1 /* mpn_bdiv_q_1, mpn_pi1_bdiv_q_1 -- schoolbook Hensel division by 1-limb 2 divisor, returning quotient only. 3 4 THE FUNCTIONS IN THIS FILE ARE FOR INTERNAL USE ONLY. THEY'RE ALMOST 5 CERTAIN TO BE SUBJECT TO INCOMPATIBLE CHANGES OR DISAPPEAR COMPLETELY IN 6 FUTURE GNU MP RELEASES. 7 8 Copyright 2000, 2001, 2002, 2003, 2005, 2009 Free Software Foundation, Inc. 9 10 This file is part of the GNU MP Library. 11 12 The GNU MP Library is free software; you can redistribute it and/or modify 13 it under the terms of the GNU Lesser General Public License as published by 14 the Free Software Foundation; either version 3 of the License, or (at your 15 option) any later version. 16 17 The GNU MP Library is distributed in the hope that it will be useful, but 18 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 19 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 20 License for more details. 21 22 You should have received a copy of the GNU Lesser General Public License 23 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 24 25 #include "gmp.h" 26 #include "gmp-impl.h" 27 #include "longlong.h" 28 29 mp_limb_t 30 mpn_pi1_bdiv_q_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t d, 31 mp_limb_t di, int shift) 32 { 33 mp_size_t i; 34 mp_limb_t c, h, l, u, u_next, dummy; 35 36 ASSERT (n >= 1); 37 ASSERT (d != 0); 38 ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n)); 39 ASSERT_MPN (up, n); 40 ASSERT_LIMB (d); 41 42 d <<= GMP_NAIL_BITS; 43 44 if (shift != 0) 45 { 46 c = 0; 47 48 u = up[0]; 49 rp--; 50 for (i = 1; i < n; i++) 51 { 52 u_next = up[i]; 53 u = ((u >> shift) | (u_next << (GMP_NUMB_BITS-shift))) & GMP_NUMB_MASK; 54 55 SUBC_LIMB (c, l, u, c); 56 57 l = (l * di) & GMP_NUMB_MASK; 58 rp[i] = l; 59 60 umul_ppmm (h, dummy, l, d); 61 c += h; 62 u = u_next; 63 } 64 65 u = u >> shift; 66 l = u - c; 67 l = (l * di) & GMP_NUMB_MASK; 68 rp[i] = l; 69 } 70 else 71 { 72 u = up[0]; 73 l = (u * di) & GMP_NUMB_MASK; 74 rp[0] = l; 75 c = 0; 76 77 for (i = 1; i < n; i++) 78 { 79 umul_ppmm (h, dummy, l, d); 80 c += h; 81 82 u = up[i]; 83 SUBC_LIMB (c, l, u, c); 84 85 l = (l * di) & GMP_NUMB_MASK; 86 rp[i] = l; 87 } 88 } 89 90 return c; 91 } 92 93 mp_limb_t 94 mpn_bdiv_q_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t d) 95 { 96 mp_limb_t di; 97 int shift; 98 99 ASSERT (n >= 1); 100 ASSERT (d != 0); 101 ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n)); 102 ASSERT_MPN (up, n); 103 ASSERT_LIMB (d); 104 105 if ((d & 1) == 0) 106 { 107 count_trailing_zeros (shift, d); 108 d >>= shift; 109 } 110 else 111 shift = 0; 112 113 binvert_limb (di, d); 114 return mpn_pi1_bdiv_q_1 (rp, up, n, d, di, shift); 115 } 116