1 /* mpz_fdiv_qr_ui -- Division rounding the quotient towards -infinity. 2 The remainder gets the same sign as the denominator. 3 4 Copyright 1994, 1995, 1996, 1999, 2001, 2002, 2004 Free Software Foundation, 5 Inc. 6 7 This file is part of the GNU MP Library. 8 9 The GNU MP Library is free software; you can redistribute it and/or modify 10 it under the terms of the GNU Lesser General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or (at your 12 option) any later version. 13 14 The GNU MP Library is distributed in the hope that it will be useful, but 15 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 16 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 17 License for more details. 18 19 You should have received a copy of the GNU Lesser General Public License 20 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 21 22 #include "gmp.h" 23 #include "gmp-impl.h" 24 25 unsigned long int 26 mpz_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