| Austin Schuh | bb1338c | 2024-06-15 19:31:16 -0700 | [diff] [blame] | 1 | /* mpn_divrem -- Divide natural numbers, producing both remainder and |
| 2 | quotient. This is now just a middle layer calling mpn_tdiv_qr. |
| 3 | |
| 4 | Copyright 1993-1997, 1999-2002, 2005, 2016 Free Software Foundation, Inc. |
| 5 | |
| 6 | This file is part of the GNU MP Library. |
| 7 | |
| 8 | The GNU MP Library is free software; you can redistribute it and/or modify |
| 9 | it under the terms of either: |
| 10 | |
| 11 | * the GNU Lesser General Public License as published by the Free |
| 12 | Software Foundation; either version 3 of the License, or (at your |
| 13 | option) any later version. |
| 14 | |
| 15 | or |
| 16 | |
| 17 | * the GNU General Public License as published by the Free Software |
| 18 | Foundation; either version 2 of the License, or (at your option) any |
| 19 | later version. |
| 20 | |
| 21 | or both in parallel, as here. |
| 22 | |
| 23 | The GNU MP Library is distributed in the hope that it will be useful, but |
| 24 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 25 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 26 | for more details. |
| 27 | |
| 28 | You should have received copies of the GNU General Public License and the |
| 29 | GNU Lesser General Public License along with the GNU MP Library. If not, |
| 30 | see https://www.gnu.org/licenses/. */ |
| 31 | |
| 32 | #include "gmp-impl.h" |
| 33 | #include "longlong.h" |
| 34 | |
| 35 | mp_limb_t |
| 36 | mpn_divrem (mp_ptr qp, mp_size_t qxn, |
| 37 | mp_ptr np, mp_size_t nn, |
| 38 | mp_srcptr dp, mp_size_t dn) |
| 39 | { |
| 40 | ASSERT (qxn >= 0); |
| 41 | ASSERT (nn >= dn); |
| 42 | ASSERT (dn >= 1); |
| 43 | ASSERT (dp[dn-1] & GMP_NUMB_HIGHBIT); |
| 44 | ASSERT (! MPN_OVERLAP_P (np, nn, dp, dn)); |
| 45 | ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, np, nn) || qp==np+dn+qxn); |
| 46 | ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, dp, dn)); |
| 47 | ASSERT_MPN (np, nn); |
| 48 | ASSERT_MPN (dp, dn); |
| 49 | |
| 50 | if (dn == 1) |
| 51 | { |
| 52 | mp_limb_t ret; |
| 53 | mp_ptr q2p; |
| 54 | mp_size_t qn; |
| 55 | TMP_DECL; |
| 56 | |
| 57 | TMP_MARK; |
| 58 | q2p = TMP_ALLOC_LIMBS (nn + qxn); |
| 59 | |
| 60 | np[0] = mpn_divrem_1 (q2p, qxn, np, nn, dp[0]); |
| 61 | qn = nn + qxn - 1; |
| 62 | MPN_COPY (qp, q2p, qn); |
| 63 | ret = q2p[qn]; |
| 64 | |
| 65 | TMP_FREE; |
| 66 | return ret; |
| 67 | } |
| 68 | else if (dn == 2) |
| 69 | { |
| 70 | return mpn_divrem_2 (qp, qxn, np, nn, dp); |
| 71 | } |
| 72 | else |
| 73 | { |
| 74 | mp_ptr q2p; |
| 75 | mp_limb_t qhl; |
| 76 | mp_size_t qn; |
| 77 | TMP_DECL; |
| 78 | |
| 79 | TMP_MARK; |
| 80 | if (UNLIKELY (qxn != 0)) |
| 81 | { |
| 82 | mp_ptr n2p; |
| 83 | TMP_ALLOC_LIMBS_2 (n2p, nn + qxn, |
| 84 | q2p, nn - dn + qxn + 1); |
| 85 | MPN_ZERO (n2p, qxn); |
| 86 | MPN_COPY (n2p + qxn, np, nn); |
| 87 | mpn_tdiv_qr (q2p, np, 0L, n2p, nn + qxn, dp, dn); |
| 88 | qn = nn - dn + qxn; |
| 89 | MPN_COPY (qp, q2p, qn); |
| 90 | qhl = q2p[qn]; |
| 91 | } |
| 92 | else |
| 93 | { |
| 94 | q2p = TMP_ALLOC_LIMBS (nn - dn + 1); |
| 95 | mpn_tdiv_qr (q2p, np, 0L, np, nn, dp, dn); |
| 96 | qn = nn - dn; |
| 97 | MPN_COPY (qp, q2p, qn); |
| 98 | qhl = q2p[qn]; |
| 99 | } |
| 100 | TMP_FREE; |
| 101 | return qhl; |
| 102 | } |
| 103 | } |