1/* mpz_fdiv_qr_ui -- Division rounding the quotient towards -infinity. 2 The remainder gets the same sign as the denominator. 3 4Copyright 1994, 1995, 1996, 1999, 2001, 2002, 2004 Free Software Foundation, 5Inc. 6 7This file is part of the GNU MP Library. 8 9The GNU MP Library is free software; you can redistribute it and/or modify 10it under the terms of the GNU Lesser General Public License as published by 11the Free Software Foundation; either version 3 of the License, or (at your 12option) any later version. 13 14The GNU MP Library is distributed in the hope that it will be useful, but 15WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 16or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 17License for more details. 18 19You should have received a copy of the GNU Lesser General Public License 20along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 21 22#include "gmp.h" 23#include "gmp-impl.h" 24 25unsigned long int 26mpz_fdiv_qr_ui (mpz_ptr quot, mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor) 27{ 28 mp_size_t ns, nn, qn; 29 mp_ptr np, qp; 30 mp_limb_t rl; 31 32 if (divisor == 0) 33 DIVIDE_BY_ZERO; 34 35 ns = SIZ(dividend); 36 if (ns == 0) 37 { 38 SIZ(quot) = 0; 39 SIZ(rem) = 0; 40 return 0; 41 } 42 43 nn = ABS(ns); 44 MPZ_REALLOC (quot, nn); 45 qp = PTR(quot); 46 np = PTR(dividend); 47 48#if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */ 49 if (divisor > GMP_NUMB_MAX) 50 { 51 mp_limb_t dp[2]; 52 mp_ptr rp; 53 mp_size_t rn; 54 55 MPZ_REALLOC (rem, 2); 56 rp = PTR(rem); 57 58 if (nn == 1) /* tdiv_qr requirements; tested above for 0 */ 59 { 60 qp[0] = 0; 61 qn = 1; /* a white lie, fixed below */ 62 rl = np[0]; 63 rp[0] = rl; 64 } 65 else 66 { 67 dp[0] = divisor & GMP_NUMB_MASK; 68 dp[1] = divisor >> GMP_NUMB_BITS; 69 mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2); 70 rl = rp[0] + (rp[1] << GMP_NUMB_BITS); 71 qn = nn - 2 + 1; 72 } 73 74 if (rl != 0 && ns < 0) 75 { 76 mpn_incr_u (qp, (mp_limb_t) 1); 77 rl = divisor - rl; 78 rp[0] = rl & GMP_NUMB_MASK; 79 rp[1] = rl >> GMP_NUMB_BITS; 80 } 81 82 qn -= qp[qn - 1] == 0; qn -= qn != 0 && qp[qn - 1] == 0; 83 rn = 1 + (rl > GMP_NUMB_MAX); rn -= (rp[rn - 1] == 0); 84 SIZ(rem) = rn; 85 } 86 else 87#endif 88 { 89 rl = mpn_divrem_1 (qp, (mp_size_t) 0, np, nn, (mp_limb_t) divisor); 90 if (rl == 0) 91 SIZ(rem) = 0; 92 else 93 { 94 if (ns < 0) 95 { 96 mpn_incr_u (qp, (mp_limb_t) 1); 97 rl = divisor - rl; 98 } 99 100 PTR(rem)[0] = rl; 101 SIZ(rem) = rl != 0; 102 } 103 qn = nn - (qp[nn - 1] == 0); 104 } 105 106 SIZ(quot) = ns >= 0 ? qn : -qn; 107 return rl; 108} 109