1 /* mpn_bdiv_qr -- Hensel division with precomputed inverse, returning quotient 2 and remainder. 3 4 Contributed to the GNU project by Torbjorn Granlund. 5 6 THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH MUTABLE INTERFACES. IT IS ONLY 7 SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST 8 GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE. 9 10 Copyright 2006, 2007, 2009 Free Software Foundation, Inc. 11 12 This file is part of the GNU MP Library. 13 14 The GNU MP Library is free software; you can redistribute it and/or modify 15 it under the terms of the GNU Lesser General Public License as published by 16 the Free Software Foundation; either version 3 of the License, or (at your 17 option) any later version. 18 19 The GNU MP Library is distributed in the hope that it will be useful, but 20 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 21 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 22 License for more details. 23 24 You should have received a copy of the GNU Lesser General Public License 25 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 26 27 #include "gmp.h" 28 #include "gmp-impl.h" 29 30 31 /* Computes Q = N / D mod B^n, 32 R = N - QD. */ 33 34 mp_limb_t 35 mpn_bdiv_qr (mp_ptr qp, mp_ptr rp, 36 mp_srcptr np, mp_size_t nn, 37 mp_srcptr dp, mp_size_t dn, 38 mp_ptr tp) 39 { 40 mp_limb_t di; 41 mp_limb_t rh; 42 43 if (BELOW_THRESHOLD (dn, DC_BDIV_QR_THRESHOLD) || 44 BELOW_THRESHOLD (nn - dn, DC_BDIV_QR_THRESHOLD)) 45 { 46 MPN_COPY (tp, np, nn); 47 binvert_limb (di, dp[0]); di = -di; 48 rh = mpn_sbpi1_bdiv_qr (qp, tp, nn, dp, dn, di); 49 MPN_COPY (rp, tp + nn - dn, dn); 50 } 51 else if (BELOW_THRESHOLD (dn, MU_BDIV_QR_THRESHOLD)) 52 { 53 MPN_COPY (tp, np, nn); 54 binvert_limb (di, dp[0]); di = -di; 55 rh = mpn_dcpi1_bdiv_qr (qp, tp, nn, dp, dn, di); 56 MPN_COPY (rp, tp + nn - dn, dn); 57 } 58 else 59 { 60 rh = mpn_mu_bdiv_qr (qp, rp, np, nn, dp, dn, tp); 61 } 62 63 return rh; 64 } 65 66 mp_size_t 67 mpn_bdiv_qr_itch (mp_size_t nn, mp_size_t dn) 68 { 69 if (BELOW_THRESHOLD (dn, MU_BDIV_QR_THRESHOLD)) 70 return nn; 71 else 72 return mpn_mu_bdiv_qr_itch (nn, dn); 73 } 74