOW_THRESHOLD (dn, DC_BDIV_QR_THRESHOLD) ||
- BELOW_THRESHOLD (nn - dn, DC_BDIV_QR_THRESHOLD))
- {
- MPN_COPY (tp, np, nn);
- binvert_limb (di, dp[0]); di = -di;
- rh = mpn_sbpi1_bdiv_qr (qp, tp, nn, dp, dn, di);
- MPN_COPY (rp, tp + nn - dn, dn);
- }
- else if (BELOW_THRESHOLD (dn, MU_BDIV_QR_THRESHOLD))
- {
- MPN_COPY (tp, np, nn);
- binvert_limb (di, dp[0]); di = -di;
- rh = mpn_dcpi1_bdiv_qr (qp, tp, nn, dp, dn, di);
- MPN_COPY (rp, tp + nn - dn, dn);
- }
- else
- {
- rh = mpn_mu_bdiv_qr (qp, rp, np, nn, dp, dn, tp);
- }
- return rh;
- }
- mp_size_t
- mpn_bdiv_qr_itch (mp_size_t nn, mp_size_t dn)
- {
- if (BELOW_THRESHOLD (dn, MU_BDIV_QR_THRESHOLD))
- return nn;
- else
- return mpn_mu_bdiv_qr_itch (nn, dn);
- }