| Austin Schuh | bb1338c | 2024-06-15 19:31:16 -0700 | [diff] [blame] | 1 | /* mpz_cdiv_ui -- Division rounding the quotient towards +infinity. The |
| 2 | remainder gets the opposite sign as the denominator. In order to make it |
| 3 | always fit into the return type, the negative of the true remainder is |
| 4 | returned. |
| 5 | |
| 6 | Copyright 1994-1996, 2001, 2002, 2004, 2005, 2012 Free Software Foundation, |
| 7 | Inc. |
| 8 | |
| 9 | This file is part of the GNU MP Library. |
| 10 | |
| 11 | The GNU MP Library is free software; you can redistribute it and/or modify |
| 12 | it under the terms of either: |
| 13 | |
| 14 | * the GNU Lesser General Public License as published by the Free |
| 15 | Software Foundation; either version 3 of the License, or (at your |
| 16 | option) any later version. |
| 17 | |
| 18 | or |
| 19 | |
| 20 | * the GNU General Public License as published by the Free Software |
| 21 | Foundation; either version 2 of the License, or (at your option) any |
| 22 | later version. |
| 23 | |
| 24 | or both in parallel, as here. |
| 25 | |
| 26 | The GNU MP Library is distributed in the hope that it will be useful, but |
| 27 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 28 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 29 | for more details. |
| 30 | |
| 31 | You should have received copies of the GNU General Public License and the |
| 32 | GNU Lesser General Public License along with the GNU MP Library. If not, |
| 33 | see https://www.gnu.org/licenses/. */ |
| 34 | |
| 35 | #include "gmp-impl.h" |
| 36 | |
| 37 | unsigned long int |
| 38 | mpz_cdiv_ui (mpz_srcptr dividend, unsigned long int divisor) |
| 39 | { |
| 40 | mp_size_t ns, nn; |
| 41 | mp_ptr np; |
| 42 | mp_limb_t rl; |
| 43 | |
| 44 | if (UNLIKELY (divisor == 0)) |
| 45 | DIVIDE_BY_ZERO; |
| 46 | |
| 47 | ns = SIZ(dividend); |
| 48 | if (ns == 0) |
| 49 | { |
| 50 | return 0; |
| 51 | } |
| 52 | |
| 53 | nn = ABS(ns); |
| 54 | np = PTR(dividend); |
| 55 | #if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */ |
| 56 | if (divisor > GMP_NUMB_MAX) |
| 57 | { |
| 58 | mp_limb_t dp[2], rp[2]; |
| 59 | mp_ptr qp; |
| 60 | mp_size_t rn; |
| 61 | TMP_DECL; |
| 62 | |
| 63 | if (nn == 1) /* tdiv_qr requirements; tested above for 0 */ |
| 64 | { |
| 65 | rl = np[0]; |
| 66 | rp[0] = rl; |
| 67 | } |
| 68 | else |
| 69 | { |
| 70 | TMP_MARK; |
| 71 | dp[0] = divisor & GMP_NUMB_MASK; |
| 72 | dp[1] = divisor >> GMP_NUMB_BITS; |
| 73 | qp = TMP_ALLOC_LIMBS (nn - 2 + 1); |
| 74 | mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2); |
| 75 | TMP_FREE; |
| 76 | rl = rp[0] + (rp[1] << GMP_NUMB_BITS); |
| 77 | } |
| 78 | |
| 79 | if (rl != 0 && ns >= 0) |
| 80 | { |
| 81 | rl = divisor - rl; |
| 82 | rp[0] = rl & GMP_NUMB_MASK; |
| 83 | rp[1] = rl >> GMP_NUMB_BITS; |
| 84 | } |
| 85 | |
| 86 | rn = 1 + (rl > GMP_NUMB_MAX); rn -= (rp[rn - 1] == 0); |
| 87 | } |
| 88 | else |
| 89 | #endif |
| 90 | { |
| 91 | rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor); |
| 92 | if (rl == 0) |
| 93 | ; |
| 94 | else |
| 95 | { |
| 96 | if (ns >= 0) |
| 97 | rl = divisor - rl; |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | return rl; |
| 102 | } |