cdiv_r_ui.c revision 1.1.1.3
1/* mpz_cdiv_r_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 6Copyright 1994-1996, 2001, 2002, 2004, 2005, 2012 Free Software Foundation, 7Inc. 8 9This file is part of the GNU MP Library. 10 11The GNU MP Library is free software; you can redistribute it and/or modify 12it 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 18or 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 24or both in parallel, as here. 25 26The GNU MP Library is distributed in the hope that it will be useful, but 27WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 28or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 29for more details. 30 31You should have received copies of the GNU General Public License and the 32GNU Lesser General Public License along with the GNU MP Library. If not, 33see https://www.gnu.org/licenses/. */ 34 35#include "gmp.h" 36#include "gmp-impl.h" 37 38unsigned long int 39mpz_cdiv_r_ui (mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor) 40{ 41 mp_size_t ns, nn; 42 mp_ptr np; 43 mp_limb_t rl; 44 45 if (UNLIKELY (divisor == 0)) 46 DIVIDE_BY_ZERO; 47 48 ns = SIZ(dividend); 49 if (ns == 0) 50 { 51 SIZ(rem) = 0; 52 return 0; 53 } 54 55 nn = ABS(ns); 56 np = PTR(dividend); 57#if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */ 58 if (divisor > GMP_NUMB_MAX) 59 { 60 mp_limb_t dp[2]; 61 mp_ptr rp, qp; 62 mp_size_t rn; 63 TMP_DECL; 64 65 rp = MPZ_REALLOC (rem, 2); 66 67 if (nn == 1) /* tdiv_qr requirements; tested above for 0 */ 68 { 69 rl = np[0]; 70 rp[0] = rl; 71 } 72 else 73 { 74 TMP_MARK; 75 dp[0] = divisor & GMP_NUMB_MASK; 76 dp[1] = divisor >> GMP_NUMB_BITS; 77 qp = TMP_ALLOC_LIMBS (nn - 2 + 1); 78 mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2); 79 TMP_FREE; 80 rl = rp[0] + (rp[1] << GMP_NUMB_BITS); 81 } 82 83 if (rl != 0 && ns >= 0) 84 { 85 rl = divisor - rl; 86 rp[0] = rl & GMP_NUMB_MASK; 87 rp[1] = rl >> GMP_NUMB_BITS; 88 } 89 90 rn = 1 + (rl > GMP_NUMB_MAX); rn -= (rp[rn - 1] == 0); 91 SIZ(rem) = -rn; 92 } 93 else 94#endif 95 { 96 rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor); 97 if (rl == 0) 98 SIZ(rem) = 0; 99 else 100 { 101 if (ns >= 0) 102 rl = divisor - rl; 103 104 PTR(rem)[0] = rl; 105 SIZ(rem) = -1; 106 } 107 } 108 109 return rl; 110} 111